Asclepias brachystephana
Asclepias quinquedentata
bract milkweed, short-crowned milkweed, shortcrown milkweed
slim-pod milkweed
4–25, erect, unbranched or branched near base, 20–40 cm, tomentulose, not glaucous, rhizomes absent.
1–5, erect to ascending, sometimes decumbent at base, unbranched or branched near base, 10–60 cm, sparsely puberulent with curved trichomes to glabrate, not glaucous, rhizomes absent.
opposite to subopposite, petiolate, with 1 or 2 stipular colleters on each side of petiole;
petiole 2–8 mm, tomentulose;
blade linear-lanceolate, 5–15 × 0.3–1.3 cm, chartaceous, base cuneate to rounded, margins often obscurely crisped, apex acute, mucronate, venation brochidodromous, surfaces tomentulose to glabrate, midvein puberulent with curved trichomes, margins minutely ciliate, laminar colleters absent.
opposite, sessile or petiolate, with 1 or 2 stipular colleters on each side of petiole;
petiole 0–1 mm, puberulent with curved trichomes to glabrate;
blade linear, 6–14 × 0.2–0.6 cm, membranous, base cuneate, margins entire, apex acute, mucronate, venation obscure to faintly eucamptodromous, surfaces sparsely puberulent with curved trichomes on midvein to glabrate, margins ciliate, 0–2 laminar colleters.
extra-axillary, pedunculate, 4–15-flowered;
peduncle 0.2–1.5 cm, tomentose, with 1 caducous bract at the base of each pedicel.
extra-axillary, the uppermost appearing terminal, pedunculate, 4–10-flowered (appearing greater because umbels are in close proximity);
peduncle 1.1–2.7 cm, sparsely puberulent with curved trichomes, with 1 bract at the base of each pedicel.
9–15 mm, tomentose.
14–21 mm, puberulent with curved trichomes.
erect;
calyx lobes ovate-lanceolate, 2–3 mm, apex acute, tomentulose;
corolla red-violet, sometimes green with red tinge, lobes reflexed, ovate, 4–6 mm, apex acute, minutely pilosulous;
gynostegium subsessile;
fused anthers brown, cylindric, 2–2.5 mm, wings right-triangular, closed, apical appendages ovate;
corona segments red-violet to pink basally, white apically, sessile, tubular, 1.5–2 mm, greatly exceeded by style apex, apex truncate, oblique, with a proximal tooth on each side, glabrous, internal appendage lingulate, slightly exserted, sharply inflexed towards gynostegium, glabrous;
style apex shallowly depressed, red-violet.
pendent to spreading;
calyx lobes lanceolate, 2.5–3.5 mm, apex acute, strigulose to pilosulous;
corolla green, sometimes tinged red, lobes reflexed, exposing corona, oval, 4–6 mm, apex acute, pilose abaxially, glabrous adaxially;
gynostegial column 0.5 mm;
fused anthers tan to brown, cylindric, 1.5–2 mm, wings narrowly right-triangular, slightly open at base, apical appendages ovate;
corona segments red or pink to red-violet or purple at base, white at apex, shiny, sessile, conduplicate, dorsally rounded, 3–4 mm, equaling to slightly exceeding style apex, apex truncate with a proximal tooth on each side, glabrous, internal appendage a crest, barely exserted from cavity;
style apex shallowly depressed, white to greenish.
oval to ovate, 6–7 × 4–6 mm, margin winged, faces papillate-tomentulose with dendritic scales;
coma 2–2.5 cm.
ovate, 4–5 × 3–4 mm, margin winged, faces smooth;
coma 2–2.5 cm.
erect on upcurved pedicels, lance-ovoid, 5–7 × 1.2–1.8 cm, apex acuminate, shallowly ribbed, conspicuously striate, tomentulose.
erect on upcurved pedicels, fusiform, 8.5–16 × 0.5–1 cm, apex long-attenuate, smooth, faintly striate, pilosulous to glabrate.
Asclepias brachystephana
Asclepias quinquedentata
Asclepias brachystephana is a blue-gray, bushy herb with ascending foliage, few-flowered umbels of small, red and white flowers, and conspicuously striped follicles. It is unlike any other milkweed. Nonetheless, herbarium specimens are commonly confused with those of A. asperula because the herbage of A. brachystephana turns green on drying, and the leaves of A. asperula subsp. asperula are often of similar size and shape. However, leaf arrangement in A. asperula is alternate rather than opposite. The flowers of A. brachystephana are remarkably similar to, and convergent with, those of A. cutleri, A. eastwoodiana, A. ruthiae, A. sanjuanensis, and A. uncialis (M. Fishbein et al. 2011). In Arizona, A. brachystephana is restricted to the portion of the southeastern corner of the state with Chihuahuan floristic affinities, in Cochise, Graham, Pima, and Santa Cruz counties.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
Although it is widely distributed, Asclepias quinquedentata is rarely encountered. The plant is cryptic, even in flower, because of the slender, few-leaved habit and nodding inflorescences. Nonetheless, it appears to truly be rare, at least in the United States. It is considered to be of conservation concern in Arizona, and its status in New Mexico requires evaluation. It has been reported from Texas, based on the presumed type locality. However, M. Fishbein et al. (2008) concluded that the type collection most likely was made in Arizona. The population in the Valle de México has been segregated as A. rzedowskii based on a subtle variant of the corona; it is here considered a synonym (Fishbein et al.).
(Discussion copyrighted by Flora of North America; reprinted with permission.)
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