Asclepias viridiflora
Asclepias scaposa
asclépiade à fleurs vertes, green antelopehorn milkweed, green comet milkweed, green milkweed
bear mountain milkweed
solitary, erect to ascending, unbranched (rarely), (10–)20–125 cm, puberulent with curved trichomes, not glaucous, rhizomes absent.
1–5+, erect, unbranched (rarely at base), 15–20 cm, pilosulous, not glaucous, rhizomes absent.
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.
opposite, sessile or petiolate, with 1 stipular colleter on each side of petiole;
petiole 0–6 mm, pilosulous to glabrate;
blade oval to elliptic, 6–8 × 1.5–2.5 cm, membranous, base cuneate, margins crisped, apex obtuse to acute, venation eucamptodromous, surfaces sparsely hirtellous, margins ciliate, laminar colleters absent.
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.
terminal, solitary, pedunculate, 15–30-flowered;
peduncle 7–17 cm, pilose, bracts absent or few.
7–13 mm, pilosulous.
15–20 mm, pilose.
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.
erect to pendent;
calyx lobes narrowly lanceolate, 2–2.5 mm, apex acute, pilose;
corolla green with purplish tinge (reddish purple), lobes reflexed, elliptic, 4–5 mm, apex acute, glabrous;
gynostegial column 0.5–1 mm;
fused anthers brown, cylindric, 1.5–2 mm, wings curved, wider at base, apical appendages ovate;
corona segments cream, sometimes yellow- or red-tinged or yellow or red at base, sessile, tubular, 2–3 mm, exceeding style apex, base saccate, apex truncate, dentate, glabrous, internal appendage falcate, exserted, arching above style apex, glabrous;
style apex shallowly depressed, green or cream.
ovate, 7–8 × 4–5 mm, margin winged, faces minutely rugulose;
coma 2.5–3 cm.
not seen.
erect on upcurved pedicels, fusiform to lance-ovoid, 6–10 × 1.5–2 cm, apex acuminate to attenuate, smooth, pilosulous.
erect on upcurved pedicels, fusiform, 5–6 × 1–1.5 cm, apex long-acuminate, smooth, pilosulous.
= 22.
Asclepias viridiflora
Asclepias scaposa
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.)
The long-pedunculate, terminal inflorescence combined with short stature is distinctive in Asclepias scaposa. Although the locality of one of the syntypes was attributed to New Mexico by E. L. Greene, that is the only report for that state. Both syntypes were collected by Charles Wright for the United States-Mexico boundary survey, but neither of his labels indicates that they were collected in New Mexico. It is very likely that both collections were made in Texas or northeastern Mexico, and New Mexico is excluded from the distribution here. The common name Bear Mountain milkweed may refer to a ridge in the northwestern portion of the Davis Mountains, although no collections are known from this area. The few collections and observations that have been made in Texas are from scattered locations in Brewster, Crockett, Pecos, Presidio, Reeves, and Terrell counties, and conservation status in the United States merits assessment. In Mexico, A. scaposa also has been rarely collected, except for a local area in Nuevo León (Municipio de Galeana).
(Discussion copyrighted by Flora of North America; reprinted with permission.)
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