Description: Spiny succulent shrub with irregular basally clumping stems.
Stem: Erect, cylindrical 100 to 150 mm thick, up to 75 (150) cm tall.
Ribs: 10 to 20, wing-like, prominent.
Spines: The formidable rows of spines up to 40 mm long are actually the dried remnants of its flower stalks and are very rigid.
Flower: Very small green and yellow solitary cyathia, pedunculate. Involucre finely hairy with 5 glands and 5 large lobes. Involucres glands are green, blooms in summer.
Note: This plant is somewhat variable with many varieties and forms, and perhaps natural hybrids between it and taller Euphorbias, giving rise to the big, spiny forms like E. horrida noorvalescens, furthermore there are several other similar Euphorbia species (particularly Euphorbia polygona) which often looks a lot like some of the forms.