Morphology of Pachypodium
Plants belonging to the genus Pachypodium vary widely from each other in some aspects, but also share a number of basic common traits. Each species is adapted to the specific environment which it inhabits, but all species of the genus share certain anatomical and metabolic traits, reflecting their common evolutionary ancestry. Pachypodium species vary widely in general form, or habit. The genus contains species ranging from the bottle-shaped P. baronii to the cigar-like P. lamerei to the branchless dwarf species P. brevicaule. Most species, however, are shrub or tree-like, ranging in height from 5 m or less to as much as 12 m. All species except for P. decaryi have spines on their branchlets, which are a modified form of stipule; some species have spines in other locations as well. In African species, the spines are clustered in groups of three, two large spines and one small one in the middle. In other species, the spines come in groups of two. The length of the spines varies from 1 mm in P. decaryi and P. sofiense to 75 mm in P. namaquanum. The wood of Pachypodium species is soft and cream-colored; their bark is, on average, 6 mm thick, and