; Alluaudiopsis marnieriana Rauh Didierea madagascariensis, commonly known as the octopus tree,[2] is a species of Didiereaceae endemic to the spiny thickets of southwestern Madagascar.

[3] It was first described scientifically by the French botanist Henri Ernest Baillon in 1880[4] and is the type species of the genus Didierea.

[5] Sohongy and sony come from the Tanosy dialect word songo meaning "lock of hair" or a rooster's crest or comb[6] possibly referring to its branches that sprawl upwards.

As with all members of the sub-family Didiereoideae, this is a semi-succulent woody, shrub to small tree.

[7] It is densely spiny and can grow up to 10 metres (33 ft) tall.