Species in this genus are mostly climbers with long, slender, flexible stems, but some are erect shrubs and some have no apparent stem (). They may be clustering or single-stemmed. The leaves are with an even number of leaflets, in the climbers they may be variously barbed or clothed in spines (including the leaf sheath). Climbers also produce armed
tendrils – either from the leaf sheath, in which case it is known as a 'flagellum', or as an extension of the midrib and known as a 'cirrus'. Climbing species will often reach the forest canopy, and one plant was recorded as being long. In some species, such as
Calamus rudentum, the inflorescence also has a flagellum. All species are
dioecious, meaning that male and female inflorescences are produced on separate plants. They both arise from the and are pendant and branched, and may variously have barbs, spines or cirri. The fruit rarely contain more than one seed, the thin
sarcotesta is covered by an external layer made up of rows of small overlapping scales similar in appearance to a snakeskin. ==Taxonomy==