Kansas Wildflowers and Grasses - Sullivant milkweed

SULLIVANT MILKWEED

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Asclepias sullivantii Engelm. ex A. Gray

Riley County, Kansas

Perennial

Height: 2-4 feet

Family: Apocynaceae - Dogbane Family

Flowering Period: June, July, August

Also Called:

Smooth milkweed.

Stems:

Erect, stout, simple or sometimes slightly branched above, glabrous, waxy.

Leaves:

Opposite, simple, mostly sessile, ascending to spreading, thick, broadly ovate to oblong, 2.5 to 6 inches long, 1 to 3.5 wide, glabrous; margins entire; tips blunt to rounded, usually bearing a short point.

Inflorescences:

Umbels, 1 to several, in upper leaf axils, 15-40-flowered, stalks .5 to 3 inches long.

Flowers:

5-parted, .6 to .8 inch tall; stalks slender, 1 to 1.5 inch long; sepals 5, lanceolate to ovate, green to purplish or pinkish, glabrous; corolla lobes 5, pinkish rose to rose-purple, glabrous, bent abruptly downward; hoods somewhat fleshy, ovate-oblong, attached near bases, spreading; horns sickle-shaped, in-curved, fused to lower half of hoods.

Fruits:

Pods, spindle-shaped, 3 to 4 inches long, about 1 inch wide, finely hairy or glabrous, erect or ascending on downward-curved stalks; seeds many, compressed, tufted with silky white hairs at tips.

Habitat:

Moist lowland prairies and roadsides, most abundant on limestone soils.

Distribution:

East half of Kansas.

Comments:

Smooth milkweed tends to occur in colonies. It is named after William Sterling Sullivant, 1803-1873, an authority on mosses. Formerly treated as Asclepiadaceae - Milkweed Family.

The flowers are showier than those of common milkweed (Asclepias syriaca L.), which has pubescence on the stem and leaves.

Sullivant milkweed