Gigantochloa sp. (MY: Langkawi)

Characteristics: Habit tight caespitose. Rhizome pachymorph, short. Culms erect, straight, up to 18 m tall by 5.5 cm in diameter, with no lower branching. Young shoots emerge from April to June. Culm-internodes 40–57 cm long, dark green, with several narrow light green to yellowish green stripes, not farinose, glabrous, smooth, but distally with loosely scattered short blackish hairs, denser below the nodes; diameter 4–5.5 cm; thick-walled (walls 1.1 cm thick, with a lacuna diameter of 3.0 cm, culm diameter of 5.2 cm on a culm at 0.5 m above the ground). Culm-nodes glabrous, smooth, flat; sheath scar marginally producing less than 1 mm; supranodal line obscure, without a ridge, 6–10 mm above the nodal line; with aerial roots on the basal nodes. Branch-buds solitary, small, 10–15 mm wide, 6–10 mm high, from the basal nodes up. Branches several, thin (diameter < 1 cm), the central one slightly dominant (diameter ca. 1 cm); branching from about the 14th node up; infravaginal; rebranching. Culm-leaves persistent on the lower (unbranched) nodes and decaying on the culm, late deciduous on the (unbranched) mid-culm, deciduous on the upper (branched) nodes. Culm-leaf sheath thickly papery, brittle, 20–23 cm long, about half the length of the internode, irregularly and densely covered with short appressed blackish hairs; margins short dark ciliate when young, the ciliae long-lasting when old; apex slightly convex to obtusely triangular-truncate. Culm-leaf auricles rim-like, each about 25 mm long, very low, increasing height to 2–3 mm towards the rounded ends, not reaching the sheath margins, but often with a small triangular extension as the edge of the sheath apex, glabrous, dark colored when young, brownish when old; without bristles. Culm-leaf ligule short, 1–3 (5) mm, dentate with a few early caducous short bristles, becoming subentire and brown with age. Culm-leaf blade thickly papery, erect or somewhat patent, becoming patent to reflexed when old, lanceolate on the mid-culm and upper culm, almost triangular on the lower culm, much smaller than the sheath (between 1/3 and 1/2 of the sheath length), caducous. Foliage-leaves 9–12 per branchlet. Foliage-leaf sheaths keeled, glabrous. Foliage-leaf auricles rounded, oral setae none. Foliage-leaf ligule short, 1 mm, denticulate, becoming subentire with age. Foliage-leaf blades glabrous on both surfaces, 18–28 × 2.8–4 cm; margins antrorsely scaberulous; base rounded to wedge-shaped; apex attenuate; midrib proximally prominent; pseudopetiole 2–4 mm long, glabrous. Flowers and seeds are unknown.

Cultivation requirements: Easy-growing; in part shade to full sun, sandy loam to clay loam, normal moisture-retentive to moist with good drainage.

Provisional identification: Gigantochloa sp.

Uses: not recorded; shoots are bitter and not recommended for food.

Comments:

(1) The collector noted that this bamboo resembles Gigantochloa nigrociliata. However, a determination as to whether this is this species has not yet been confirmed. Both, BS-0286 and Gigantochloa nigrociliata have a similar culm-leaf, a dentate culm-leaf ligule, similarly shaped culm-leaf auricles, and, beyond the auricle, an extension that is triangular in the former and curved horn-like in the latter. The main differences are the culm-wall thickness (11 mm in BS-0286, 6 mm in Gigantochloa nigrociliata) of the basal culm, a ciliate margin of the culm-leaf sheath in BS-0286 (eciliate in Gigantochloa nigrociliata), a convex to obtusely triangular-truncate apex of the culm-leaf sheath in the former (horizontally truncate in the latter), and glabrous foliage-leaf blades in the former (pubescent beneath in the latter).

(2) The overall appearance of BS-0286 is similar to that of Gigantochloa wrayi, but there are differences between both species. The main differences are as follows: The culm-leaf sheath apex is slightly convex to obtusely triangular-truncate in the former (BS-0286) but horizontally truncate in the latter (Gigantochloa wrayi), the culm-leaf ligule is dentate and not lacerate in the former but is lacerate in the latter, and the culm-leaf blade is typically erect or somewhat patent in the former but reflexed in the latter. Further, the shape of the rim-like culm-leaf auricles is somewhat different between these species, and young shoots are green with a slightly bluish tint, with the sheaths densely and nearly completely covered with dark hairs in the former, whereas the sheaths are light green to yellowish-green with patches of dense dark hairs on the lower and middle parts of the sheath, and with the remaining parts glabrous or nearly so in the latter.

(3) This species could also occur in adjacent regions of neighboring Thailand, but records are not known.