Palm Springs, Part 4: Cholla Garden

Part 4 is the final part. We made one other stop at the famous Cholla Garden in Joshua Tree National Park.



Cylindropuntia fulgida.



Fulgid, for sure.







I wonder about how these plants photosynthesize. Wikipedia says the leaves have been reduced to spines, but the spines don't appear pigmented, so where's the chlorophyll? In a unique sheath that covers the spine, apparently:

Part of the cacti family, the cholla uses CAM photosynthesis; an alternative pathway to convert energy from the sun into food. Mesophyll cells in the leaves convert carbon dioxide into organic acids. This allows the cholla to conserve water by keeping the stomata closed during the day; the traditional pathway for photosynthesis. It is the only cactus with sheaths which cover the spine.

The green pad is a conventional Opuntia's leaf. I would have guessed in the desert's constant, radiant light enough of it would reach the cholla's pad under the spines to drive photosynthesis but that does not appear to be how it works. Maybe one of you brainiacs will explain it in the comments.



This is the closest I've come to seeing cholla flowers, which I understand bloom in mid-summer. The flowers make fertile seeds, but most propagation happens asexually. Growing tips of the plant break off and blow around or get carried off by an animal until they find a spot to root. Hence, the dense stands.



Once, several years ago, I put my shoe too close to one of those little bits and sure enough, it hopped right on. There was a moment of slight panic when my attempts to kick it off caused it to dig in deeper. I managed to extract it without too much trouble using the edge and sole of my other shoe.

Paths through the "garden" make it a safe visit for the less clumsy, but there are still signs up to warn you about the danger of these plants.