Pachycaul
Pachycauls are plants with a disproportionately thick trunk, for their height, and relatively few branches. With certain pachycaul species, particularly the more succulent varieties, they are commonly referred to as "caudiciformes", a reference to their trunk development of a moisture-filled caudex for periods of drought. By comparison, trees with thin twigs, such as oaks, maples and Eucalyptus, are called leptocauls; those with moderately thick twigs, such as Plumeria, are called mesocauls. Pachycauls can be the product of exceptional primary growth or disproportionate secondary growth, as with the baobabs. The word is derived from the Greek pachy- and the Latin caulis.
All of the arboreal species of Cactaceae are pachycauls, as are most of the Arecaceae, Cycadaceae and Pandanus. The most extreme pachycauls are the floodplains, or river-bottom, varieties of the African palmyra, with primary growth up to thick, and the Coquito palm, with its primary growth measuring up to thick. The most pachycaulous cycad is Cycas thouarsii at up to diameter. The tallest pachycaul is the Andean wax palm, at heights of up to, and around in diameter. The most pachycaulous cactus are the barrel cacti, with primary growth up to diameter. The largest caudiciforme-type pachycaul is the African baobab ; one specimen of which, called the Glencoe baobab has a basal diameter of. However, this particular tree has suffered a severe trauma and is dying. Pachycauls also differ greatly in their rates of growth, from the half-man tree which grows only each year to the palm Pigafetta elata which can grow or more in one year.