Euphorbia horrida

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Euphorbia horrida Boiss CITES App II Euphorbiaceae
	Distribution: Found in the Wittepoort Mts. in the Willowmore District, var. striata is found 24km north of Steyterville, var. noorsveldensis is found 18km to the north of Jansenville, var. major is found 30km north of Willowmore.
	*Description:* Euphorbia horrida is a ribbed, columnar plant whose "spines" are actually the dried remnants of its flower stalks. There are many varieties of this species, perhaps natural hybrids between it and taller Euphorbias, giving rise to the big, spiny forms like E. horrida noorvalescens. If the spines weren't deterrent enough, most Euphorbias have poisonous, corrosive sap, so cultivated plants must be handled carefully.
	Flower: Up to five fertile and sterile peduncles appear on a single flowering eye, these "spines" can be 40 mm long, the main spine develops from a sterile peduncle. Involucre glands are green.
*Cultivation:* Established plants are easy to grow but the trick is establishing them. The eastern US is extremely humid during the growing season, making most Euphorbia cuttings rot before they can grow roots. Fortunately the larger forms tend to offset so enthusiastically there is lots of material to work with should the main stem suddenly collapse. E. horrida thrives on neglect, healthy plants are every bit as tough as Sanseverias, needing only one or two waterings during their stay indoors during the winter. During the summer, they enjoy average feeding and watering. Like Sanseverias, E. horrida isn't picky about soil but different clones vary in their tolerance of full sunshine. The general rule is that the smaller and rounder the variety, the less it can tolerate full sunshine.
Point of interest: Euphorbia horrida is a splendid example of a phenomenon known as parallel evolution. There are no true cacti native to the old world but many South African succulents have evolved to resemble new world cacti. (There is evidence of a native Rhipsalis, but this was doubtlessly introduced, perhaps by a migratory bird.)
Photographer, Grower: Roger L. Sieloff

Some examples demonstrating the variablility of E. horrida

Euphorbia horrida	Euphorbia horrida