Euphorbia decaryi is a small, perennial, leafy succulent with a shrub-like development and beautiful wavy, zig-zag edged leaves. It is a mat-forming species and spreads almost horizontally on the ground by means of rhizomes. The Euphorbia decaryi growth form illustrates the typical horizontal habit of most Madagascan euphorbias. It is one of the most popular and widely grown of the Madagascan euphorbias.

Succulent, long, irregular, corky, root-like partially subterranean, not very thick around, more or less angled and spiralled covered with scale-like leaves. Above ground the stems are erect or creeping.

Evergreen or semi-deciduous, tufted in rosettes at the stems tips, deep-red and green coloured, narrow, very succulent, highly undulate, folded and crisp with raised veins and very attractive. Leaves in summer and under stress assume a nice coppery-bronze colouring.