Calamus longisetus Griff.

Very robust clustering rattan. Stems climbing to 30 m long, usually less, without sheaths 3.5–5 cm diam., with sheaths 7–10 cm diam., internodes 10–45 cm long. Leaves ecirrate; leaf sheath dull green, densely armed with erect, spreading and reflexed flattened yellow-based spines of varying length, solitary or grouped in partial whorls, the longest to 6 cm long and 0.5 cm wide at base, interspersed with groups of much smaller needle-like spines, grey indumentum abundant between and on the spines; knee present but largely obscured by spines; ocrea inconspicuous; flagellum very robust, often to 10 m long; petiole 60–150 cm long, densely armed with solitary and grouped blackish spines with yellow bases, of size similar to those on the sheath; rachis to 3 m long, yellowish green, armed as the petiole; leaflets to c. 50 on each side of the rachis, irregularly arranged in groups of 2–7 and fanned within the groups, giving the whole leaf a plumose appearance, the longest to 75 x 4 cm, sharply spinulose along margins and upper-surface of mid vein and armed with black bristles to 2 cm long along mid vein on under-surface. Inflorescences flagellate, often to 10 m long, the male and female superficially similar, the male branching to 3 orders, the female to 2 orders, with up to 12 rather distant partial inflorescences, the longest to over 1.5 m long; male rachillae to 10 x 0.4 cm long, female rachillae to 45 x 0.5 cm. Fruit top-shaped, to 3.5 x 2 cm, with a triangular beak 0.4 cm long, and covered in c. 12 vertical rows of dull mid brown, horizontally banded with darker brown unchannelled scales with laciniate margins. Seed c. 2.7 x 1.7 cm, endosperm homogeneous. Seedling leaf not recorded.