Curtiss’ Milkweed

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This week’s wild flower is endemic to Florida. Curtiss’ Milkweed, Asclepias curtissii, is also on the State’s rare and endangered list. Curtissii is found in scrub habitats in 23 counties in the central and southern peninsula. It is a herbaceous perennial that dies back in winter and may or may not grow back in the following season.  Populations are localized and tend to be very small.

Crutissii has a single erect reddish main stem that grows from a thick root stock to a height of about two feet. Dark green oblong leaves are arranged in pairs along the stem separated by gaps between the pairs. Leaf margins are wavy.  Flower clusters grow from the leaf axils at the junction of leaf and main stems. Two or three dozen flower buds can appear in a single cluster. One to three blooming clusters can appear at the same time.

The flower structure is highly complicated.  A flower bud opens forming a calyx of five green sepals. Covering the sepals is a downward hanging corolla with five faded green petals.  At the center of the corolla is a fused column of male and female sex organs similar to the column found in orchids.  Surrounding the column are five tiny and bright white florets with a diameter of about ¼ inch. After pollination, seed pods appear bearing tiny seeds with long silky hairs to aid in wind dispersal.

The name Milkweed comes from white sap found in the species of the genus Asclepias. The sap is toxic.  The specimen in the photo was shot in Koreshan State Park.