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asclépiade à fleurs vertes, green antelopehorn milkweed, green comet milkweed, green milkweed

milkweed

Habit Herbs. Herbs, subshrubs, or shrubs, rhizomatous or not; latex milky (clear).
Stems

solitary, erect to ascending, unbranched (rarely), (10–)20–125 cm, puberulent with curved trichomes, not glaucous, rhizomes absent.

not twining, unarmed, pubescent or glabrous.

Leaves

opposite to subopposite, sessile or petiolate, with 1 or 2 stipular colleters on each side of petiole and also in axil;

petiole 0–5 mm, puberulent with curved trichomes;

blade linear to broadly oval or nearly orbiculate, 2–13 × 0.8–6 cm, chartaceous, base cuneate to rounded, margins entire or crisped, apex acute or obtuse to truncate or emarginate, mucronate, venation brochidodromous, surfaces sparsely pilosulous to glabrate, margins ciliate, laminar colleters absent.

persistent (caducous), opposite, subopposite, alternate, or whorled, petiolate or sessile;

stipular colleters interpetiolar (absent);

laminar colleters present or absent.

Inflorescences

extra-axillary at upper nodes, sometimes branched at peduncle apex, sessile or pedunculate, 22–60-flowered;

peduncle 0–4 cm, puberulent with curved trichomes to pilosulous, with 1 caducous bract at the base of each pedicel.

extra-axillary or terminal, umbelliform, pedunculate or sessile.

Pedicels

7–13 mm, pilosulous.

Flowers

erect to pendent;

calyx lobes narrowly lanceolate, 2–3 mm, apex acute, pilosulous;

corolla green to yellowish green, sometimes tinged red, lobes reflexed, oblong, 5–7 mm, apex acute, inconspicuously pilosulous at apex abaxially, glabrous adaxially;

gynostegium sessile;

fused anthers green, cylindric, 3–4 mm, wings triangular, widest at middle, closed, apical appendages ovate, marginally inflexed, apically deflexed;

corona segments green to cream, sometimes tinged red, sessile, laminar, margins incurved, appressed to column, 3–4 mm, greatly exceeded by style apex, apex obtuse, glabrous, internal appendage absent or obscure, glabrous;

style apex shallowly depressed, green.

calycine colleters present or absent;

corolla green, white, cream, pink, red, maroon, purple, orange, or yellow, rotate with lobes usually reflexed to spreading (campanulate, tubular), aestivation valvate;

coralline corona absent;

androecium and gynoecium united into a gynostegium adnate to corolla tube;

gynostegial corona of 1 whorl of 5 thick, cupulate, laminar, or clavate segments, often bearing an adaxial falcate, subulate, acicular, lingulate, or crestlike appendage;

anthers adnate to style, locules 2;

pollen in each theca massed into a rigid, vertically oriented pollinium, pollinia lachrimiform, joined from adjacent anthers by translators to a common corpusculum and together forming a pollinarium.

Fruits

follicles, usually solitary, erect (spreading) on upcurved or straight pedicels or pendulous, green to brown, fusiform, lance-ovoid, ovoid, or ellipsoid, smooth (ornamented), pubescent or glabrous.

Seeds

ovate, 7–8 × 4–5 mm, margin winged, faces minutely rugulose;

coma 2.5–3 cm.

ovate or lanceolate to nearly orbiculate, flattened (naviculate in A. albicans, A. linaria; flat to somewhat naviculate in A. subulata), usually winged, not beaked, comose (coma absent in A. perennis), not arillate;

comas white.

Follicles

erect on upcurved pedicels, fusiform to lance-ovoid, 6–10 × 1.5–2 cm, apex acuminate to attenuate, smooth, pilosulous.

x

= 11.

2n

= 22.

Asclepias viridiflora

Asclepias

Phenology Flowering Apr–Sep(–Oct); fruiting Jun–Nov.
Habitat Slopes, ridges, bluffs, flats, canyons, arroyos, glades, fields, meadows, pastures, sandhills, dunes, pond edges, streamsides, playas, sandstone, limestone, gypsum, ser­pentine, dolomite, alluvium, silty, sandy, clay, rocky, and calcareous soils, prairies, desert grasslands, oak scrub, oak, oak-juniper, oak-hickory, pine-oak, and pine woodlands, forest openings and edges.
Elevation 0–2300 m. (0–7500 ft.)
Distribution
from FNA
AL; AR; AZ; CO; CT; DC; DE; FL; GA; IA; IL; IN; KS; KY; LA; MD; MI; MN; MO; MS; MT; NC; ND; NE; NJ; NM; NY; OH; OK; PA; SC; SD; TN; TX; VA; WI; WV; WY; AB; MB; ON; SK; Mexico (Coahuila)
[WildflowerSearch map]
[BONAP county map]
from USDA
North America; Mexico; Central America; South America; West Indies; Africa [Introduced in Europe and pan-tropical areas]
[BONAP county map]
Discussion

Asclepias viridiflora is one of the milkweeds with spherical, greenish umbels and inconspicuous coronas (see also A. engelmanniana, A. hirtella, A. lanuginosa, A. longifolia, A. rusbyi, A. stenophylla). Prior to close examination, the tight green balls of open flowers appear to be merely in bud. The diversity in leaf morphology among individuals (linear to orbiculate) is remarkable, but has no taxonomic significance—the full range of variation may be found within single populations. This is the most widespread milkweed within the flora area, ranging across most of the United States (absent only from the westernmost states and most of New England) and southern Canada. It is nowhere abundant, but may be regularly encountered in suitable, thin-soiled prairie habitats, especially in the Great Plains. It is rare and considered to be of conservation concern on the margins of its range, in Alberta (Cypress, Forty Mile, and Warner counties), Arizona (Coconino, Gila, and Yavapai counties), Connecticut (New Haven County), Florida (Gadsden and Jackson counties), and New York (Columbia, Nassau, Richmond, and Suffolk counties).

(Discussion copyrighted by Flora of North America; reprinted with permission.)

Species ca. 400 (77 in the flora).

In its broad sense, Asclepias is the largest genus of Apocynaceae. Attempts have been made to segregate the African species into some 20 genera, but these attempts have left a residuum of African species in Asclepias that are more closely related to segregate African genera than to the type-bearing American species (D. J. Goyder et al. 2007; Goyder 2009; D. Chuba et al. 2017). Hence, the broader circumscription is adopted here, although the American species as a whole (ca. 130 species) are monophyletic, and circumscription does not affect the nomenclature of the species in the flora.

Species of Asclepias are ecologically diverse, with habitats ranging from marshes and swamps to some of the driest regions in the North American and African deserts. They occur from sea level to over 3000 m elevation. However, the genus has diversified most dramatically in grasslands, savannas, woodlands, and forests, in seasonally dry, temperate and subtropical climates, and it is in these ecoregions that milkweeds are most conspicuous. All species are perennial, and the great majority are seasonally dormant herbs. Most species occur in environments subject to one or more of the following disturbances: extended freezing, drought, fire, or mammalian grazing. Nonetheless, the species are diverse in growth form and phenology—habit ranges from diminutive herbs less than 5 cm tall to herbs and shrubs exceeding 2 m in height, and flowering ranges from constrained two-week periods to year-round.

Two aspects of the ecology of Asclepias have received extensive study—reproductive and defensive strategies. As with Asclepiadoideae as a whole, Asclepias species have elaborate and precise insect pollination involving pollinia and coronas that mediate interactions with pollinators. Asclepias has been the most intensively studied genus in the subfamily with regard to the diversity of the pollinating fauna and forces that have shaped the evolution of floral traits. Whereas pollinator interactions in Asclepiadoideae genera vary widely from highly specialized to highly generalized (J. Ollerton et al. 2019), those species of Asclepias that have been studied quantitatively are moderately to highly generalized, including such species as A. tuberosa, commonly known as butterflyweed (M. Fishbein and D. L. Venable 1996). However, such studies are limited to fewer than a dozen species, and the existence of more specialized pollination seems likely for more rare and poorly known species. Species of Asclepias have also served as a model system for testing the hypothesis that the characteristically low fruit set in the genus is a consequence of sexual selection to increase flower number through competition among plants as pollen donors (M. F. Willson and B. J. Rathcke 1974; S. B. Broyles and R. Wyatt 1990; Fishbein and Venable 1996b).

The chemical ecology of Asclepias also has been widely studied because a class of secondary metabolites, cardiac glycosides (cardenolides), which is found in many Apocynaceae species, is sequestered by several specialist Asclepias-feeding insect herbivores and used as their own defense compounds (A. A. Agrawal et al. 2012). The interaction between Asclepias species and the monarch butterfly, Danaus plexippus, has been most intensively studied (L. P. Brower et al. 1967). Subsequently, the diversity of defensive traits of milkweeds (cardenolides, latex, trichomes, waxes, etc.) has been analyzed in an evolutionary context, considering also the functions of some of these traits as adaptations for drought resistance (Agrawal et al. 2009; M. Fishbein et al. 2018).

Species of Asclepias have been investigated for development of commercial products. Production of natural rubber from latex has not proved economical, even during the time of World War II shortages. There have been repeated efforts to develop an industry around harvesting seed comas as floss for stuffing and insulation. Mechanization has proved challenging, but a small industry is developing, based largely on A. syriaca because of its rapid growth and high seed production. Asclepias species have been used as a source of medicine by most Native American tribes for diverse ailments. One of the common names of A. tuberosa is pleurisy root, and the tuberous roots of this species have been included in herbal remedies for coughing and congestion. This seems to be the only commercialization of American milkweeds for medicinal purposes, and no clinical trials have taken place in North America involving milkweed-derived compounds. Despite toxicity, there is a tradition in native and immigrant American communities, particularly in the Appalachian region, of using young shoots of A. syriaca as a vegetable, following boiling with two changes of water.

Species such as Asclepias curassavica, A. incarnata, and A. tuberosa are widely cultivated, and horticultural varietals are available. Recently, the popularity of diverse species of Asclepias as components of home and commercial gardens, as well as synthetic prairies, is skyrocketing, fueled in part by interest in growing food plants for monarch butterflies, or more generally as a nectar source for the conservation of pollinator communities. Surprisingly, A. subulata, found naturally on arid, sandy substrates, grows rapidly in standard potting media and is becoming ubiquitous in horticultural settings in Arizona. At least 25 species are available from nurseries across the flora area.

In the key and descriptions the following conventions are used. Leaf measurements pertain to midstem leaves, usually at the node below the first inflorescence. The lowest leaves and those in the flowering portion of the plant are commonly much smaller than midstem leaves and are less useful for identification. Vestiture of stems and leaves (unless otherwise specified) is described for mature structures below the inflorescences; many species possess trichomes on stems and leaves early in development that are lost with maturity but continue to be produced on new structures in the flowering portion of the plant. The gynostegial column refers to the cylindrical structure formed by the united filaments; its length is measured from its attachment to the corolla to the base of the anthers. The corona of Asclepias consists largely of five discrete segments that are usually cavitate and are often referred to as hoods. In some species, these segments are strongly compressed dorsally and the cavity is greatly reduced. In others, the margins of the segments are folded in, obscuring the cavity and creating a club-shaped form. The majority of species also have an adaxial appendage of each segment, often referred to as a horn, which arises from within the cavity and is often exserted. In some species, the appendage is merely a crest within the cavity, and it may be altogether absent. The diversity of corona forms is difficult to describe, but these features are highly useful for identification. They are ideally observed in fresh material, and photographs are invaluable.

A revised infrageneric classification of Asclepias is needed. The species in this treatment are arranged according to phylogenetic relationships obtained from analyses of plastid genomes (M. Fishbein et al. 2018) and a set of 768 nuclear loci (J. Boutte et al. 2019). These correspond largely to the major clades presented by Fishbein et al. (2011). Species 1–3 are early-diverging lineages, species 4–6 belong to the Sonoran Desert clade, species 7–16 belong to the Incarnatae clade, species 17–22 are not placed in a major clade, species 23–27 belong to the Mexican highland clade, and species 28–77 belong to the temperate North American clade. Within the temperate North American clade, several subclades are strongly supported: species 37 in the waxy clade, species 39–42 in the Podostemma clade, species 51–56 in the Colorado Plateau clade, species 57–60 in the dwarf clade, and species 61–77 in the eastern temperate clade.

(Discussion copyrighted by Flora of North America; reprinted with permission.)

Key
1. Leaves alternate (sometimes a few subopposite).
→ 2
2. Leaf blades filiform or needlelike to narrowly linear, 0.05–0.3 cm wide.
→ 3
3. Stems 30–160 cm.
→ 4
4. Stems woody, few–numerous; leaf blades needlelike, less than 4 cm; corona segments with rod-shaped, slightly exserted appendages.
A. linaria
4. Stems herbaceous, 1–3 (rarely more); leaf blades not needlelike, greater than 4 cm; corona segment appendages absent or at most a low crest.
→ 5
5. Stems glabrous; anthers 2–3 mm.
→ 6
6. Gynostegial column 0.5–1.5 mm; fused anthers barrel-shaped, anther wings evenly crescent-shaped and separate throughout, apical anther appendages narrowly pandurate, conduplicate, not obscuring corpuscula.
A. engelmanniana
6. Gynostegial column 0–0.5 mm; fused anthers obconic, anther wings connivent, except at the wider base, apical anther appendages deltoid, obscuring corpuscula.
A. rusbyi
5. Stems puberulent with curved trichomes; anthers 1–2 mm.
→ 7
7. Leaf blades conduplicate; corolla lobe apices minutely puberulent with curved trichomes abaxially; fused anthers obconic, 1.5–2 mm, anther wings narrowly crescent-shaped; corona segments 3–3.5 mm, appendage an internal crest, apex appearing 3-toothed; follicles erect on straight pedicels.
A. stenophylla
7. Leaf blades flat; corolla lobes glabrous; fused anthers cylindric, 1–1.5 mm, anther wings trapezoidal to triangular; corona segments 1.5–2.5 mm, appendage absent or obscure, apex not appearing toothed; follicles erect on upcurved pedicels.
→ 8
8. Corona segments 1.5–2 mm, not exceeding point of anther wings; pedicels and calyces hirtellous; follicles 1–2 cm wide; flowers 34–112 per umbel.
A. hirtella
8. Corona segments 2–2.5 mm, exceeding point of anther wings; pedicels and calyces puberulent with curved trichomes; follicles 0.7–1.2 cm wide; flowers 13–28(–36) per umbel.
A. longifolia
3. Stems 5–30 cm.
→ 9
9. Corona segments strongly dorsally compressed and laminar or chute-shaped, appendage absent or merely a low crest, wholly included.
→ 10
10. Leaf blades conduplicate; corolla lobe apices puberulent with minute, curved trichomes abaxially; fused anthers obconic, 1.5–2 mm, anther wings narrowly crescent-shaped; corona segments 3–3.5 mm, appendage an internal crest, apex appearing 3-toothed; follicles erect on straight pedicels.
A. stenophylla
10. Leaf blades flat; corolla lobes glabrous; fused anthers cylindric, 1–1.5 mm, anther wings trapezoidal to triangular; corona segments 2–2.5 mm, appendage absent or obscure, apex not appearing toothed; follicles erect on upcurved pedicels.
A. longifolia
9. Corona segments conduplicate, cupulate, or tubular, appendage lingulate, falcate or acicular, barely to well exserted.
→ 11
11. Corolla lobes 4.5–6 mm; corona segments 3.5–4.5 mm; follicles 1.5–2 cm wide, rugose.
A. involucrata
11. Corolla lobes 2.5–5 mm; corona segments 1–3.5 mm; follicles 0.5–1.5 cm wide, smooth.
→ 12
12. Corollas red-violet; corona segment appendages lingulate, barely exserted; follicles pendulous on spreading to declined pedicels or erect on upcurved pedicels.
→ 13
13. Stems erect to ascending; leaves sessile, blades strigose to glabrate; corona segments white; follicles pendulous on spreading to declined pedicels.
A. cutleri
13. Stems decumbent; leaves petiolate, petioles 1–5 mm, blades puber­ulent with curved trichomes on midvein; corona segments red-violet at base, white to orange at apex, follicles erect on upcurved pedicels.
A. uncialis
12. Corollas pink, cream, green, or tan; corona segment appendages falcate or acicular, well exserted; follicles erect on straight pedicels.
→ 14
14. Leaf blades needlelike to narrowly linear, 0.05–0.1 cm wide; anthers 1–1.5 mm; corona segment appendages acicular, arching towards style apex, follicles 2.5–9.5 cm.
A. pumila
14. Leaf blades narrowly linear, 0.1–0.4 cm wide; anthers 1.5–3 mm; corona segment appendages falcate, sharply inflexed over style apex; follicles 7.5–12.5 cm.
A. michauxii
2. Leaf blades linear, elliptic, oblong, oval, lanceolate, ovate, oblanceolate, obovate, or falcate, 0.3–9 cm wide.
→ 15
15. Corolla lobes ascending and exceeding corona segments, 7–15 mm; corona segments clavate-tubular, deflexed at base, ascending to incurved at apex, margins connivent.
→ 16
16. Leaf blade bases cuneate, apices acute to attenuate; peduncles not branched; corolla lobes 7–10 mm, puberulent abaxially at apex with curved trichomes; corona segments 4.5–7 mm, margins and appendage papillose.
A. asperula
16. Leaf blade bases rounded to subcordate, apices obtuse to rounded; peduncles usually branched; corolla lobes (9–)12–15 mm, glabrous; corona segments 3–5 mm, margins and appendage hirtellous.
A. viridis
15. Corolla lobes reflexed, sometimes with spreading tips, not overtopping corona segments, 3–9 mm; corona segments cupulate, tubular, conduplicate, chute-shaped, or laminar, margins separate.
→ 17
17. Corona segments strongly dorsally compressed and laminar or chute-shaped, appendage absent or merely a low crest.
→ 18
18. Leaf blades conduplicate; corolla lobe apices puberulent abaxially with minute, curved trichomes; fused anthers obconic, anther wings narrowly crescent-shaped; corona segment appendages crestlike, segment apices appearing 3-toothed; follicles erect on straight pedicels.
A. stenophylla
18. Leaf blades flat; corolla lobes glabrous; fused anthers cylindric, anther wings trapezoidal to triangular; corona segment appendages absent, segment apices untoothed; follicles erect on upcurved pedicels.
→ 19
19. Stems 7–20 cm, hirtellous to pilose; leaf blades hirtellous; fused anthers 1.5–2 mm; follicles hirtellous to pilose; seeds 6–7 × 4–5 mm.
A. lanuginosa
19. Stems 25–125 cm, puberulent with curved trichomes; leaf blades puberulent with curved trichomes or scabridulous; fused anthers 1–1.5 mm; follicles puberulent with curved trichomes to pilosulous; seeds 10–12 × 7–8 mm.
→ 20
20. Flowers 34–112 per umbel; pedicels and calyces hirtellous; corona segments 1.5–2 mm, not exceeding point of anther wings; follicles 1–2 cm wide.
A. hirtella
20. Flowers 13–28(–36) per umbel; pedicels and calyces puberulent with curved trichomes; corona segments 2–2.5 mm, exceeding point of anther wings; follicles 0.7–1.2 cm wide.
A. longifolia
17. Corona segments cupulate, tubular, or conduplicate, at most slightly flattened dorsally, appendage lingulate, falcate, subulate, or conical, barely to well exserted from cavity.
→ 21
21. Stems 15–100 cm; corolla lobes 4–9 mm.
→ 22
22. Corona segments 5–7 mm.
→ 23
23. Stems, leaves, and peduncles puberulent with curved trichomes, pilosulous, tomentulose, or glabrate; corollas pink, red, or green; coronas cream, segments with reddish or purplish dorsal stripes; anthers brown; follicles pilosulous; seeds 6–7 mm.
A. hallii
23. Stems, leaves, and peduncles hirsute; corollas and coronas red, orange, or yel­low; anthers yellow to yellowish green; follicles hirsute; seeds 8–9 mm.
A. tuberosa
22. Corona segments 2.5–3.5 mm.
→ 24
24. Pedicels 9–12 mm; corolla lobes 4–5 mm; corona segments cupulate, apex obtuse; fruiting pedicels straight, follicles 0.5–0.7 cm wide; se United States.
A. michauxii
24. Pedicels 15–50 mm; corolla lobes 6–9 mm; corona segments conduplicate, apex truncate; fruiting pedicels pendulous or upcurved, follicles 1.2–3 cm wide; California or Utah.
→ 25
25. Leaf blades 2–8 cm wide, tomentose to densely puberulent with curved trichomes; anthers brown, 2.5–3 mm; follicles erect on upcurved pedicels, 5–10 cm; seeds 7–9 × 4–6 mm.
A. eriocarpa
25. Leaf blades 0.5–2 cm wide, glabrous except for midvein; anthers green to yellowish green, 1.5–2 mm; follicles pendulous, 3.5–5.5 cm; seeds 12–13 × 8–9 mm.
A. labriformis
21. Stems 5–15 cm; corolla lobes 3–6 mm.
→ 26
26. Corollas green, sometimes tinged red or pink; corona segment appendages well exserted, sharply inflexed towards or over style apex; follicles rugose.
→ 27
27. Leaf blades 0.2–0.8 cm wide; anthers 1.5–2 mm; corona segments cream, usually with a pink or red dorsal stripe, conduplicate, 3.5–4.5 mm; seeds 7–8 × 5–6 mm.
A. involucrata
27. Leaf blades 0.5–2 cm wide; anthers 1–1.5 mm; corona segments yellow to ochroleucous, tubular, 2–3 mm; seeds 8–12 × 6–8 mm.
A. macrosperma
26. Corollas red-violet; corona segment appendages equaling or barely exserted from segment; follicles smooth.
→ 28
28. Corona segment appendages falcate, not or barely exserted; Colorado Plateau, ne Arizona, nw New Mexico, Utah.
→ 29
29. Leaf blades persistently pilosulous, more densely so on veins; pedicels and calyces densely pilosulous to tomentulose; corona segment appendages barely exserted; Utah, n of Colorado River and w of Green River, from San Rafael Reef to Waterpocket Fold.
A. ruthiae
29. Leaf blades sparsely pilosulous to glabrate, persistently hairy on veins; pedicels and calyces pilosulous; corona segment appendages included; Arizona, New Mexico, just entering Utah in Monument Valley.
A. sanjuanensis
28. Corona segment appendages lingulate or conical, barely exserted; Arizona, Colorado, Nevada, New Mexico, Oklahoma, Texas, not on the Colorado Plateau.
→ 30
30. Leaf blades lanceolate to ovate, 0.6–3 cm wide, strigulose or puberulent on midvein to glabrate; flowers 2–25 per umbel; anthers 1.5–2 mm; corona appendages conical; Nevada.
A. eastwoodiana
30. Leaf blades linear to lanceolate, 0.2–1 cm wide, puberulent with curved trichomes on midvein; flowers 3–7 per umbel; anthers 1–1.5 mm; corona appendages lingulate; Arizona, Colorado, New Mexico, Oklahoma, Texas.
A. uncialis
1. Leaves opposite, subopposite, or whorled (rarely alternate in A. eriocarpa).
→ 31
31. One or more nodes with leaves whorled or (in A. quadrifolia) apparently whorled because of a reduced internode.
→ 32
32. Shrubs, 50–400 cm; leaves ephemeral; stems often leafless or nearly so, glaucous; follicles spreading to pendulous; Sonoran Desert and se Mohave Desert, sw Arizona, se California, s Nevada.
→ 33
33. Stems 5–40 (usually 1–few), 140–400 cm; pedicels 8–16 mm; corolla lobes 4.5–6 mm; corona segments 2–3 mm, conduplicate, not exceeding style apex.
A. albicans
33. Stems 3–100 (usually few–numerous), 50–175 cm; pedicels 11–21 mm; corolla lobes 7–12 mm; corona segments 7–9 mm, tubular, greatly exceeding style apex.
A. subulata
32. Herbs; stems 20–150 cm; leaves persistent; stems leafy, not glaucous; follicles erect on straight or upcurved pedicels; widespread, approaching but not entering the Sonoran Desert.
→ 34
34. At least some leaves on main stem alternate or opposite, blades elliptic or lanceolate to ovate, 1–8 cm wide; corona lobes 2.5–4 mm.
→ 35
35. Plants 1–10-stemmed; whorled leaves, when present, at upper nodes, leaf blades tomentose to densely puberulent with curved trichomes; pedicels and calyces densely tomentose; corolla lobes 7–9 mm; follicles erect on upcurved pedicels, lance-ovoid, 1.5–3 cm wide; California.
A. eriocarpa
35. Plants single-stemmed; whorled leaves, when present, at a single, mid-stem node; leaf blades inconspicuously puberulent only on veins; pedicels puberlent on 1 side; calyces glabrous; corolla lobes 4–5 mm; follicles erect on straight pedicels, narrowly fusiform, 0.4–1 cm wide; e North America.
A. quadrifolia
34. All leaves whorled (rarely opposite on vegetative branches), blades linear to linear-lanceolate or narrowly elliptic, 0.1–1.8 cm wide; corona lobes 1.5–2 mm.
→ 36
36. Leaf blades 0.2–1.8 cm wide; pedicels 9–14 mm; corollas pink (rarely green with pink tinge); California, Idaho, Nevada, Oregon, Washington.
A. fascicularis
36. Leaf blades 0.1–0.4 cm wide; pedicels 5–12 mm; corollas green to cream, sometimes tinged pink or tan; widespread, s or e of Idaho, Nevada.
→ 37
37. Stems 1–8, vegetative branches often present in 1+ leaf axils; leaf blades 0.1–0.4 cm wide, glabrous; anthers 1.5–2 mm; corona segment margins entire; w United States, including w Kansas, w Oklahoma, w Texas.
A. subverticillata
37. Stems solitary (rarely 2–3), vegetative branches absent; leaf blades 0.1–0.2 cm wide, puberulent with curved trichomes adaxially, especially on midvein to glabrate; anthers 1.2–1.5 mm; corona segment margins shallowly lobed to sharply toothed; e North America, e of Colorado, Idaho, New Mexico.
A. verticillata
31. Leaves opposite or subopposite, not whorled.
→ 38
38. Leaf blades filiform to narrowly linear, 0.05–0.3 cm wide.
→ 39
39. Shrubs, 50–400 cm; leaves ephemeral; stems often leafless or nearly so, glaucous; follicles spreading to pendulous; Sonoran Desert and se Mohave Desert, sw Arizona, se California, s Nevada.
→ 40
40. Stems 5–40 (usually 1–few), 140–400 cm; pedicels 8–16 mm; corolla lobes 4.5–6 mm; corona segments 2–3 mm, conduplicate, not exceeding style apex.
A. albicans
40. Stems 3–100 (usually few–numerous), 50–175 cm; pedicels 11–21 mm; corolla lobes 7–12 mm; corona segments 7–9 mm, tubular, greatly exceeding style apex.
A. subulata
39. Subshrubs or herbs; stems 4–125 cm; leaves persistent; stems leafy, not glaucous; follicles erect on straight or upcurved pedicels; approaching but not entering the Sonoran Desert.
→ 41
41. Stems prostrate to decumbent.
→ 42
42. Stems 4–18 cm; petioles 1–5 mm; umbels sessile; follicles ovoid, 3–5.5 cm; Arizona, Colorado, Kansas, New Mexico, Oklahoma, Texas, Wyoming.
→ 43
43. Corollas green, sometimes tinged pink or red, lobes 4.5–6 mm; corona segments 3.5–4.5 mm; follicles 1.5–2 cm wide, rugose.
A. involucrata
43. Corollas red-violet, lobes 3–5 mm; corona segments 1–2 mm; follicles 0.8–1.5 cm wide, smooth.
A. uncialis
42. Stems 15–70 cm; petioles 0–2 mm; peduncles 0–6 cm; follicles narrowly fusiform, 7.5–13.5 cm; se United States.
→ 44
44. Leaf blades scabridulous to puberulent with curved trichomes; corona segments laminar, 2–2.5 mm, appendage absent or obscure; fruiting pedicels upcurved; follicles 0.7–1.2 cm wide; seeds 11–12 × 7–8 mm.
A. longifolia
44. Leaf blades glabrous; corona segments cupulate, 2.5–3.5 mm, appendage falcate, well exserted from cavity; fruiting pedicels straight; follicles 0.5–0.7 cm wide; seeds 7–8 × 5–6 mm.
A. michauxii
41. Stems ascending to erect.
→ 45
45. Subshrubs, usually persistently woody at base (sometimes herbaceous to base), cespitose; stems 5–20+, sparsely to densely branched, at least at base.
→ 46
46. Stems 20–60 cm; petioles 2–4 mm; flowers 3–15 per umbel; corollas cream, sometimes tinged or striped pink; corona segments tubular, glabrous at apex, appendage acicular, arching over style apex, glabrous; fruiting pedicels straight.
A. angustifolia
46. Stems 5–35 cm; leaves sessile; flowers 1–7 per umbel; corollas greenish cream or greenish yellow, sometimes tinged red or purple; corona segments conduplicate or chute-shaped, hirtellous at apex, appendage falcate, arching over style apex, or an included crest, hirtellous; fruiting pedicel upcurved.
→ 47
47. Flowers 2–7 per umbel; anthers 1–1.5 mm; corona segments conduplicate, 4–5 mm, apex long-caudate, appendage falcate, exserted.
A. macrotis
47. Flowers 1–2 per umbel; anthers 1.5–2 mm; corona segments chute-shaped, sharply inflexed, 2–3 mm, apex subcaudate, appendage an included crest.
A. sperryi
45. Herbs, not woody at base; stems 1(–5), rarely branched (often branched in A. linearis).
→ 48
48. Corona segments strongly dorsally compressed or chute-shaped, margins incurved, appendages absent or a low, inlcuded crest; follicles 1–2 cm wide.
→ 49
49. Flowers 9-28 per umbel; pedicels puberulent with curved trichomes to pilosulous, straight in fruit; corona segments equaling style apex.
A. stenophylla
49. Flowers 34-112 per umbel; pedicels hirtellous, upcurved in fruit; corona segments greatly exceeded by style apex.
A. hirtella
48. Corona segments conduplicate or cupulate (may be slightly flattened dorsally, but not compressed), margins not incurved, appendages evident and exserted from cavity; follicles 0.3–1 cm wide.
→ 50
50. Corona segment appendages acicular, subulate, or falcate, exserted and inflexed towards or over style apex.
→ 51
51. Stems 60–125 cm; leaf blades 7–25 cm; corollas red, lobes 9–10 mm; corona segments yellow to reddish orange, 5–6 mm; fruiting pedicels upcurved.
A. lanceolata
51. Stems 25–75 cm; leaf blades 3–9 cm; corollas green, tan, or pink, sometimes tinged brown or red, lobes 3–5 mm; coronas cream, sometimes tinged brown or green, segments 1.5–4 mm; fruiting pedicels straight.
→ 52
52. Plants rhizomatous; interpetiolar ridges present; pedicels 6–8 mm; corona segments 1.5 mm; follicles 5–8.5 cm; Texas.
A. linearis
52. Plants not rhizomatous; interpetiolar ridges absent; pedicels 7–13 mm; corona segments 3–4 mm; follicles 9–12.5 cm; Alabama, Florida.
A. viridula
50. Corona segment appendages crestlike, included, or absent.
→ 53
53. Corollas and coronas yellowish green to green; corolla lobes erect, concealing gynostegium and partially obscuring corona; corona appendages absent; follicles densely puberulent with curved trichomes.
A. pedicellata
53. Corollas green, white, or cream, sometimes tinged gray, pink, red, lavender, or purple, lobes reflexed or spreading; coronas red, pink, violet, white, cream, gray, or a combination of these, appendage crestlike, included; follicles glabrous, glabrate, or pilosulous.
→ 54
54. Corollas green, sometimes tinged red, lobes pilose abaxially; anthers tan to brown; coronas red, pink, purple, or red-violet, sometimes white at segment apices; fruiting pedicels upcurved, follicles pilosulous to glabrate; s Arizona, s New Mexico.
A. quinquedentata
54. Corollas cream or white, tinged gray, pink, lavender, or purple, lobes glabrous; anthers green or lavender; corona segments cream or white, sometimes tinged gray, pink, or purple; fruiting pedicels straight, follicles glabrous; se United States.
→ 55
55. Flowers erect; corollas white, sometimes tinged lavender, lobes spreading, 7–10 mm; anthers lavender; corona segments white, cupulate, apex edentate.
A. feayi
55. Flowers spreading to pendent; corollas and coronas cream, tinged gray, pink, or purple; corolla lobes reflexed, 4–5 mm; anthers green; corona segments conduplicate, apex toothed laterally.
A. cinerea
38. Leaf blades linear, elliptic, oblong, oval, lanceolate, ovate, deltate, oblanceolate, obovate, oblate, or orbiculate, 0.1–15 cm wide.
→ 56
56. Both stems and leaf blades completely glabrous or glabrate, except for ciliate leaf margins in some species or abaxial midvein (A. cryptoceras).
→ 57
57. Stems and/or leaf blades glaucous.
→ 58
58. Corona segment appendages merely low, included crests or absent; w United States, w of Rocky Mountains plus Arizona, New Mexico, w Texas.
→ 59
59. Corollas red-violet, lobes 6–7 mm; corona segments tubular, 2–3 mm; n California, extreme w Nevada, sw Oregon.
A. cordifolia
59. Corollas green to yellowish green, sometimes tinged red abaxially, lobes 8–14 mm; corona segments conduplicate, 4–8 mm; Arizona, e California, w Colorado, Idaho, Nevada, s New Mexico, e Oregon, w Texas, Utah, e Washington, s Wyoming.
→ 60
60. Stems prostrate to decumbent, 8–25 cm; umbels sessile; corolla lobe apices minutely hirtellous adaxially; anthers brown (sometimes with green apex), 1.8–3 mm; corona segments red-violet to pinkish purple, apex with recurved, papillose teeth, appendage absent; follicles 4.5–6 cm, glabrous, glaucous.
A. cryptoceras
60. Stems erect, 30–80 cm; peduncles 5–20 cm; corolla lobes glabrous; anthers green, 3–3.5 mm; corona segments white, yellow to tan dorsally, apex edentate, appendage a low, included crest; follicles 8–13 cm, pilosulous, not glaucous.
A. elata
58. Corona segment appendages exserted, falcate, subulate, or ensiform; e United States, w to Arizona, Colorado, Kansas, Nebraska, New Mexico, Texas, Utah.
→ 61
61. Peduncles, pedicels, calyx lobes, and developing leaf blades tomentose, leaves becoming glabrate with age; w United States, plains e of Rocky Mountains to c Kansas, c Nebraska, c Oklahoma, w Texas.
A. latifolia
61. Peduncles, pedicels, calyx lobes, and developing leaf blades glabrous, puberulent with curved trichomes, or pilosulous; e United States and Canada, w to e Kansas, e Nebraska, c Oklahoma, and e Texas.
→ 62
62. Stems decumbent to erect; corolla lobes 5.5–6 mm; anthers brown; corona segments 3–3.5 mm, appendage ensiform, only slightly exserted.
A. humistrata
62. Stems erect; corolla lobes 7–12 mm; anthers green; corona segments 4–7 mm, appendage falcate or subulate, well exserted.
→ 63
63. Leaf blades 1.5–9 cm wide, apex obtuse, rounded, truncate, or emarginate (acute); pedicels 20–55 mm; anthers 2.5–3.5 mm; corona segments tubular, apex broadly obtuse and oblique or truncate and erose; follicles 1–3 cm wide.
→ 64
64. Peduncles 5–40 cm; flowers 18–53 per umbel; pedicels puberulent with curved trichomes; corollas green, often tinged reddish purple, or bronze; coronas reddish purple to cream, segments stipitate, apex truncate, erose; follicles smooth, 9–16 cm; seeds 9–10 × 6–7 mm.
A. amplexicaulis
64. Peduncles 1–6 cm; flowers 9–29 per umbel; pedicels glabrous, glaucous; corollas dark pink, pale at base of lobes; coronas pale to dark pink, segments subsessile, apex broadly obtuse, oblique; follicles sparsely muricate, 7–11 cm; seeds 7–9 × 5–6 mm.
A. sullivantii
63. Leaf blades 1–5 cm wide, apex acute to attenuate; pedicels 11–20 mm; anthers 2–2.5 mm; corona segments conduplicate, apex acute to obtuse and emarginate; follicles 0.9–1.6 cm wide.
→ 65
65. Leaves sessile, blade base rounded to obtuse; flowers pendent; corollas green to greenish cream, sometimes tinged red; coronas green to yellowish green or greenish cream, segments sessile, apex obtuse, emarginate, appendage falcate, sharply inflexed towards style apex; seeds 6–7 × 4–5 mm; Illinois, Indiana, Iowa, Kansas, Missouri, Wisconsin.
A. meadii
65. Petioles 1–2 mm; leaf blade bases cordate; flowers erect; corollas pink to reddish purple; coronas pink to lavender, segments stipitate, apex acute, appendage subulate, arching above style apex; seeds 7–9 × 5–7 mm; coastal plain, e United States to e Texas.
A. rubra
57. Neither stems nor leaf blades glaucous.
→ 66
66. Leaf blades 0.1–2 cm wide.
→ 67
67. Stems 10–60 cm; corolla lobes 1.5–6 mm; corona segments 1.5–4 mm.
→ 68
68. Leaf blades linear, 0.2–0.6 cm wide; flowers 4–10 per umbel; corollas green, sometimes tinged red, lobes pilose abaxially; corona segment apices truncate, appendage crestlike, barely exserted; fruiting pedicels upcurved; seeds 4–5 × 3–4 mm; s Arizona, s New Mexico.
A. quinquedentata
68. Leaf blades linear to elliptic, oval, oblong, or ovate, 0.3–6 cm wide; flowers 7–31 per umbel; corollas white, cream, or pink, lobes glabrous abaxially; corona segment apices obtuse to acute, appendage acicular or subulate, well exserted; fruiting pedicels straight or declined; seeds 6–15 × 4–14 mm; e United States and Canada to e Texas.
→ 69
69. Subshrubs or herbs; stems cespitose; interpetiolar ridges present; petioles 10–12 mm; pedicels 7–13 mm; flowers erect to spreading; corolla lobes 3–4 mm; corona segments tubular, rounded dorsally, 1.5–2.5 mm, appendage acicular, arching above style apex; fruiting pedicels declined, follicles pendulous, 4–7 × 1–2.5 cm; seeds 12–15 × 11–14 mm, coma absent.
A. perennis
69. Herbs; stems solitary; interpetiolar ridges absent; petioles 2–7 mm; pedicels 17–28 mm; flowers spreading to pendent; corolla lobes 4–5 mm; corona segments conduplicate, flattened dorsally, 2.5–4 mm, appendage subulate, inflexed over style apex; fruiting pedicels straight, follicles erect, 8–16 × 0.4–1 cm; seeds 6–7 × 4–5 mm, coma present.
A. quadrifolia
67. Stems 25–125 cm; corolla lobes 7–13 mm; corona segments 5–10 mm.
→ 70
70. Leaf blades 2.5–8 cm; flowers spreading to pendent; corollas green, sometimes tinged brown at lobe tips, lobes 10–13 mm; anthers 3–3.5 mm; corona segments cream to pale green, 8–10 mm, clavate, incurved, appendage an included crest; follicles 11.5–15 cm.
A. connivens
70. Leaf blades 5–25 cm; flowers erect; corollas red, pink, or reddish purple, lobes 7–10 mm; anthers 2–2.5 mm; corona segments yellow, reddish orange, pink, or lavender, 5–7 mm, tubular or conduplicate, appendage subulate, well exserted; follicles 5.5–12 cm.
→ 71
71. Petioles 0–1 mm; leaf blades linear to linear-lanceolate, 0.2–1.7 cm wide, base cuneate; flowers 4–16 per umbel; corollas red, lobes 9–10 mm; corona segments yellow to reddish orange, tubular, apex obtuse, 5–6 mm, appendage sharply inflexed over style apex; follicles 0.8–1 cm wide.
A. lanceolata
71. Petioles 1–2 mm; leaf blades narrowly lanceolate to ovate, 1–4.5 cm wide, base cordate; flowers 9–20 per umbel; corollas pink to reddish purple, lobes 7–9 mm; corona segments pink to lavender, conduplicate, apex acute, 6–7 mm, appendage arching above style apex; follicles 1–1.5 cm wide.
A. rubra
66. Leaf blades 2–15 cm wide.
→ 72
72. Leaf blade bases cuneate.
→ 73
73. Petioles 0–1 mm; leaf blades linear to narrowly elliptic or oblanceolate, 0.3–2.5 cm wide; flowers 4–8 per umbel; pedicels 10–20 mm; corolla lobes 10–13 mm; corona segments 8–10 mm, clavate, appendage an included crest; coastal plain, s Alabama, Florida, s Georgia, se South Carolina.
A. connivens
73. Petioles 2–15 mm; leaf blades ovate to elliptic or oblong, 1–11 cm wide; flowers 7–41 per umbel; pedicels 17–45 mm; corolla lobes 4–12 mm; corona segments 2.5–5 mm, tubular or conduplicate, appendage subulate or falcate, well exserted; inland e North America, including n Alabama, n Georgia, w South Carolina.
→ 74
74. Stems 25–60 cm; petioles 2–7 mm; leaf blades 2.5–12 × 1–6 cm; pedicels 17–28 mm; corollas pink or cream, lobes 4–5 mm; anthers tan to brown, 1–1.5 mm; corona segments conduplicate, apex obtuse, appendage subulate; follicles 0.4–1 cm wide; seeds 6–7 mm.
A. quadrifolia
74. Stems 65–150 cm; petioles 5–15 mm; leaf blades 10–24 × 2–11 cm; pedicels 25–45 mm; corollas green (rarely pink-tinged), lobes 6–12 mm; anthers green, 2.5–3.5 mm; corona segments tubular, apex truncate, appendage falcate; follicles 1.5–2 cm wide; seeds 8–10 mm.
A. exaltata
72. Leaf blade bases truncate or rounded to cordate.
→ 75
75. Peduncles and pedicels puberulent with curved trichomes in 1 line; flowers 9–20 per umbel; corollas pink to reddish purple; coronas pink to lavender, 6–7 mm, segment apices acute; follicles fusiform, 1–1.5 cm wide; coastal plain, e United States to e Texas.
A. rubra
75. Peduncles tomentose, puberulent with curved trichomes, or pilosulous; pedicels tomentose or densely pilose to glabrate; flowers 12–80 per umbel; corollas green, ochroleucous, tan, or red-violet; coronas cream to ochroleucous, 2.5–5.5 mm, segment apices truncate; follicles lance-ovoid to ovoid or ellipsoid, 1.7–3.5 cm wide; w United States.
→ 76
76. Stems 40–250 cm; leaf blades 7.5–25 cm, apex attenuate to acuminate, margins erose; umbels terminal and extra-axillary; corolla lobe apices tomentose abaxially; seeds 8–13 mm; Sonoran and Mohave deserts and surrounding areas, w Arizona, s California, s Nevada, sw Utah.
A. erosa
76. Stems 25–100 cm; leaf blades 4.5–14.5 cm, apex truncate to rounded (sometimes acute), margins entire; umbels extra-axillary; corolla lobes densely tomentose throughout abaxially or glabrous; seeds 7–8 mm or 18–20 mm; e of the Sonoran and Mohave deserts, ne Arizona, s Utah to the Great Plains.
→ 77
77. Peduncles 0–2.5 cm, puberulent with curved trichomes or pilosulous; pedicels 15–35 mm; corollas green, lobes 7–9 mm, glabrous abaxially; anthers 3–3.5 mm; corona segments 3–5.5 mm, apex papillose; fruiting pedicels upcurved; seeds 7–8 × 5–6 mm; ne Arizona, s Utah to the Great Plains, substrates various including sand.
A. latifolia
77. Peduncles 2.5–6 cm, tomentose; pedicels 10–15 mm; corollas ochroleucous or tan to red-violet, lobes 5.5–6.5 mm, tomentose abaxially; anthers 1.5 mm; corona segments 2.5–3.5 mm, apex glabrous; fruiting pedicels spreading; seeds 18–20 × 9–10 mm; local and rare in n Arizona, s Utah on unstabilized sand dunes.
A. welshii
56. Either stems and/or leaf blades bearing trichomes, sometimes restricted to veins.
→ 78
78. Stems prostrate or decumbent.
→ 79
79. Stems 5–15 cm.
→ 80
80. Leaf blades 1.7–5 cm; corollas green, sometimes tinged red, pink, or brown; corona segments 2–10 mm; follicles 4.5–9.5 × 1.2–2.5 cm.
→ 81
81. Leaf blades 1.2–6.5 cm wide, apex obtuse to rounded; umbels extra-axillary; corolla lobes 7–12 mm; anthers 2–2.5 mm; corona segments green, sometimes tinged bronze, apex white or cream, sinuous-tubular, 5–10 mm.
A. oenotheroides
81. Leaf blades 0.2–2 cm wide, apex acute to attenuate; umbels terminal; corolla lobes 4.5–6.5 mm; anthers 1–2 mm; corona segments cream with pink or red dorsal stripe or yellow to ochroleucous, conduplicate or tubular, but not sinuous, 2–4.5 mm.
→ 82
82. Leaf blades 0.2–0.8 cm wide; anthers 1.5–2 mm; corona segments cream, usually with a pink or red dorsal stripe, conduplicate, 3.5–4.5 mm; seeds 7–8 × 5–6 mm.
A. involucrata
82. Leaf blades 0.5–2 cm wide; anthers 1–1.5 mm; corona segments yellow to ochroleucous, tubular, 2–3 mm; seeds 8–12 × 6–8 mm.
A. macrosperma
80. Leaf blades 1.5–12 cm; corollas red-violet; corona segments 1–2 mm; follicles 3–6 × 0.5–1.5 cm.
→ 83
83. Corona segment appendages falcate, not or barely exserted; Colorado Plateau, ne Arizona, nw New Mexico, Utah.
→ 84
84. Leaf blades persistently pilosulous, more densely so on veins; pedicels and calyces densely pilosulous to tomentulose; corona segment appendages included; Utah, n of Colorado River and w of Green River, from San Rafael Reef to Waterpocket Fold.
A. ruthiae
84. Leaf blades sparsely pilosulous to glabrate, persistently and densely hairy on veins and margins; pedicels and calyces pilosulous; corona segment appendages barely exserted; ne Arizona, nw New Mexico, just entering Utah in Monument Valley.
A. sanjuanensis
83. Corona segment appendages lingulate or conical, barely exserted; Arizona, Colorado, Nevada, New Mexico, w Oklahoma, w Texas, not on the Colorado Plateau.
→ 85
85. Leaf blades lanceolate to ovate, 0.6–3 cm wide, strigulose or pilosulous on midvein to glabrate; flowers 2–25 per umbel; anthers 1.5–2 mm; corona appendages conical; Nevada.
A. eastwoodiana
85. Leaf blades linear to lanceolate, 0.2–1 cm wide, puberulent with curved trichomes on midvein; flowers 3–7 per umbel; anthers 1–1.5 mm; corona appendages lingulate; Arizona, Colorado, New Mexico, w Oklahoma, w Texas.
A. uncialis
79. Stems 15–250 cm.
→ 86
86. Leaf blades 0.1–1 cm wide.
→ 87
87. Corolla lobes 8–11 mm, pilosulous abaxially; corona segments 5–7 mm, appendage papillose; follicles muricate ridged; s Texas.
A. prostrata
87. Corolla lobes 3–6 mm, glabrous abaxially; corona segments 1.5–4.5 mm, appendage glabrous; follicles smooth or rugose; widespread, but not s Texas.
→ 88
88. Stems 25–70 cm; corona segments laminar, margins incurved, append­age absent or obscure; follicles 8–13.5 × 0.7–1.2 cm.
A. longifolia
88. Stems 5–30 cm; corona segments cupulate or conduplicate, margins not incurved, appendage conical or falcate, barely to well exserted; follicles 3.5–6 × 0.5–2 cm or 7.5–12.5 × 0.5–0.7 cm.
→ 89
89. Corollas red-violet; corona segments 1.5–2 mm, appendage conical, barely exserted, follicles spreading to pendulous, strigose.
A. eastwoodiana
89. Corollas green to tan, sometimes tinged pink or red; corona segments 2.5–4.5 mm, appendage falcate, well exserted, sharply inflexed over style apex; follicles erect, puberulent with curved trichomes to pilosulous.
→ 90
90. Stems 5–18 cm; anthers brown; corona segments conduplicate, apex truncate, 3.5–4.5 mm; fruiting pedicels upcurved, fol­licles ovoid, rugose, 4.5–5.5 × 1.5–2 cm; c United States.
A. involucrata
90. Stems 15–30 cm; anthers green; corona segments cupulate, apex obtuse, 2.5–3.5 mm; fruiting pedicels straight, follicles narrowly fusiform, smooth, 7.5–12.5 × 0.5–0.7 cm; se United States.
A. michauxii
86. Leaf blades 1–15 cm wide.
→ 91
91. Corona segments 5–11 mm, greatly exceeding style apex, tubular, sinuous-tubular, or conduplicate-tubular, appendage papillose (rarely glabrous or glabrate).
→ 92
92. Stems, leaf blades, peduncles, and pedicels pilosulous to tomentulose; petioles 2–3 mm, leaf blades 1.8–5 × 0.4–1.8 cm; flowers 3–8 per umbel; pedicels 8–14 mm; gynostegial column 3–3.5 mm; follicles pendent, muricate-ridged, tomentulose.
A. prostrata
92. Stems, leaf blades, peduncles, and pedicels puberulent with curved trichomes or hirtellous; petioles 2–25 mm; leaf blades 4–15 × 1.2–7.5 cm; flowers 5–32 per umbel; pedicels 10–30 mm; gynostegial column 0.3–1.5 mm; follicles erect, smooth, puberulent with curved trichomes or hirtellous.
→ 93
93. Leaf blades ovate or lanceolate to oblong or elliptic, base cuneate to obtuse, apex obtuse to rounded, sometimes conduplicate; pedicels 10–20 mm; gynostegial column 1–1.5 mm; anthers 2–2.5 mm; corona segments relatively slender, green, sometimes tinged bronze, apex white or cream, deeply emarginate; se Arizona, sw Colorado, w Louisiana, New Mexico, Oklahoma, Texas.
A. oenotheroides
93. Leaf blades ovate to lanceolate, base cuneate or obtuse to truncate or sub­cordate, apex obtuse to acute, rarely conduplicate; pedicels 17–30 mm; gyno­stegial column 0.3–0.5 mm; anthers 1.7–2 mm; corona segments relatively stout, cream or green with cream apex, apex truncate; Arizona, se California, s Nevada, sw New Mexico.
A. nyctaginifolia
91. Corona segments 1.5–6 mm, shorter than to slightly exceeding style apex, cupulate or conduplicate, appendage glabrous.
→ 94
94. Corolla lobes 4–6 mm; corona segments 1.5–3 mm.
→ 95
95. Leaf blades ovate to nearly orbiculate, 3–4 cm wide, base obtuse to cordate; flowers 20–55 per umbel; corolla lobes 5–6 mm; corona segments conduplicate, 2–3 mm, appendage absent; follicles 6–10 × 2–3 cm.
A. solanoana
95. Leaf blades narrowly lanceolate to ovate, 0.6–3 cm wide, base cuneate to obtuse; flowers 2–25 per umbel; corolla lobes 4–5 mm; corona segments cupulate, 1.5–2 mm, appendage conical, barely exserted; follicles 3.5–6 × 0.5–1 cm; Nevada.
A. eastwoodiana
94. Corolla lobes 6–11 mm; corona segments 3–6 mm.
→ 96
96. Flowers 5–21 per umbel; corolla lobes pilose at base adaxially; gynostegial column 2–3.5 mm; corona segments red-violet, margins connivent, papillose, appendage absent.
A. californica
96. Flowers 12–50 per umbel; corolla lobes papillose or glabrous at base adaxially; gynostegial column 1–1.5 mm; corona segments cream to ochroleucous or dark pink, margins separate, glabrous, appendage falcate.
→ 97
97. Petioles 3–10 mm; leaf blade margins entire; peduncles 0–3.5 cm; corolla lobes densely tomentose abaxially throughout; anthers dark brown, 1.5–2 mm; corona segments sessile, apex obtuse, oblique; follicles 5–6.5 cm.
A. vestita
97. Petioles 0–6 mm; leaf blade margins erose; peduncles 2–10 cm; corolla lobes tomentose abaxially only at tips; anthers green, 2.5–3 mm; corona segments stipitate, apex truncate; follicles 6.5–10 cm.
A. erosa
78. Stems spreading to erect.
→ 98
98. Corolla lobes 3–5 mm.
→ 99
99. Corona segments laminar or chute-shaped, margins incurved, tightly appressed to gynostegium; appendage absent or obscure.
→ 100
100. Stems 7–20 cm; leaf blades oblong or lanceolate to narrowly lanceolate, 4–8 cm, hirtellous; umbels terminal; anthers 1.5–2 mm; seeds 6–7 × 4–5 mm.
A. lanuginosa
100. Stems 25–70 cm; leaf blades linear to linear-lanceolate, 4–18 cm, scabrid­ulous to puberulent with curved trichomes; umbels terminal and/or extra-axillary; anthers 1–1.5 mm; seeds 10–12 × 7–8 mm.
→ 101
101. Flowers 34–112 per umbel; pedicels and calyces hirtellous; corona segments 1.5–2 mm, not exceeding point of anther wings; follicles 1–2 cm wide.
A. hirtella
101. Flowers 13–28(–36) per umbel; pedicels and calyces puberulent with curved trichomes; corona segments 2–2.5 mm, exceeding point of anther wings; follicles 0.7–1.2 cm wide.
A. longifolia
99. Corona segments conduplicate, cupulate, or tubular, margins not incurved, not appressed to gynostegium; appendage falcate, acicular, subulate, conical, lingulate, or crestlike, barely to well exserted.
→ 102
102. Stems, leaf blades, and peduncles tomentose, at least initially.
→ 103
103. Stems 6–15 cm; leaf blades orbiculate to obovate or oblate, 1.5–3.2 × 1.7–4 cm; peduncles 2.7–6 cm; corolla lobes glabrous abaxially; anthers 1–1.5 mm; corona segments conduplicate, appendage fal­cate; follicles smooth.
A. nummularia
103. Stems 20–40 cm; leaf blades linear-lanceolate, 5–15 × 0.3–1.3 cm; peduncles 0.2–1.5 cm; corolla lobes minutely pilosulous abaxially; anthers 2–2.5 mm; corona segments tubular, appendage lingulate; follicles ribbed.
A. brachystephana
102. Stems, leaf blades, peduncles, pedicels, and calyces puberulent with curved trichomes, pilose, strigulose, hirtellous, or glabrous.
→ 104
104. Leaf blades linear, 0.1–0.8 cm wide.
→ 105
105. Flowers pendent to spreading; corolla lobes pilose abaxially; corona segments conduplicate, sessile, apex truncate, append­age crestlike, barely exserted; fruiting pedicels upcurved.
A. quinquedentata
105. Flowers erect; corolla lobes glabrous abaxially; corona seg­ments tubular or cupulate, stipitate, apex obtuse, appendage falcate or acicular, well exserted; fruiting pedicels straight.
→ 106
106. Stems few–numerous, 20–60 cm; leaf blades spreading, not secund, midvein puberulent with curved trichomes; umbels all extra-axillary; corollas cream, sometimes tinged or striped pink; anthers brown; corona segments tubular, appendage acicular, arching above style apex; follicles glabrous; se Arizona.
A. angustifolia
106. Stems 1–4 (rarely more), 15–30 cm; leaf blades ascending, appearing secund, midvein glabrous; umbels terminal, some­times also extra-axillary; corollas green to tan, tinged pink or red; anthers green; corona segments cupu­late, appendage fal­cate, sharply inflexed over style apex; follicles minutely puber­ulent with curved trichomes; se United States.
A. michauxii
104. Leaf blades narrowly elliptic, oval, oblong, lanceolate, ovate, oblanceolate, or obovate, 0.3–6 cm wide.
→ 107
107. Corollas white, pink, or cream; corona segment appendages acicular or subulate.
→ 108
108. Interpetiolar ridges absent; petioles 2–7 mm; leaf blades 1–6 cm wide; umbels terminal (sometimes also extra-axillary); flowers spreading to pendent; pedicels 17–28 mm; corona segments conduplicate, sessile, appendage subulate.
A. quadrifolia
108. Interpetiolar ridges present; petioles 5–20 mm; leaf blades 0.3–3 cm wide; umbels extra-axillary (may appear terminal); flowers erect to spreading; pedicels 7–14 mm; corona segments cupulate or tubular, stipitate, appendage acicular.
→ 109
109. Leaf blades narrowly elliptic to oval or oblong, 5–14 cm; corona segments tubular, 1.5–2.5 mm; follicles pendulous on deflexed pedicels, lance-ovoid, 4–7 × 1–2.5 cm; seeds 12–15 × 11–14 mm, coma absent; bottomlands and ditches, e United States to e Texas.
A. perennis
109. Leaf blades ovate to lanceolate or elliptic, 2–7 cm; corona segments cupulate, 2–3 mm; follicles erect on straight pedicels, narrowly fusiform, 9–13 × 0.5–1 cm; seeds 6–7 × 4–5 mm, coma present; canyons and slopes; c, w Texas.
A. texana
107. Corollas green, sometimes tinged red, purple, or bronze, or red-violet; corona segment appendages falcate or conical.
→ 110
110. Corollas red-violet; corona segments cupulate, 1.5–2 mm, appendage conical, barely exserted; fruiting pedicels spreading, follicles spreading to pendulous, lance-ovoid, 3.5–6 cm, strigose; Nevada.
A. eastwoodiana
110. Corollas green, tinged purple or bronze, rarely reddish purple; corona segments tubular or conduplicate, 2–6 mm, appendage falcate, well exserted; fruiting pedicels upcurved, follicles erect, fusiform, 5–10.5 cm, pilosulous or puberulent with curved trichomes; Florida or w Texas.
→ 111
111. Stems 15–20 cm, pilosulous; leaf blades 6–8 cm, sparsely hirtellous, mar­gins crisped; umbels terminal; peduncles 7–17 cm; pedicels 15–20 mm, pilose; anthers brown, 1.5–2 mm; corona segments tubular, 2–3 mm, apex truncate; w Texas.
A. scaposa
111. Stems 15–100 cm, puberulent with curved trichomes; leaf blades 1.8–5 cm, sparsely puberulent with curved trichomes on midvein only, margins entire; umbels terminal and extra-axillary; peduncles 0–4 cm; pedicels 10–14 mm, sparsely puberulent with curved trichomes; anthers green, 1–1.5 mm; corona segments conduplicate, 5–6 mm, apex attenuate; Florida.
A. curtissii
98. Corolla lobes 5–15 mm (rarely 4.5 mm in A. incarnata, with corolla and corona pink to white, corona segments 2–2.5 mm, and fruiting pedicels straight).
→ 112
112. Stems, leaf blades, peduncles, or pedicels persistently tomentose or tomentulose.
→ 113
113. Corona segments 7–15 mm.
→ 114
114. Petioles 2–6 mm; leaf blade surfaces adaxially pilosulous or tomentulose to glabrate, abaxially tomentose; corolla lobes deep maroon to green adaxially, glabrous adaxially; anthers 2–2.5 mm; coronas deep maroon to yellowish green, segments 7–9 mm, appendage absent or merely a low crest; follicles fusiform, 1.2–1.4 cm wide; extreme se Arizona and sw New Mexico.
A. hypoleuca
114. Petioles 4–12 mm; leaf blade surfaces uniformly green, tomentose to pilose; corolla lobes dark pink (rarely pale), hirtellous at base adaxially; anthers 2.5–3 mm; coronas pale pink to nearly cream, segments 9–15 mm, appendage subulate, sharply inflexed over style apex; follicles lance-ovoid, 2–3 cm wide; widespread in w United States and Canada, but not in se Arizona and sw New Mexico.
A. speciosa
113. Corona segments 2–7 mm.
→ 115
115. Corolla lobes glabrous abaxially.
→ 116
116. Corollas pink, red green, or pinkish green, or reddish green; anthers brown; corona segments cream with red, pink, or purple dorsal stripe, apex acute, appendage glabrous; Rocky Mountains and associated alluvial plains, 1700–3000 m.
A. hallii
116. Corollas green to yellowish green, sometimes tinged red or purple; anthers green; corona segments green with cream apex, sometimes tinged pink or purple, or cream, greenish cream, or ochroleucous, not striped red, pink, or purple, apex truncate to rounded, appendage papillose; se United States, Great Plains, or Colorado Plateau, to 2300 m.
→ 117
117. Corona segments green with cream apex, sometimes tinged pink or purple; corona segment apices glabrous; follicles fusiform to narrowly lance-ovoid, 1–1.5 cm wide; se United States and e Texas.
A. tomentosa
117. Corona segments cream to greenish cream or ochroleucous, apices papillose; follicles lance-ovoid to ovoid, 2–3 cm wide; Great Plains and Colorado Plateau to e Texas.
→ 118
118. Petioles 7–17 mm; leaf blade bases rounded, truncate, or subcordate; anthers 2–2.5 mm; corona segment apices truncate to rounded, emarginate, not oblique, appendage apex upturned; seeds 9–12 × 6–8 mm.
A. arenaria
118. Petioles 0–4 mm; leaf blade bases cordate; anthers 3–3.5 mm; corona segment apices truncate, not emarginate, oblique, appendage apex not upturned; seeds 7–8 × 5–6 mm.
A. latifolia
115. Corolla lobes pilose, pilosulous, or tomentose abaxially, at least at tips.
→ 119
119. Leaf blades linear-lanceolate, 0.3–1.3 cm wide; corolla lobes 4–6 mm; corona segments 1.5–2 mm; follicles conspicuously striate.
A. brachystephana
119. Leaf blades ovate or oval to lanceolate, elliptic, oblong, or obovate, 1.5–15 cm wide; corolla lobes 5–11 mm; corona segments 2.5–6 mm; follicles not striate.
→ 120
120. Corolla lobes pilose at base adaxially; gynostegial column 2–3.5 mm; corona segments red-violet, dorsally convex from base to apex, margins connivent, appendage absent.
A. californica
120. Corolla lobes glabrous, minutely hirtellous, or papillose at base adaxially; gynostegial column 0.2–1.5 mm; corona segments cream or ochroleucous to dark pink (sometimes reddish purple in A. syriaca), dorsally straight or concave from base to apex, margins separate, appendage falcate or acicular.
→ 121
121. Leaf blades 3–9 × 1.5–4.5 cm, pilosulous; flowers 5–21 per umbel; s Canada (Alberta to Ontario), n United States (Montana and Wyoming e to Illinois and Michigan).
A. ovalifolia
121. Leaf blades 6–30 × 2–15 cm, tomentose or puberulent with curved trichomes to glabrate (sometimes pilosulous in A. syriaca); flowers 12–113 per umbel; Arizona, California, Nevada, and Utah, or widespread in e United States and Canada, w to Manitoba, North Dakota, and South Dakota (A. syriaca).
→ 122
122. Pedicels 10–15 cm; corona appendages acicular; fruiting pedicels spreading, follicles pendulous; extreme n Arizona and s Utah.
A. welshii
122. Pedicels 15–50 cm; corona appendages falcate; fruiting pedicels upcurved, follicles erect; w Arizona, California, s Nevada, and sw Utah, or e United States and Canada.
→ 123
123. Pedicels pilose to puberulent with curved trichomes; corona segments slightly flattened dorsally, apex obtuse and usually flared, not oblique; follicles muricate (less commonly smooth); e United States and Canada.
A. syriaca
123. Pedicels tomentose to glabrate; corona segments rounded dorsally, apex truncate or obtuse and oblique, not flared; follicles smooth or longitudinally ridged; Arizona, California, Nevada, and Utah.
→ 124
124. Peduncles 0–3.5 cm; corolla lobes tomentose abaxially throughout; anthers 1.5–2 mm; corona segments sessile, apex obtuse; follicles ovoid, 5–6.5 cm, ridged.
A. vestita
124. Peduncles 1–10 cm; corolla lobes tomentose abaxially only at tips; anthers 2.5–3 mm; corona segments stipitate, apex truncate; follicles lance-ovoid to ovoid, 5–10 cm, smooth.
→ 125
125. Petioles 0–6 mm; leaf blade margins erose; corollas green; anthers green; coronas cream to ochroleucous, segment apices and appendages glabrous; follicles thinly tomentose; seeds 8–13 × 5–10 mm.
A. erosa
125. Petioles 4–15 mm; leaf blade margins entire or undulate; corollas greenish cream, ochroleucous, pink, tan, or pinkish cream; anthers dark brown; coronas cream to dark pink, segment apices and appendages papillose; follicles densely tomentose, seeds 7–9 × 4–6 mm.
A. eriocarpa
112. Stems, leaf blades, peduncles, and pedicels variously indumented, sometimes ephemerally tomentose or tomentulose.
→ 126
126. Stems, leaf blades, peduncles, and pedicels hirsute or hirtellous.
→ 127
127. Stems 100–150 cm; leaf blades 3–14 cm wide; umbels terminal and extra-axillary; peduncles 6–13 cm; flowers 21–53 per umbel; corollas cream to greenish cream or ochroleucous, sometimes tinged pink; corona segments conduplicate; se Arizona.
A. lemmonii
127. Stems 6–70 cm (rarely to 200 cm in A. obovata); leaf blades 0.4–7.5 cm wide; umbels extra-axillary (sometimes appearing terminal); peduncles 0–2 cm; flowers 4–32 per umbel; corollas green, sometimes tinged red, purple, brown, or bronze; corona segments tubular; s United States, including se Arizona.
→ 128
128. Stems 40–70(–200) cm; flowers erect to pendent; anthers 2.5–4 mm; corona segments bronze or yellow, often tinged red, sometimes paler or cream at apex, appendage falcate, glabrous; seeds 8–9 × 6–7 mm; s Canada (Alberta to Ontario), n United States (Montana and Wyoming e to Illinois and Michigan).
A. obovata
128. Stems 6–50 cm; flowers erect to ascending; anthers 1–2.5 mm; corona segments cream or green with cream or white at apex, sometimes tinged bronze, appendage lingulate, papil­lose or glabrous; seeds 6–8 × 4.5–6.5 mm; California to w Louisiana, n to c Oklahoma.
→ 129
129. Leaf blades 0.4–2.5 cm wide, base cuneate; flowers 4–8 per umbel; corolla lobes 5–7 mm; anthers green, 1–1.5 mm; corona segments 3.5–5.5 mm, appendage flush with apex and obscuring cavity.
A. emoryi
129. Leaf blades 1.2–7.5 cm wide, base cuneate to subcordate; flowers 5–32 per umbel; corolla lobes 7–13 mm; anthers brown, sometimes green at base, 1.7–2.5 mm; corona segments (5–)7–11 mm, appendage exserted below apex, exposing cavity.
→ 130
130. Leaf blades ovate or lanceolate to oblong or elliptic, base cuneate to obtuse, apex obtuse to rounded, sometimes conduplicate; pedicels 10–20 mm; gynostegial column 1–1.5 mm; anthers 2–2.5 mm; corona segments green, sometimes tinged bronze, white or cream at apex, relatively slender, apex deeply emarginate; se Arizona, sw Colorado, w Louisiana, New Mexico, Oklahoma, Texas.
A. oenotheroides
130. Leaf blades ovate to lanceolate, base cuneate or obtuse to truncate or subcordate, apex obtuse to acute, rarely con­du­plicate; pedicels 17–30 mm; gynostegial column 0.3–0.5 mm; anthers 1.7–2 mm; corona segments cream or green with cream apex, relatively stout, apex truncate; Arizona, se California, s Nevada, sw New Mexico.
A. nyctaginifolia
126. Stems, leaf blades, peduncles, and pedicels variously indumented, but trichomes not straight and spreading.
→ 131
131. Corona appendages crestlike, included or barely exserted from segment, or absent.
→ 132
132. Corolla lobes 10–13 mm; corona segments clavate, 8–10 mm, greatly exceeding style apex, segment apices sometimes connivent.
A. connivens
132. Corolla lobes 4–10 mm; corona segments conduplicate or laminar with incurved margins, 1.5–4 mm, barely exceeding to greatly exceeded by style apex, segment apices separated by gynostegium.
→ 133
133. Leaf blades linear to broadly oval or nearly orbiculate, 0.8–6 cm wide; flowers 22–60 per umbel; anthers 3–4 mm; corona segments laminar, appressed to gynostegium, margins incurved; follicles fusiform to lance-ovoid, 1.5–2 cm wide.
A. viridiflora
133. Leaf blades linear to narrowly elliptic or narrowly lanceolate, 0.1–0.8 cm wide; flowers 2–10 per umbel; anthers 1–2 mm; corona conduplicate, margins not incurved, not appressed to gynostegium; follicles fusiform to lance-ovoid, 0.3–1 cm wide.
→ 134
134. Leaf blades linear, 6–14 cm; peduncles 1.1–2.7 cm; flowers pendent to spreading; pedicels 14–21 mm; corolla lobes reflexed, exposing corona, 4–6 mm, pilose abaxially; anthers tan to brown; corona segments red, pink, red-violet, or purple at base, white at apex, 3–4 mm; appendage crestlike, barely exserted; fruiting pedicels upcurved, follicles 0.5–1 cm wide, pilosulous to glabrate.
A. quinquedentata
134. Leaf blades linear to narrowly elliptic or narrowly lanceolate, 1.5–6 cm; peduncles 0.15–1 cm; flowers erect; pedicels 5–13 mm; corolla lobes erect, mostly concealing corona, 7–10 mm, glabrous abax­ially; anthers green; corona segments yellowish green to green, 1.5–2.5 mm, appendage absent; fruiting pedicels straight, follicles 0.3–0.5 cm wide, puberulent with curved trichomes.
A. pedicellata
131. Corona appendages falcate or acicular, well exserted.
→ 135
135. Corona segment apices truncate.
→ 136
136. Petioles 10–25 mm; corollas white with red-violet at base of lobes; anthers brown, 1.5–2 mm; seeds 5–7 × 3–5 mm.
A. variegata
136. Petioles 0–15 mm; corollas green, sometimes tinged pink, red, or purple; anthers green, 2.5–4 mm; seeds 6.5–13 × 4–10 mm.
→ 137
137. Petioles 5–15 mm; leaf blades membranous, base cuneate; corona segments tubular, appendage arching above style apex; ne United States to n Alabama, n Georgia, w North Carolina, w South Carolina.
A. exaltata
137. Petioles 0–9 mm; leaf blades chartaceous, coriaceous, or succulent, base obtuse to cordate; corona segments conduplicate, appendage sharply inflexed over or towards style apex; w United States or s Alabama, Florida, s Georgia, e North Carolina, e South Carolina, and e Texas.
→ 138
138. Leaf blade apices attenuate to acuminate, margins erose; umbels terminal and extra-axillary; peduncles 2–10 cm; pedicels 20–45 mm; corolla lobes tomentose abaxially at tips; anthers 2.5–3 mm; corona segment appendages glabrous; seeds 8–13 × 5–10 mm; n Arizona, s California, s Nevada, sw Utah.
A. erosa
138. Leaf blade apices acute to truncate, sometimes emargin­ate, margins entire or crisped; umbels only extra-axillary; peduncles 0–2.5 cm; pedicels 12–35 mm; corolla lobes gla­brous abaxially; anthers 3–4 mm; corona seg­ment appendages papillose; seeds 6.5–8 × 4.5–6 mm; se United States or c United States to n Arizona, s Utah.
→ 139
139. Petioles 2–9 mm; leaf blades 1–5 cm wide; peduncles 0–0.3 cm; pedicels 12–19 mm; corona segments green with cream apex, often tinged pink or purple; follicles fusiform to narrowly lance-ovoid, 9–18 × 1–1.5 cm; se United States and e Texas.
A. tomentosa
139. Petioles 0–4 mm; leaf blades 3–14 cm wide; peduncles 0–2.5 cm; ped­icels 15–35 mm; corona segments cream, sometimes yellow dorsally; follicles ovoid, 6.5–9.5 × 2–3 cm; c United States.
A. latifolia
135. Corona segment apices acute to obtuse.
→ 140
140. Stems often branched, at least in inflorescence; interpetiolar ridges present; corona segment appendages arching above style apex; fruiting pedicels straight.
→ 141
141. Corollas red, sometimes yellow in throat (may be uniformly yellow or orange in cultivars), lobes 6–9 mm; gynostegial column 2–2.5 mm; corona segments yellow to orange, 3.5–4 mm, appendage falcate; follicles glabrous; seeds 6–7 × 4–5 mm; California, Florida, Louisiana, Texas.
A. curassavica
141. Corollas pink to white, lobes 5–6 mm; gynostegial column 1.2–1.5 mm; corona segments pink to white, 2–2.5 mm, appendage acicular; follicles sparsely puberulent with curved trichomes to pilose or pilosulous; seeds 8–9 × 5–6 mm; widespread in United States and Canada.
A. incarnata
140. Stems unbranched (rarely branched in A. syriaca, branched only in the inflorescence in A. hallii, A. purpurascens); interpetiolar ridges absent; corona segment appendages sharply inflexed over style apex (sometimes ascending in A. ovalifolia); fruiting ped­icels upcurved.
→ 142
142. Stems 30–70 cm; flowers 5–29 per umbel; gynostegial column 0.2–1 mm; follicles 0.7–2 cm wide; seeds 5–7 mm.
→ 143
143. Petioles 10–20 mm; corollas pale pink to red or green, tinged pink or red, lobes 7–8 mm, glabrous abaxially; anthers brown, 2–2.5 mm; corona seg­ments cream with red, pink, or purple dorsal stripe, 5–6.5 mm; follicles 8–12 cm; Rocky Mountains and associated alluvial plains.
A. hallii
143. Petioles 3–10 mm; corollas cream to yellowish, lobes 5–7 mm, pilosulous abaxially at apices; anthers green, 1.5–2 mm; corona segments cream to yellowish, 3–4 mm; follicles 5–8 cm; s Canada (Alberta to Ontario), n United States (Montana and Wyoming e to Illinois and Michigan).
A. ovalifolia
142. Stems 50–200 cm; flowers 17–113 per umbel; gynostegial column 1–1.5 mm; follicles 1.5–4 cm wide; seeds 7–8 mm.
→ 144
144. Adaxial leaf blades sparsely pilosulous; umbels terminal and extra-axillary; flowers erect to spreading; corollas reddish purple, lobes glabrous abaxially; anthers brown; corona segments reddish purple, stipitate, conduplicate, apex acute, 5–6 mm; follicles 10–16 × 1.5–2.5 cm, smooth, puberulent with curved trichomes.
A. purpurascens
144. Adaxial leaf blades tomentose to glabrate; umbels only extra-axillary; flowers erect to pendent; corollas dark to pale pink or green, lobes pilose abaxially; anthers green; corona segments reddish purple to cream, sessile, tubular, apex obtuse, flared, 4–5 mm; follicles 7–12 × 2–4 cm, muricate (sometimes smooth), tomentose.
A. syriaca
Source FNA vol. 14. FNA vol. 14. Author: Mark Fishbein.
Parent taxa Apocynaceae > Asclepias Apocynaceae
Sibling taxa
A. albicans, A. amplexicaulis, A. angustifolia, A. arenaria, A. asperula, A. brachystephana, A. californica, A. cinerea, A. connivens, A. cordifolia, A. cryptoceras, A. curassavica, A. curtissii, A. cutleri, A. eastwoodiana, A. elata, A. emoryi, A. engelmanniana, A. eriocarpa, A. erosa, A. exaltata, A. fascicularis, A. feayi, A. hallii, A. hirtella, A. humistrata, A. hypoleuca, A. incarnata, A. involucrata, A. labriformis, A. lanceolata, A. lanuginosa, A. latifolia, A. lemmonii, A. linaria, A. linearis, A. longifolia, A. macrosperma, A. macrotis, A. meadii, A. michauxii, A. nummularia, A. nyctaginifolia, A. obovata, A. oenotheroides, A. ovalifolia, A. pedicellata, A. perennis, A. prostrata, A. pumila, A. purpurascens, A. quadrifolia, A. quinquedentata, A. rubra, A. rusbyi, A. ruthiae, A. sanjuanensis, A. scaposa, A. solanoana, A. speciosa, A. sperryi, A. stenophylla, A. subulata, A. subverticillata, A. sullivantii, A. syriaca, A. texana, A. tomentosa, A. tuberosa, A. uncialis, A. variegata, A. verticillata, A. vestita, A. viridis, A. viridula, A. welshii
Subordinate taxa
A. albicans, A. amplexicaulis, A. angustifolia, A. arenaria, A. asperula, A. brachystephana, A. californica, A. cinerea, A. connivens, A. cordifolia, A. cryptoceras, A. curassavica, A. curtissii, A. cutleri, A. eastwoodiana, A. elata, A. emoryi, A. engelmanniana, A. eriocarpa, A. erosa, A. exaltata, A. fascicularis, A. feayi, A. hallii, A. hirtella, A. humistrata, A. hypoleuca, A. incarnata, A. involucrata, A. labriformis, A. lanceolata, A. lanuginosa, A. latifolia, A. lemmonii, A. linaria, A. linearis, A. longifolia, A. macrosperma, A. macrotis, A. meadii, A. michauxii, A. nummularia, A. nyctaginifolia, A. obovata, A. oenotheroides, A. ovalifolia, A. pedicellata, A. perennis, A. prostrata, A. pumila, A. purpurascens, A. quadrifolia, A. quinquedentata, A. rubra, A. rusbyi, A. ruthiae, A. sanjuanensis, A. scaposa, A. solanoana, A. speciosa, A. sperryi, A. stenophylla, A. subulata, A. subverticillata, A. sullivantii, A. syriaca, A. texana, A. tomentosa, A. tuberosa, A. uncialis, A. variegata, A. verticillata, A. vestita, A. viridiflora, A. viridis, A. viridula, A. welshii
Synonyms Acerates ivesii, A. viridiflora var. lanceolata, A. viridiflora var. linearis Acerates, Anantherix, Asclepiodella, Asclepiodora, Biventraria, Oxypteryx, Podostemma, Podostigma, Solanoa
Name authority Rafinesque: Med. Repos., hexade 2, 5: 360. (1808) Linnaeus: Sp. Pl. 1: 214. (1753): Gen. Pl. ed. 5, 102. (1754)
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