A kind reader sent me the article I asked for in this post, and I’ve filed it away in the database. Most of the writing I do as regards the paper will be for the book, but it’s relatively big news and I just have to engage in the sobersided, serious botanist version of a squee.

Taxonomists are forever arguing over whether certain closely related groups of organisms actually belong to the same species, or genus, or family, or name your taxon. The received wisdom is that these taxonomists tend to settle out into two roughly delineated groups, called “lumpers” and “splitters.”  In reality, there are taxonomists who maintain that there are several distinct kinds of both lumpers and splitters. Other taxonomists maintain that as few researchers advocate either splitting or combining all taxa, but rather make deliberate choices to lump or split based on the facts of the individual cases, that in reality “lumpers” and “splitters” should properly be considered members of their parent clade, “taxonomists,” and the split between “lumpers” and “splitters” be deemed obsolete.

Where was I?

Oh, yeah: Joshua trees. These matters are rarely settled easily. I would imagine that there may be significant argument among Yucca experts as to whether the paper referenced above is authoritative. There’s plenty of room for further study. Olle Pellmyr’s work on the two species of moths that each pollinate their own distinct population of Joshua tree, and the differences in both insect and floral morphology that have arisen between the two populations, suggest the possibility of reproductive isolation. But the jury’s still out, and the jury likes a good argument.

I can’t help it, though. This is so cool.

Lee Lenz, in the paper I asked for, posits that there are two species of Joshua tree. One Yucca brevifolia, grows in the west and north of Joshua tree country, near Los Angeles and up towards the White Mountains. The other, which grows east of Barstow, on Cima Dome, in half the tree’s range in Nevada and on into Utah and Arizona, Lenz has split into its own species: Yucca jaegeriana.

Squeee.