I just noticed that no one had identified this. I found out from another forum that these "tendrils" are actually seeds of the Erodium plant aka common stork's bill or redstem filaree. Believe it or not, the seeds act like drills. When they contact moisture, they very slowly twist around, driving the seed head into the ground. That's right -- they plant themselves! You can watch an amazing time-lapse video of it here:
https://www.youtube.com/watch?...
