Asclepias obovata |
Asclepias fascicularis |
|
---|---|---|
pineland milkweed |
Mexican whorled milkweed, narrow-leaf milkweed, narrow-leaf or Mexican or Mexican whorled milkweed |
|
Habit | Herbs. | Herbs. |
Stems | 1 (rarely more), erect to spreading, unbranched, 40–70(–200) cm, densely hirtellous to velutinous, not glaucous, rhizomes absent. |
few–numerous, erect, sparsely to moderately branched, 50–150 cm, glabrous, not glaucous, rhizomes absent. |
Leaves | opposite, petiolate, with 1 or 2 stipular colleters on each side of petiole; petiole 1–4 mm, densely hirtellous to velutinous; blade oblong or elliptic to obovate or ovate, 4–9 × 1–3.5 cm, subcoriaceous, base rounded or truncate to cordate, margins sometimes crisped, apex acute to truncate, sometimes emarginate, often mucronate, venation brochidodromous, surfaces densely hirtellous to velutinous abaxially, hirtellous adaxially, margins ciliate, 8–12 laminar colleters. |
3–5-whorled, sessile or petiolate, with 1–3 stipular colleters on each side of petiole on a ciliate interpetiolar ridge; petiole 0–4 mm, margins puberulent with curved trichomes; blade linear to linear-lanceolate or narrowly elliptic, often somewhat conduplicate, 4.5–13 × 0.2–1.8 cm, membranous, base cuneate, margins entire, apex acute or attenuate to obtuse, mucronate, venation obscure to faintly eucamptodromous, surfaces glabrous, margins eciliate, laminar colleters absent. |
Inflorescences | extra-axillary, sometimes also appearing terminal, sessile or pedunculate, 7–31-flowered; peduncle 0–0.5 cm, densely hirtellous to velutinous, with 1 caducous bract at the base of each pedicel. |
terminal and extra-axillary at upper nodes, sometimes branched, pedunculate, 10–37-flowered; peduncle 0.4–5.5 cm, puberulent with curved trichomes in a line to glabrate, with 1 caducous bract at the base of each pedicel. |
Pedicels | 10–12 mm, densely hirtellous to velutinous. |
9–14 mm, puberulent with curved trichomes to pilosulous. |
Flowers | erect to pendent; calyx lobes elliptic, 5–6 mm, apex acute, densely hirtellous; corolla green, sometimes tinged reddish or bronze, lobes reflexed, sometimes with spreading tips, elliptic, 7–9 mm, apex acute, glabrous abaxially, minutely papillose at base adaxially; gynostegial column 1–1.5 mm; fused anthers green, obconic, 2.5–4 mm, wings right-triangular, open at base, apical appendages broadly ovate; corona segments bronze to yellow, often tinged red, sometimes apically cream or pale, stipitate, tubular, somewhat flattened laterally, flared at base, 5–8 mm, greatly exceeding style apex, apex rounded, flared, glabrous, internal appendage falcate, exserted, sharply incurved over style apex, glabrous; style apex shallowly depressed, green. |
erect; calyx lobes lanceolate, 1.5–2 mm, apex acute, puberulent with curved trichomes to pilosulous; corolla pale to dark pink, rarely pale green with a pink tinge, lobes reflexed with spreading tips, oval, 3–5 mm, apex acute, glabrous abaxially, minutely papillose at base adaxially; gynostegial column 1–1.5 mm; fused anthers green, cylindric, 1.5–2 mm, wings narrowly right-triangular, closed, apical appendages deltoid; corona segments cream, often tinged or striped pink, stipitate, cupulate, dorsally somewhat flattened, 1.5–2 mm, exceeded by style apex, apex obtuse, glabrous, internal appendage acicular, exserted, arching towards style apex, glabrous; style apex shallowly depressed, cream. |
Seeds | broadly ovate, 8–9 × 6–7 mm, margin winged, faces smooth; coma 2–5 cm. |
ovate, 6–7 × 4–5 mm, margin winged, faces minutely rugulose; coma 2.5–3 cm. |
Follicles | erect on upcurved pedicels, narrowly to broadly fusiform, 7.5–12.5 × 1.5–2.5 cm, apex acuminate, smooth, densely hirtellous to velutinous. |
erect on straight pedicels, fusiform, 6–9 × 0.5–1 cm, apex attenuate, smooth, glabrous. |
2n | = 22. |
|
Asclepias obovata |
Asclepias fascicularis |
|
Phenology | Flowering May–Sep; fruiting Jul–Oct. | Flowering Apr–Oct; fruiting (Jun–)Jul–Nov. |
Habitat | Hills, slopes, flats, ridges, sandhills, ditches, seeps, bogs, sandstone, sandy, rocky, silty, and clay soils, pine flatwoods, pine savannas, pine, pine-oak, and bottomland hardwood forests, prairies, often following fires. | Valleys, slopes, hills, streamsides, ditches, seeps, hot springs, wet depressions, arroyos, vernal pools, basalt, granite, limestone, clay, sandy, and silty soils, native, non-native, and shrubby grasslands, oak, pine-oak, juniper, pinyon-juniper, and riparian woodlands, chaparral, coastal sage scrub, pine and mixed-conifer forests, sometimes following fires. |
Elevation | 0–200 m. (0–700 ft.) | 0–2300 m. (0–7500 ft.) |
Distribution |
AL; AR; FL; GA; LA; MS; OK; SC; TX
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CA; ID; NV; OR; WA; Mexico (Baja California)
|
Discussion | Asclepias obovata is a common milkweed of seasonally wet, sandy soils in pine woodlands of the Gulf Coastal Plain and (rarely) the southern Atlantic Coastal Plain. It is rare and considered to be of conservation concern in Arkansas. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Asclepias mexicana Decaisne was misapplied to A. fascicularis in the past; this is the legitimate name of a related species endemic to southern and eastern Mexico. The common name Mexican (whorled) milkweed stems from this past confusion. Compared to its close relatives A. angustifolia, A. linearis, A. pumila, A. subverticillata, and A. verticillata, the leaves of A. fascicularis are not particularly narrow (despite the implication of another common name). However, very narrow leaves are found in A. fascicularis when it is growing at relatively dry sites, especially at the eastern limit of its range in southeastern Idaho. Such specimens (for example, Mumford 272 [MO], Atwood 28495 [NY]) have been attributed in the past to A. subverticillata in error. Asclepias fascicularis is completely allopatric with its Incarnatae clade relatives (species 7–16). Like these species, it is easily cultivated, and its seeds are widely available. In Washington, the range of A. fascicularis is restricted largely to the valleys of the Columbia and Spokane rivers and in Idaho to the Snake and Weiser rivers. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Source | FNA vol. 14. | FNA vol. 14. |
Parent taxa | Apocynaceae > Asclepias | Apocynaceae > Asclepias |
Sibling taxa | ||
Name authority | Elliott: Sketch Bot. S. Carolina 1: 321. (1817) | Decaisne in A. P. de Candolle and A. L. P. P. de Candolle: Prodr. 8: 569. (1844) |
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