Curtiss’ milkweed

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Pictured above: Curtiss’ milkweed (Asclepias curtissii) by Emily Bell. Click on terms for botanical definitions. View post as a PDF.

Curtiss’ milkweed (Asclepias curtissii) is a long-lived and somewhat mysterious milkweed endemic to the Florida scrub. The populations of this state-endangered wildflower are widely scattered and sometimes only a single plant will be found within a site. Its population dynamics have been challenging to study because it is very difficult to find when not in bloom and it can remain dormant through more than one season.

Curtiss’ milkweed is deciduous. Its woody stem can grow up to 4 feet long and typically leans, giving it an almost vine-like sprawl. Its leaves are dark green, oval, undulate and oppositely arranged. Flower umbels are born in the axils of the leaves and typically bloom in summer. Individual flowers have light green to tan reflexed corollas and a white upright corona with a light pink to purple tip.

Photo by Emily Bell
Photo by Emily Bell

Like all members of the Asclepias genus, Curtiss’ milkweed is a larval host plant for Monarch, Queen and Soldier butterflies. However, the levels of poisonous cardenolides that the Queen and Soldier caterpillars are adapted to feed on but typically deter other browsers are low in Curtiss’ milkweed and therefore it is sometimes foraged by deer.

Family: Apocynaceae (Dogbane family)
Native range: Peninsular Florida
To see where natural populations of Curtiss’ milkweed have been vouchered, visit florida.plantatlas.usf.edu.
Hardiness: Zones 8B–10B
Lifespan: Perennial
Soil: Deep, extremely well-drained sand
Exposure: Full sun
Growth habit: Up to 4 feet, often leaning
Propagation: Seed

Curtiss’ milkweed is not commercially available. Visit a natural area to see it.

For more information on other Asclepias species, see these resources: