Gigantochloa sp. (SG)

Distribution: THAILAND: introduced, in cultivation, rare. — SINGAPORE, cultivated.

Characteristics: Habit caespitose, tight clump. Rhizome pachymorph, short. Culms straight, erect below, slightly bending outwards above, 3 m long [ultimate culm length unknown]. Young shoots [not yet observed], emerge late. Culm-internodes terete, 18–27 cm long, green, with light green to yellowish green stripes of various widths, initially slightly farinose, scattered with short hairs or almost glabrous, slightly rough, diameter 1 cm [ultimate diameter unknown]; walls [not yet observed]. Culm-nodes glabrous, smooth, not prominent, nodal line horizontal, supranodal line more or less obscure, without a ridge, or with an insignificant ridge, ca. 9 mm above the nodal line; aerial roots none. Branch-buds solitary [not yet observed], possibly from the basal node up. Branches initially 3, unequal, the central one slightly dominant, with 2 subdominant side branches, and 1–2 slender branches, branchless on the basal culm; branching intravaginal; rebranching. Culm-leaves deciduous on branched nodes, persistent on unbranched nodes of the basal culm. Culm-leaf sheaths parabolic, 8–12 cm long, ca. 1/3–1/2 as long as the internode, leathery, rigid, light green with an occasional pale stripe when young, light straw-colored when dry, densely or loosely scattered with appressed and stiff short blackish hairs, or glabrous or nearly so; apex truncate; margins eciliate. Culm-leaf auricles rim-like, 0.5 mm high, slightly higher and rounded at the ends, erect, adnate to and contiguous with the basal margin of the blade,  extending to the sheath margin; glabrous, entire, light brownish when young. Culm-leaf ligule low, light brownish when young, entire. Culm-leaf blades deflexed to reflexed, late caducous, lanceolate. Foliage-leaves 6–12 (14) per branchlet. Foliage-leaf sheaths keeled, green when young, glabrous or with scattered appressed short dark hairs; apex glabrous, green to reddish green when young, apex extension triangular to horn-like; margins eciliate. Foliage-leaf auricles inconspicuous low rims, glabrous, entire, eciliate. Foliage-leaf ligule inconspicuous, outer ligule an inconspicuous low glabrous callus. Foliage-leaf blades, thick, lanceolate, 20–40 × 2.5–7.5 cm, glabrous on both surfaces, green; base rounded to wedge-shaped, often not symmetrical; apex attenuate; margins antrorsely scabrous; midvein distinct, proximally prominent and light green beneath; pseudopetiole 3–7 mm long.

Comments: One specimen with largely similar characteristics is BS-0317, provisionally classified as Bambusa species. Both have an apical extension of the foliage-leaf sheaths, but this extension is rounded in BS-0317, not horn-like.