Asclepias texana
Asclepias tomentosa
Texas milkweed
tuba milkweed, velvetleaf milkweed
1–numerous, erect, sparsely to moderately branched in upper half, 25–90 cm, puberulent with curved trichomes in a line, not glaucous, rhizomes absent.
solitary (rarely 2), erect, unbranched (rarely branched), 25–150 cm, densely puberulent with curved trichomes, not glaucous, rhizomes absent.
opposite, petiolate, with 1 or 2 stipular colleters on each side of petiole on a ciliate interpetiolar ridge;
petiole 5–20 mm, puberulent with curved trichomes;
blade ovate to lanceolate or elliptic, 2–7 × 0.5–3 cm, chartaceous, base cuneate to obtuse, margins entire, apex acute to acuminate, venation eucamptodromous, surfaces puberulent with curved trichomes on veins abaxially, sparsely puberulent with curved trichomes on veins to glabrate adaxially, margins ciliate, laminar colleters absent.
opposite, petiolate, with 1 stipular colleter on each side of petiole;
petiole 2–9 mm, densely puberulent with curved trichomes;
blade lanceolate or ovate to oval or oblong or elliptic to oblanceolate or obovate, 3.5–10 × 1–5 cm, chartaceous, base obtuse to subcordate, margins crisped, apex acute or obtuse to truncate or emarginate, sometimes mucronate, venation eucamptodromous to brochidodromous, surfaces puberulent with curved trichomes to tomentulose, margins ciliate, 4–8 laminar colleters.
extra-axillary at upper nodes, some appearing terminal, pedunculate, 14–31-flowered;
peduncle 0.9–3 cm, puberulent with curved trichomes in a line, with 1 caducous bract at the base of each pedicel.
extra-axillary, sessile or pedunculate, 5–37-flowered;
peduncle 0–0.3 cm, densely puberulent with curved trichomes to tomentulose, with 1 caducous bract at the base of each pedicel.
7–14 mm, puberulent with curved trichomes in a line.
12–19 mm, densely pilose to tomentulose.
erect;
calyx lobes narrowly lanceolate, 1.5–2 mm, apex acute, puberulent with curved trichomes;
corolla white, sometimes tinged green, lobes reflexed with spreading tips, elliptic, 3.5–5 mm, apex acute to obtuse, glabrous abaxially, minutely papillose at base adaxially;
gynostegial column 1–1.5 mm;
fused anthers brown, columnar, 1.5–2 mm, wings narrowly right-triangular, closed, apical appendages deltoid;
corona segments white, sometimes tinged pink, stipitate, cupulate, dorsally rounded, 2–3 mm, equaling to slightly exceeding style apex, apex obtuse, glabrous, internal appendage acicular, exserted, arching over style apex, glabrous;
style apex shallowly depressed, white.
erect;
calyx lobes lanceolate, 3–4 mm, apex acute, pilose;
corollas green, often tinged reddish or purplish, lobes reflexed with spreading tips, oval, 7–9 mm, apex acute, glabrous;
gynostegial column 0.5–1 mm;
fused anthers green, obconic, 3–4 mm, wings broadly right-triangular, closed, apical appendages broadly oval;
corona segments green with cream apex, often tinged pink or purple, stipitate, conduplicate, dorsally flattened, 3–4 mm, exceeded by style apex, apex truncate, glabrous, internal appendage falcate, exserted, sharply inflexed towards style apex, papillose;
style apex shallowly depressed, green, fading pink or red.
ovate, 6–7 × 4–5 mm, margin winged, faces smooth or sparsely papillose;
coma 2–3 cm.
ovate, 6.5–8 × 4.5–6 mm, margin winged, remotely erose, faces minutely and sparsely papillose and rugulose;
coma 3–3.5 cm.
erect on straight pedicels, narrowly fusiform, 9–13 × 0.5–1 cm, apex long-acuminate to attenuate, smooth, glabrous.
erect on upcurved pedicels, fusiform to narrowly lance-ovoid, 9–18 × 1–1.5 cm, apex long-acuminate, smooth, puberulent with curved trichomes to pilosulous or tomentulose.
Asclepias texana
Asclepias tomentosa
In the flora area, Asclepias texana has a disjunct distribution on the Edwards Plateau and in the mountains of the Big Bend region. Although commonly occurring in canyons and riparian areas, A. texana is quite drought tolerant in cultivation. The tidy, bushy habit, long flowering stems topped by bright white spherical umbels, and rapid growth from seed make this a suitable candidate for horticultural use. It is known to be hardy to at least USDA Zone 7.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
Asclepias tomentosa is restricted largely to coastal and inland sandhills. As described by B. A. Sorrie (2016), it exhibits a disjunct distribution, with gaps of unoccupied, but suitable, habitat in eastern Georgia and from the western Florida Panhandle to Louisiana. Sorrie reports a specimen from Alabama, but this cannot be found. When not in flower, A. tomentosa can be confused with A. curtissii in peninsular Florida, where they sometimes co-occur in close proximity, and with A. obovata on the Gulf Coastal Plain. It can be distinguished from A. curtissii by the usually larger and more densely vestitured leaf blades. Both species may have purple stems. Asclepias obovata can be distinguished from A. tomentosa by the hirtellous to velutinous vestiture of the herbage. Outside of Florida, populations of A. tomentosa are few, but it has not been considered to be of conservation concern; evaluation of its status in Texas and Georgia (known only from Coffee County) may be warranted.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
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