Calamus impar Becc., Ann. Roy. Bot. Gard. (Calcutta) 11(App.): 19 (1913)

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Map uses TDWG level 3 distributions (
Borneo present (World Checklist of Arecaceae)B
A poorly known species found in western Kalimantan. (Dransfield, J. & Patel, M. 2005: Rattans of Borneo, an interactive key.)A


  • It is probably merely a form of Calamus javensis. (Dransfield, J. & Patel, M. 2005: Rattans of Borneo, an interactive key.)A


  • Habit - Climbing; not branching in the forest canopy; not dying after flowering. Plants dioecious.
    Leaf-sheath - Tubular for most of its length; stem and sheath together 0.5-0.6 mm; flagellum long; knee present; with spines similar to the rest of the sheath. Sheath surface lacking small horizontal ridges; without hairs or minute spines; with scales on surface; grey. Leaf sheath without spines, or with sparse spines; spines persistent; upward pointing; of more or less the same size; the larger spines tapered; the longest, excluding those at the mouth of the sheath less than 1cm. Spines straight. Spines mostly not grouped. Spines around the leaf sheath mouth far fewer than on the rest of the sheath. Ocrea - Present; not diverging at an angle from the stem; tattering; unarmed. Leaf-stalk - Present, usually greater than 3cm; armed; irregularly; spines present in channel on upper face of petiole. Large well-defined auricles absent; blotches on petiole absent. Leaves - Ecirrate; rachis armed; not hairy. Scales absent from leaflet surfaces. Leaflets sessile; 1 to 10 on each side of rachis; irregularly spaced and parallel; held in a single plane; spathulate; the leaflet tip cucullate (hooded). Longest leaflet 7-18 cm; 2 to 5cm wide; with none or very few bristles; the margins with no or very few bristles. Leaflets scarcely plicate; the veins not radiating; midrib not raised and prominent. Lowermost leaflets not reflexed across the stem. Apical leaflets joined to 2/3; not less than 4 cm long.
    Inflorescence - Inflorescence axis erect along the axis, with clawed spines on the primary bracts; not rooting at its tip; much longer than the leaves; the first bract not enclosing the inflorescences at anthesis. Partial inflorescence present; bracts at the base of the partial inflorescences wholly tubular with a neat mouth or a small open limb, much shorter than the partial inflorescence. Rachilla lacking an enclosing bract; not at all pressed against the subtending bract. Flowers arranged in two rows. Male rachillae not less than 1 cm long. Bracts on the rachillae not net-like. (Dransfield, J. & Patel, M. 2005: Rattans of Borneo, an interactive key.)A


    A. Dransfield, J. & Patel, M. 2005: Rattans of Borneo, an interactive key.
    B. World Checklist of Arecaceae