Geometric Rarity: Euphorbia horwoodii f. cristata

A high-order collector’s prize, this cristate form transforms a rare Somali species into a living, convoluted sculpture of intricate tessellation.

1. Origin & History of Name: The genus Euphorbia is named after Euphorbus, the Greek physician to King Juba II of Numidia, who utilized the plant’s caustic latex for medicinal purposes. The specific epithet horwoodii honors Francis "Frank" Horwood, a renowned British horticulturist and succulent specialist who was instrumental in bringing rare Somali flora into cultivation during the mid-20th century.
2. Morphology: This plant features a fan-shaped growth mutation known as fasciation. The epidermis displays a striking "tile" pattern of dark green and silver-grey, mimicking the look of reptilian skin. In this cristate form, the traditional costae (ribs) are compressed into a singular, undulating growing ridge. The plant produces reduced, paired spines along the margins, though the primary aesthetic draw is the dense, brain-like folding of the succulent tissue.
3. Habitat & Origin: The base species is a rare wild succulent endemic to a very restricted area in Northeastern Somalia. However, the "crest" is a cultivar selection originating from a spontaneous mutation in cultivation. Because E. horwoodii is notoriously slow-growing and difficult on its own roots, these specimens are almost exclusively nursery-grown and often grafted onto hardy Euphorbia rootstock to ensure long-term sustainability and vigor.
4. Cultivation Profile:
   • Substrate: Requires a strictly inorganic, porous substrate. Use a mix of 80% volcanic rock, grit, or expanded clay to 20% coco-peat. Excellent drainage is non-negotiable for the Indian monsoon season.
   • Light: Thrives in bright, indirect light or filtered sunlight. In the Indian subcontinent, direct midday sun during summer can scorch the epidermis; use 50% shade netting.
   • Water/Dormancy: Extremely drought-tolerant. Water only when the substrate is completely dry during the growing season. Maintain strict dryness during winter or high-humidity periods to prevent fungal rot at the graft union.
5. Scientific/Historical Anecdote: Euphorbia horwoodii was considered one of the "holy grails" of succulent collecting following its formal description in 1978. It belongs to a group of Somali Euphorbias that evolved hyper-cryptic markings to blend into the limestone chips and shadows of their native environment, making them nearly invisible to herbivores—and botanists—in the wild.