Phyllanthus is the largest genus in the flowering plant family Phyllanthaceae. Estimates of the number of species in this genus vary widely, from 750 to 1200. Phyllanthus has a remarkable diversity of growth forms including annual and perennial herbs, shrubs, climbers, floating aquatics, and pachycaulous succulents. Some have flattened leaflike stems called cladodes. It has a wide variety of floral morphologies and chromosome numbers and has one of the widest range of pollen types of any seed plant genus. Despite their variety, almost all Phyllanthus species express a specific type of growth called "phyllanthoid branching" in which the vertical stems bear deciduous, floriferous (flower-bearing), plagiotropic (horizontal or oblique) stems. The leaves on the main (vertical) axes are reduced to scales called "cataphylls", while leaves on the other axes develop normally. Phyllanthus is distributed in all tropical and subtropical regions on Earth.