Gigantochloa sp. (TH: S) 2

Specimen: BS-0318 [BBG] (living plant), southern Thailand, without precise locality, coll. by C. S., CS-3015, received 7 Nov. 2009.

Characteristics: Rhizome pachymorph. Culm erect, bending outwards above. Young shoots emerge from April to August. Culm-internode 17–32 cm long, glabrous on the lower 2/3 of the internode length, scattered with short appressed black hairs on the upper third, with narrow yellowish stripes on the basal culm; thick-walled. Culm-node with aerial roots on the basal culm. Branch-bud solitary, rotund. Branches several, the central one dominant. Culm-leaves persistent. Culm-leaf sheath light green and with yellowish stripes when young, straw-colored when dry, with short appressed dark brown to black hairs; margins dark brown to black short-ciliate when young; apex strongly convex-raised, with a small triangular extension at the apex edges. Culm-leaf auricles rim-like, erect, low but long, extending with a gradually increased height from the blade toward the sheath apex edges, ending in broad ovate erect lobes, blackish when young, margins entire; oral setae none. Culm-leaf ligule very short, entire. Culm-leaf blade erect, triangular, plain dark green or with narrow yellowish stripes when young, straw-colored when dry; apex attenuate. Foliage-leaves 7–9 per branchlet, dark green. Foliage-leaf sheath glabrous, light green. Foliage-leaf auricles inconspicuous or absent; oral setae none. Foliage-leaf ligule 4–6 mm long; margins entire; apex pointed; outer ligule present. Foliage-leaf blade 34–44 × 5.5–6.5 cm, glabrous on both surfaces; base cuneate; apex acuminate; margins antrorsely scabrous; midvein prominent; pseudopetiole 1–2 mm long.

Comments: The identification of BS-0318 remains unresolved. It is most likely a species of the genus Gigantochloa. There are some similarities with Gigantochloa nigrociliata, mainly the extension at the apex edges of the culm-leaf sheath, but the apex seems to be much more convex-raised in BS-0318 than in Gigantochloa nigrociliata. Since the plant has left Bambusetum Baan Sammi, it cannot be re-examined.