Flora of North America species comparison

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Asclepias cordifolia

Asclepias eastwoodiana
Asclepias cordifolia

heart-leaf milkweed, purple milkweed

Eastwood's milkweed
Habit Herbs. Herbs.
Stems

1–20, ascending to spreading, unbranched, 25–100 cm, glabrous, glaucous, rhizomes absent.

1–6, ascending to decumbent, unbranched or branched near base, 6–30 cm, puberulent with curved trichomes, not glaucous, rhizomatous.
Leaves

opposite, sessile, stipular colleters absent;

blade ovate to lanceolate, 3.5–11 × 1.8–8 cm, chartaceous, base cordate, clasping, margins entire, apex acute, mucronate, venation brochidodromous to eucamptodromous, surfaces glabrous, glaucous, margins minutely ciliate, laminar colleters absent.

proximally opposite, distally alternate, petiolate, with 0 or 1 stipular colleter on either side of petiole;

petiole 2–10 mm, puberulent with curved trichomes;

blade narrowly lanceolate to ovate, 2–4.5 × 0.6–3 cm, chartaceous, base cuneate to obtuse, margins entire, apex acute, mucronate, venation eucamptodromous, surfaces strigulose or pilosulous on midvein to glabrate, margins densely ciliate, laminar colleters absent.
Inflorescences

terminal, branched, sometimes also extra-axillary at upper nodes, pedunculate, 5–20-flowered;

peduncle 0.3–6.5 cm, apically sparsely pilose to glabrate, with few bracts.

terminal and extra-axillary at upper nodes, sessile or pedunculate, 2–25-flowered;

peduncle 0–4 cm, puberulent with curved trichomes to glabrate, bracts few.
Pedicels

16–37 mm, sparsely pilose.

10–28 mm, pilosulous to puberulent with curved trichomes.
Flowers

erect to pendent;

calyx lobes elliptic to lanceolate, 3–5 mm, apex acute, pilose;

corolla red-violet, lobes reflexed with spreading tips, oval, 6–7 mm, apex acute, glabrous;

gynostegial column 1–1.5 mm;

fused anthers brown, cylindric, 1.5–2 mm, wings right-triangular, open at tip, apical appendages deltoid;

corona segments white, tinged pink to red-violet at base, sessile, tubular, 2–3 mm, exceeded by style apex, base saccate, apex truncate, oblique, glabrous, internal appendage absent;

style apex shallowly depressed, pink to red-violet.

erect;

calyx lobes elliptic to lanceolate, 2–2.5 mm, apex acute, puberulent with curved trichomes to pilosulous;

corolla red-violet, faintly striate, lobes reflexed with spreading tips, oval, 4–5 mm, apex acute, glabrous;

gynostegial column 0.2–0.5 mm;

fused anthers brown, cylindric, 1.5–2 mm, wings right-triangular, apical appendages ovate;

corona segments red-violet dorsally, white proximally, sessile, cupulate, 1.5–2 mm, slightly exceeded by style apex, apex truncate with a proximal tooth on each side, glabrous, internal appendage conical, barely exserted from cavity, glabrous;

style apex shallowly depressed, pink to red-violet.
Seeds

ovate, 8–9 × 5–7 mm, margin not winged, faces reticulate-rugulose;

coma 3–3.5 cm.

not seen.
Follicles

erect on upcurved pedicels, lance-ovoid, 7.5–10.5 × 1.5–1.8 cm, apex long-acuminate, smooth, glabrous, glaucous.

spreading to pendulous on spreading pedicels, lance-ovoid, 3.5–6 × 0.5–1 cm, apex acuminate, smooth, faintly striate, strigose.
2n

= 22.

Asclepias cordifolia

Asclepias eastwoodiana
Phenology Flowering Mar–Jul(–Aug); fruiting Jun–Sep. Flowering May–Jun; fruiting Jun.
Habitat Hill­sides, canyons, ridge tops, streamsides, seeps, basalt, serpentine, gabbro, granite, shale, limestone, talus slopes, gravel, alluvium, oak woodlands, mixed ever­green, douglas-fir, pine, pine-oak, and riparian forests, chaparral, timberline meadows, grasslands. Valleys, depres­sions, flats, slopes, arroyos, dunes, granite, gravel, sandy, calcareous, and clay soils, shrubby grasslands, desert scrub, pinyon-juniper woodlands.
Elevation 50–2200(–2800) m. [160–7200(–9200) ft.] 1400–2200 m. [4600–7200 ft.]
Distribution
from FNA
CA; NV; OR
[WildflowerSearch map]
[BONAP county map]
from FNA
NV
[BONAP county map]
Discussion

Fresh leaves and stems of Asclepias cordifolia are often slightly or strongly colored bluish, grayish, or purplish. This is one of the few American species of Asclepias with cavitate corona segments that lack adaxial appendages. Such species were segregated along with diverse African species in Gomphocarpus R. Brown, a polyphyletic segregate (M. Fishbein et al. 2011; D. Chuba et al. 2017). Asclepias cordifolia is a distinctive species unlike any other within its range. It is phylogenetically and geographically isolated, although not highly derived morphologically. In Nevada, A. cordifolia is restricted to the Sierra Nevada, in Carson City, Douglas, and Washoe counties. Its range extends to northern California and southwestern Oregon.

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

Asclepias eastwoodiana and the next three species (A. ruthiae, A. sanjuanensis, A. uncialis) form a complex of largely allopatric entities that have sometimes been united in a single species, for which the name A. uncialis holds priority (for example, E. Sundell 1994). However, each entity shows genetic, chemical, and subtle morphological distinctions, supporting recognition at the specific rank (M. B. Sady and J. N. Seibert 1991; J. P. Riser et al. 2019). Asclepias eastwoodiana is distinguished from the others by the differences in leaf shape, vestiture, and corona morphology indicated in the key. With A. ruthiae it shares a spreading to pendulous fruit that differs from the typically erect fruits of A. sanjuanensis and A. uncialis. Asclepias eastwoodiana is endemic to valleys in central Nevada (Esmeralda, Lander, Lincoln, Mineral, and Nye counties), where it is considered to be a species of conservation concern, potentially threatened by livestock trampling and mining development.

(Discussion copyrighted by Flora of North America; reprinted with permission.)
Source FNA vol. 14. Treatment author: Mark Fishbein. FNA vol. 14. Treatment author: Mark Fishbein.
Parent taxa Apocynaceae > Asclepias Apocynaceae > Asclepias
Sibling taxa
A. albicans, A. amplexicaulis, A. angustifolia, A. arenaria, A. asperula, A. brachystephana, A. californica, A. cinerea, A. connivens, 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
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. 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 cordifolia, Gomphocarpus cordifolius
Name authority (Bentham) Jepson: Fl. W. Calif., 384. (1901) Barneby: Leafl. W. Bot. 4: 210. (1945)
Web links 
Unless otherwise noted, all data comes from the online version of the Flora of North America, who have made most of their content available via a Creative Commons license (CC BY 4.0).



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