tuba milkweed

Scientific name: Asclepias tomentosa

Common names: tuba milkweed, woolly milkweed (also referred to as tomentose milkweed)

Family: Asclepiadaceae

Genus: Asclepias

Note: Asclepias is the milkweed genus; taxonomic treatments sometimes place this group within Apocynaceae as the subfamily Asclepiadoideae, but Asclepias remains the accepted genus for these milkweeds.

A low-growing, often sprawling perennial with stems and leaves densely covered in whitish to grayish hairs (tomentum), giving the plant a felted or woolly appearance. Stems may be erect to decumbent and generally remain relatively low to the ground. Leaves are opposite, leathery to slightly succulent in texture, and lanceolate to elliptic in shape; they are typically hairy on both surfaces. Flowers are produced in small, rounded clusters (umbels or cymes); each flower has the characteristic milkweed structure with five reflexed corolla lobes and a central corona composed of hoods and horns. Flower color is often yellow to orange or cream, sometimes appearing muted by the plant’s dense pubescence. Fruits are paired follicles typical of milkweeds, containing flat seeds with silky hairs (coma) adapted for wind dispersal. Seasonal display: flowering generally occurs during the warm season in its range, with the woolly foliage remaining conspicuous outside bloom.

Typically found in sandy, well-drained sites of the southeastern United States, often on coastal plain habitats such as scrub, sandhills, dunes, pine flatwoods, and open sandy fields. Prefers full sun to partial sun and is adapted to dry, nutrient-poor soils; drought-tolerant tendencies are common. Documented from Alabama, Florida, Georgia, North Carolina, South Carolina and one additional nearby state, reflecting a primarily southeastern coastal plain distribution.

As a milkweed, it exhibits the specialized pollination syndrome of the genus: insect visitors (bees, wasps, butterflies and other floral-foraging insects) can remove and transfer pollinia, effecting pollination. The flowers provide nectar to a variety of pollinators, and the plant’s foliage may serve as a larval food source for milkweed-specialist caterpillars in the region, including monarchs and other danaine butterflies, though use can vary locally. Seeds are wind-dispersed via silky comas.

Like many Asclepias species, A. tomentosa contains a milky sap with biologically active compounds and should be regarded as potentially toxic if ingested; handling with care is advised. No widely documented modern medicinal or food uses are broadly accepted in contemporary botanical literature for this species.

The dense tomentum (woolly hairs) is a notable adaptation that helps reduce water loss, reflect intense sunlight and may deter some herbivores. Milkweeds possess a distinctive pollination mechanism involving pollinia—pollen packaged into discrete masses that attach to insect visitors—an unusual strategy among flowering plants.