The Didieraceae is a small family of unusual spiny-stemmed succulents endemic to Madagascar. Their extreme spinyness mimicks the Cactaceae, but they have no relation to that plant family. Their thin leaves during periods of active growth makes them easy to distinguish.

Southern Parks: Andohahela

Andohahela National Park, in southeast Madagascar, is remarkable for the extremes of habitats that are represented within it. The park covers 760 square kilometers of the Anosy mountain range, the southernmost spur of the Malagasy Highlands. These mountains form a natural barrier to the moist trade winds that blow from the east, causing a rainfall of 1500 to 2000mm per year on their eastern side that supports one of the few rainforests south of the tropic of Capricorn. At the western edge of the park, the rainfall is just 600 to 700mm per year and the resulting vegetation is a dry spiny forest characteristic of southern Madagascar. In the area between these two climatic extremes is a unique transitional forest known as the Ranopiso transition, which is characterized by the locally endemic triangular palm, Dypsis decaryi. The variety of habitats within Andohahela is mirrored in the richness of species that are found there. Fifteen species of lemur have been recorded, including one of Madagascar's most emblematic species, Verreaux's Sifaka.