CrimePaysButBotanyDoesnt

Texas Madrones - Relicts of the Past

Added 2024-10-03 00:33:02 +0000 UTC

Yesterday in West Texas I found two lone Texas madrones, Arbutus xalapensis, growing in a dry wash in the Chihuahua Desert. These trees serve as a reminder that the region used to be milder and slightly wetter, more akin to the Edwards Plateau further East where they still occur.

For anybody who doesn't know Madrones, they are a remarkably cool tree. They associate with their own type of Mycorrhizae, the Arbutoid Mycorrhizae, like all members of their subfamily including manzanitas (genus Arctostaphylos). They produce bird-dispersed fruit that is also edible to humans, though is not very palatable unless mixed with water into a drink. Their bark is cool to the touch and very smooth where it exfoliates. Their flowers look remarkably similar to blueberry flowers as they are in the same family. I was not expecting to find them here in this remote area in a very dry region, and it makes sense they were growing on what is essentially a little divot in the ground where the sun could not bake their root systems and they received more moisture during a rain than the surrounding desert flats.

Learning about plants like this that only occur in what we call refugia - vestigial sites that provide them an island of suitable habitat within a larger habitat that is mostly unsuitable - was part of what initially got me so excited about biogeography and the study of plant communities. I have similar phenomenon with Arizona cypress at Cooke's Peak, New Mexico Doug For and Chestnut Oak in a small canyon near the Texas- New Mexico Border. These plants occurring in places like this offer a window into the past and how the plant communities and climates have changed over the recent millennia.