Asclepias viridula

Asclepias viridula is a perennial herb of wet, open habitats, including meadows, pitcherplant bogs, seepage slopes, longleaf pine savannas, and flatwoods, that is endemic to the southeastern United States. It is historically found disjunctly in northeastern Florida and the Florida Panhandle and adjacent southeastern Alabama, and while southern Georgia has been included in some flora distributions, no specimens exist. Over half of the Florida counties where this species has been documented may now be historical or extirpated, including all seven counties in northeastern Florida. There are an estimated 36 occurrences remaining, many of which are located on protected lands within Apalachicola National Forest and Fort Gadsden State Historic Site, with additional populations at Eglin Air Force Base and Tyndall Air Force Base. Occurrences face threats from development, conversion to pine plantation and site preparation for forestry management, fire suppression, rights-of-way maintenance, and invasive species. Habitat of protected occurrences could be improved by burning every two to three years and thinning overstory to decrease competition. Searching for new occurrences in northeastern Florida, southern Georgia, and southeastern Alabama is a high priority.

Asclepias viridula is endemic to the southeastern United States where it was historically found disjunctly in northeastern Florida and the Florida Panhandle (fifteen counties total) and adjacent southeastern Alabama (Houston County); while southern Georgia has been included in some flora distributions, no specimens exist (Chafin 2000, FNA 2023, Weakley and the Southeastern Flora Team 2025). Range extent was estimated to be 13,003 square kilometers using herbarium specimens, photo-based observations, and NatureServe Network occurrence data documented between 1994 and 2025 (GBIF 2025, iNaturalist 2025, NatureServe 2025, RARECAT 2025, SEINet 2025).

By applying a 1 km separation distance to herbarium specimens, photo-based observations, and NatureServe Network occurrence data documented between 1994 and 2025, it is estimated that there are 36 occurrences rangewide (GBIF 2025, iNaturalist 2025, NatureServe 2025, RARECAT 2025, SEINet 2025). The most recent observation in 1994 from northeastern Florida in Clay County has a closed canopy based on aerial imagery and may no longer have open habitat to support this species (Orzell and Bridges 22791 (USF), Rosner-Katz, pers. comm., 2025).

This species faces threats from habitat loss and degradation. Loss of habitat may be due to development or conversion of pine flatwoods to slash pine plantations. Intense site preparation for forestry management, including dozing, root raking, or chopping, have negative impacts on this species, exacerbated by canopy closure from planted pines (Kral 1983). Places where there is residential development also have fire suppression, interconnecting the highest threats (A. Schotz, pers. comm., 2016).

The primary habitat degradation threats are fire suppression and rights-of-way maintenance. Fire suppression is likely to degrade existing habitat, increasing woody encroachment and possibly invasive species cover, resulting in the possible loss of populations (Kral 1983, NatureServe 2025). Even where habitat is managed, burning takes place at less frequent intervals than what is ideal. At least seven occurrences are located within roadside or powerline rights-of-way, and maintenance activities, such as herbicide and mowing, may negatively impact populations; however, mowing outside the flowering period may be beneficial to reduce woody plant encroachment (NatureServe 2025). Additional habitat degradation threats include invasive species, such as feral hogs and black titi (Cliftonia monophylla) (NatureServe 2025).