The Alluaudia dumosa belongs to the family Didiereaceae. It is a shrub that is native to southern Madagascar. It grows in the semi-arid scrubland and thorn forests, and can reach up to 7.5 m in height. The mostly leafless, cylindrical, elongated, grey-green stems are upright to arching and sparsely covered in small spines. Small clusters of creamy white flowers bloom in midsummer from the branches. It is dioecious. The specific epithet dumosa means "shrubby", in reference to the growth habit of this species.