CrimePaysButBotanyDoesnt

One of Texas' Rarest Plants - Paronychia congesta

Added 2024-10-13 20:42:06 +0000 UTC

One of Texas' Rarest Plants - and one of my new favorites - is this guy, Paronychia congesta (Carnation Family - Caryophyllaceae), known only from 2 sites in Deep South Texas where it occurs on barren and harsh Caliche exposures.

Caliche is basically a natural cement. It's a product of dissolution of calcareous country rocks by rainwater and subsequent precipitation of those weathered minerals later on, forming a natural cement-like material. For whatever reason, the caliche here is extensive, so much so that the surrounding Thornscrub can't grow on it, but oddball plants like Liatris punctata var. mexicana and this Paronychia can.

I know the genus Paronychia from other sites across North America. It's a genus that tends to thrive on rocky and dry microsites including rock exposures and cliff outcrops where it won't be smothered or out-competed by other faster-growing and larger plants. The tiny star-shaped flowers are unmistakable. Paronychia jamesii is a more common species in the genus that occurs throughout Texas.

Why Paronychia congesta is so rare is a mystery, and how old is as a species and why it speciated in the first place is even more fascinating and curious to me. Did it once have a more extensive range? Does it occur slightly further South in Mexico on rocky exposures in the Sierra Madre? How imperiled is it? Apparently enough to put it on the endangered species list, which of course affords no protection in a state line Texas but give it a designated status on paper, at least.