Marvelous Milkweed

After we being plagued by a miserable amount of mosquitoes in the hammock area at the South Oslo Riverfront Conservation Area (SORCA) on our orchid stroll on June 18, 2022, we ventured in the sunnier and scrubbier part of the preserve. Mariam Greene miraculously spotted a Curtiss’ milkweed (Asclepias curtissii) growing along the ever-widening trail.

This endemic, extremely rare & endangered perennial plant is deciduous. It grows only in sandy, dry scrub in peninsular Florida. Curtiss’ milkweed is disturbance-driven and may not re-sprout every year. Mowing and hurricanes have benefited the population at SORCA. Often, in less overgrown natural areas, Curtiss’ milkweed is found growing on the aprons of gopher tortoise burrows and around harvester ant mounds.

Curtiss’ milkweed prefers full sun. It tends to be lanky especially in shadier conditions, growing from 2 to 4′ tall. Its opposite leaves are dark green with undulate edges. Its white flowers are held in an umbel at the end of the stems …

Flowering occurs from June through September, and the flowers last about five days. It takes about 60 days for a fruit pod (follicle) to form. Small butterflies like the Ceraunus blue and hairstreaks are thought to be its pollinators. Each fruit contains about 68 seeds and which, as is characteristic of milkweeds, are wind-distributed.

Another endemic white-flowered milkweed is found in Indian River County: Florida milkweed (Asclepias faeyii). Also called Faey’s milkweed, this uncommon perennial plant occupies a niche space between mesic and scrubby flatwoods in south and south central Florida and is shown below at Sebastian Harbor Preserve. As with Curtiss’ milkweed, the white flowers of Florida milkweed, shown below, are held in an umbel. The flowers of Florida milkweed have a distinctive dark magenta center where the pistil and stamen are held. Viewed from above, the petals point outward giving each flower a star-like shape …

Neither of these rare white-flowered milkweeds is available in the nursery trade. Other milkweed species are commercially available and should be planted in preference to non-native milkweeds as a larval host for monarch and queen butterflies.