On my quest to find all Milkweeds (Asclepiadoideae, the milkweeds, nowadays a sub-family of the Apocynacae, dog bane) that are native to San Diego County I was evaluating my current progress, and decided to take another look at the Climbing Milkweed that I photographed in the desert — and much to my own delight, found it to be Funastrum hirtellum (syn. Sarcostemma hirtellum), commonly known as Rambling Milkweed, Hairy Climbing Milkweed and Trailing Townula.
I regret that I didn’t spend more time photographing it, I thought it was Funastrum cynanchoides var. hartwegii at first. Mixing up F. cynanchoides and F. hirtellum is a mistake that’s easy to make upon first sight, especially without a direct comparison, because they can look extremely similar. There are a few differences that help to keep them apart:
- F. hirtellum is “hairy” (hence the name!😜) and that includes the leaves, vine, stems of the flower umbels, almost everything; F. cynanchoides isn’t hairy, except for the flowers, but it may require close inspection to see/not see the hairs.
- F. hirtellum may have almost white flowers, F. cynanchoides always has pink/magenta in them
- the leaves of F. cynanchoides have a wedge-shaped (cordate, hastate) base, which F. hirtellum lacks
- F. hirtellum only grows in the desert; F. cynanchoides grows in the coastal regions of Southern California (desert observations F. cynanchoides might be wrong)
Here are some photos of Funastrum hirtellum — all made in the desert. I added more after some desert hikes in 2022.