Euphorbia horrida is a spiny succulent shrub with irregular basally clumping stems. In age it will forms tight clumps of upright columns up to a metre wide that closely resemble some cactus species. It also has clustered crowns of somewhat ferocious spines much like the true cacti. This plant is somewhat variable with many varieties and forms, and perhaps natural hybrids between it and taller Euphorbias. One great example is the Snowflake.