Euphorbia horrida urchin

Euphorbia horrida is a spiny succulent shrub with irregular basally clumping stems. In age it will form tight clumps of upright columns up to a meter wide that closely resemble some cactus species. It also has clustered crowns of somewhat ferocious spines much like the true cacti.

Stem: 100 to 150 mm thick, up to 75 (150) cm tall, erect, cylindrical, blue-grey to grey-green and often with white stripes.
Ribs: 10 to 20, wing-like, prominent, deeply grooved between and more or less undulated
Spines: On the ribs there are 1-5 persistent peduncles, spiny and crowded together about 4-10 mm long and 1-4 formidable main spines up to 40 mm long and very rigid.
Leaves: Inconspicuous and ephemeral in the center of the plant.
Peduncles: Solitary 4-8 mm tall, hairy with small bracts.
Flowers: Very small green-yellow solitary cyathia approx. 4 mm in diameter. Involucre finely hairy with 5 glands and 5 large lobes. Pistil three-lobed. Involucres glands are green, blooms in summer.
Remarks: This plant is somewhat variable with many varieties and forms, and perhaps natural hybrids between it and taller Euphorbias.