Euphorbia caput-medusae strong growth

A healthy Euphorbia caput-medusae plant may have many stems arising from the top of its subterranean caudex, the central stems rudimentary or less developed than those along the perimeter. The stem tops have short leaves for a while, the leaves dropping off early, leaving the green stem sides leafless with white scars on the tubercle tips.

Damage to the plant also brings about white colouring: Breaking the skin anywhere causes a prompt appearance of milky latex from the wound. Euphorbia latex is notorious, causing harm or discomfort to those that touch or ingest it. The latex serves as a deterrent to herbivores, a defence mechanism of the genus. Latex toxicity varies among Euphorbia species, causing damage of variable intensity; better to avoid contact in all cases.

Maybe some early Euphorbia plants, when the genus was still young had no latex and became extinct from serving as food (Frandsen, 2017; Manning and Goldblatt, 1996; iNaturalist).