Calamus tenuis Roxb.

Densely clustering slender rattan. Stems climbing to 20 m long or more, without sheaths 0.8–1.6 cm diam., with sheaths to 2.5 cm diam., internodes to 20 cm long. Leaves ecirrate; sheaths bright green, with scattered mid brown indumentum and abundant slightly reflexed narrow triangular brown-black spines with yellowish swollen bases, variable in size, the longest to 2 cm, the spine bases with lateral margins swept down, spine margins hairy when newly emerged; knee conspicuous, armed as the leaf sheath or unarmed; flagellum up to 2.5 m long; ocrea inconspicuous, dry, unarmed; petiole 8–15 cm long, longer in juvenile stems, armed laterally and abaxially with dark spines with swollen yellowish bases; rachis 60–100 cm long, curved; leaflets up to 40 on each side of the rachis, regularly arranged, shiny, somewhat arcuate, linear-lanceolate, usually most bearing a short yellowish bristle on the upper surface of the main vein near to the insertion on the rachis, otherwise with three prominent veins bearing black bristles adaxially, the mid vein only bristly on abaxial surface, margins bristly. Male and female inflorescences superficially similar, the male branching to 3 orders, the female to 2 orders, to 2.5 m long, including the terminal flagellum, and bearing numerous well spaced partial inflorescences; male rachillae to 25 x 0.5 mm, female rachillae to 50 x 1.5 mm. Mature fruit ellipsoid, 1.4 x 0.8 cm, covered with 16–17 vertical rows of white or pale yellow scales with dark margins. Seed rounded, c. 0.9 cm diam.; endosperm shallowly ruminate