Asclepias lanuginosa
Asclepias asperula
asclépiade laineuse, side-cluster milkweed, small-green milkweed, woolly milkweed
Antelope horns, spider milkweed
1 or 2 (rarely more), erect to spreading, unbranched, 7–20 cm, densely hirtellous to pilose, not glaucous, rhizomatous.
1–40, erect to decumbent, unbranched or branched at base, 15–60 cm, puberulent with curved trichomes, not glaucous, rhizomes absent.
opposite or alternate, petiolate, with 1 stipular colleter on each side of petiole;
petiole 1–2 mm, hirtellous;
blade oblong or lanceolate to narrowly lanceolate, 4–8 × 0.5–2.7 cm, chartaceous, base cuneate to rounded or subcordate, margins entire, apex acute to obtuse, venation eucamptodromous to reticulodromous, surfaces hirtellous, margins ciliate, laminar colleters absent.
alternate to subopposite, petiolate, with 1–3 stipular colleters on each side of petiole;
petiole 2–4 mm, puberulent with curved trichomes to pilosulous;
blade lanceolate to linear, 5–17 × 0.4–3.7 cm, chartaceous, base cuneate, margins entire, apex attenuate to acute, mucronate, venation eucamptodromous to brochidodromous, surfaces puberulent with curved trichomes to glabrate, more densely so on veins, margins ciliate, laminar colleters absent.
terminal, usually solitary, pedunculate, 17–50-flowered (rarely more);
peduncle 1–3 cm, densely hirtellous to pilose, with 1 caducous bract at the base of each pedicel.
terminal, sessile or pedunculate, 10–60-flowered;
peduncle 0–22.5 cm, puberulent with curved trichomes, with 1 caducous bract at the base of each pedicel.
9–13 mm, hirtellous to pilose.
16–30 mm, puberulent with curved trichomes to pilose.
erect to spreading;
calyx lobes narrowly lanceolate, 1.5–2 mm, apex acute, hirtellous;
corolla greenish cream, sometimes purple-tinged, lobes reflexed, oblong, 3–5 mm, apex acute, glabrous;
gynostegial column 0–0.2 mm;
fused anthers green, broadly cylindric, 1.5–2 mm, wings triangular, widest below middle, closed, apical appendages ovate;
corona segments cream to greenish cream, sessile, chute-shaped, margins incurved, appressed to column, 2–3.5 mm, exceeded by style apex, base saccate, apex rounded, glabrous, internal appendage absent or obscure, glabrous;
style apex shallowly depressed, green to greenish cream.
erect to spreading;
calyx lobes ovate to linear-lanceolate, 3–5 mm, apex acute, pilosulous to puberulent with curved trichomes;
corolla pale green, sometimes tinged red abaxially, campanulate, lobes ascending and exceeding corolla segments, ovate to oval, 7–10 mm, apex acute, puberulent with curved trichomes at apex abaxially, glabrous adaxially;
gynostegium sessile;
fused anthers brown and green, turbinate, 2–2.5 mm, wings trapezoidal, widest above middle, closed, apical appendages ovate, erose;
corona segments reddish purple and white, sessile, clavate-tubular, 4.5–7 mm, slightly exceeded by to equaling style apex, deflexed at base, margins connivent, apex incurved, rounded, upper margin and cavity papillose, internal appendage a low internal crest, papillose;
style apex depressed, green.
ovate, 6–7 × 4–5 mm, faces minutely rugulose;
comose.
ovate, 5–8 × 4–6 mm, margin winged, remotely erose, faces minutely rugulose-papillose, minutely hirtellous;
coma 2.5–4 cm.
erect on upcurved pedicels, fusiform, 8–10 × 0.8–1.5 cm, apex long-acuminate, smooth, hirtellous to pilose.
erect on upcurved pedicels, lance-ovoid, 6–11.5 × 1–2.5 cm, apex short- to long-acuminate, weakly to strongly arcuate, shallowly rugose-ribbed, ribs sometimes muricate, striate, pilosulous.
= 22.
Asclepias lanuginosa
Asclepias asperula
Asclepias lanuginosa is highly cryptic due to its small stature and early flowering. It resembles a short, hirtellous form of A. viridiflora. In addition to the differences in vestiture, A. lanuginosa can be distinguished from that species by the terminal inflorescence and the cream-colored corona segments. Due to severe habitat loss in the tallgrass prairie region, A. lanuginosa has apparently declined and is of conservation concern over much of its range, that is, in Illinois, Iowa, Kansas, North Dakota, South Dakota, and Wisconsin. It is more secure in Nebraska, but an overall re-assessment of the status of this species is warranted. The only report from Montana is from the “Yellowstone expedition,” which may not have been collected in the state. R. E. Woodson Jr. (1954) considered A. lanuginosa Kunth (a later homonym) to be the correct name for a Mexican species, A. otarioides E. Fournier. He soon realized that A. lanuginosa Nuttall has priority, but prior usage and his extensive annotations produced lingering confusion over the correct name of the Mexican species. Torrey’s replacement name for this species, A. nuttalliana, is illegitimate, as it was superfluous on publication.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
Subspecies 2 (2 in the flora).
With terminal umbels of large, green and purple flowers, Asclepias asperula is highly distinctive and in flower can be confused only with its sister species, A. viridis. Distinguishing characteristics and the existence of interspecific hybrids are discussed under A. viridis. Large bees, notably Bombus and Xylocopa, are commonly observed visiting the flowers of A. asperula.
The subspecies of Asclepias asperula are strongly differentiated away from their region of contact, which extends from south of the Texas Panhandle to the extreme tip of the Oklahoma Panhandle. In the region of contact, their distinguishing traits intermix. The common occurrence of intermediates and apparent introgressants argues against elevation of the subspecies to the specific rank. There is a surprising gap in the distribution of the species as a whole on the Llano Estacado in eastern New Mexico and the Texas Panhandle that may contribute to the differentiation of the subspecies.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
1. Corona segments reddish purple with white upper margin, 5–7 mm; follicle ribs inconspicuously muricate at apex or not at all. | subsp. asperula |
1. Corona segments white, dorsally reddish purple, 4.5–6 mm; follicle ribs sparsely to densely muricate for most of the length. | subsp. capricornu |
IL Wildflowers
KS Wildflowers
MN Wildflowers
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