Asclepiadaceae Asclepias macrosperma

Four photos of various closeups of a light colored yellow flower with five petals. Silvery green thin leaves.

Asclepias macrosperma

Family: Asclepiadaceae – Milkweed Family

Asclepias is the only genus from this family represented at Arches National Park.

Perennial herbs from rootstocks with milky latex; stems 3.2” to 20” (8 to 50 cm) above ground

Leaves: usually opposite, infrequently whorled or rarely alternate; simple; wavy margins; has dense hairs; 0.8 to 2.6” (2 to 6.5 cm) long, 0.4” to 1.12” (1 to 2.8 cm) wide

Flowers: typically 5 united pale green to yellow petals (lobed or cleft) folded downward; 5 parted or lobed sepals folded downward; 5 stamens, 2 pistils; plus a corona (an additional structure sitting between the petals and the stamens) that looks like an extra set of petals. The corona consists of 5 hoods; inside the hoods there may be a beak-like structure (horn) pointing toward the center of the flower. Bisexual; flowers are in clusters; petal lobes are 0.2 to 0.24” (5 to 6 mm) long

Pollinators: other Asclepias species are pollinated by bees, moths and butterflies

Fruits: pair of follicles; seeds typically have very silky hairs

Blooms in Arches National Park: April, May, June

Habitat in Arches National Park: desert shrub and pinyon-juniper communities in sandy areas

Location seen: near Petrified Dunes viewpoint (park road mile 6.2)

Other: The genus name, “Asclepias”, refers to “Asklepios”, a Greek physician and an authority on the medicinal use of plants and who according to Greek Myth could bring the dead to life. Hades fearing a loss of employment, convinced his brother Zeus to kill Asklepios with a bolt of lightning. The species name, “macrosperma”, means “large seed” and refers to the pod and the seeds.

Several species of Asclepias are poisonous to humans and livestock. This family is primarily tropical and subtropical.

Last updated: November 27, 2021

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