Gigantochloa sp. (TH: Phang Nga)

Specimen: BS-0567 [BBG] (living plant), "Khao Nang Hong Pang Poi", ต. ถ้ำทองหลาง (Tham Thong Lang Subdistrict), อ. ทับปุด (Thap Put District), จ. พังงา (Phang Nga Province), altitude 100 m, coll. by C. S., #3071, 2 June 2010.

Characteristics: Habit caespitose. Rhizome pachymorph, short. Culms straight. Young shoots green, covered with blackish hairs; apex with sheath blades green, spreading; emerge from June/July. Culm-internodes terete, green, glabrous(?) or with scattered short whitish hairs when young, blackish when old, mainly on the 1/3 to 1/2 internode length below the nodes. Culm-nodes glabrous(?), not prominent. Branches several, the central one dominant, with two subdominant side branches, and several smaller branches; branching intravaginal; rebranching. Culm-leaves deciduous(?). Culm-leaf sheaths short, less than 1/2 of the internode length, green when young, light straw-colored when dry, densely covered with appressed short hairs, the hairs initially pale, soon changing to dark brown and blackish; margins dark short ciliate or eciliate(?); apex rounded or slightly convex-truncate. Culm-leaf auricles rim-like, low, dark green when young, little higher towards the ends, the ends reaching the sheath margin, or close to the margin, glabrous, without bristles, rarely with a single waved long pale slender bristle at the end. Culm-leaf ligule moderately high, margin subentire(?) or denticulate, brownish green when young, rarely with caducous, very short pale bristles. Culm-leaf blades reflexed, triangular on the basal and lower culm, lanceolate on the mid-culm and upper culm, the width of the junction with the sheath about 1/3 of the sheath apex, green when young, adaxially near the base densely dark brown hairy. Foliage-leaves about (6) 7 (8) per branchlet. Foliage-leaf sheaths green, dark brown hispid; margins eciliate. Foliage-leaf auricles inconspicuous, without bristles. Foliage-leaf ligule high, entire. Foliage-leaf blades green, lanceolate, base rounded to cuneate; apex attenuate; midrib proximally light green, proximally prominent beneath. Flowers and seeds are unknown.

Comments:

(1) The vegetative characteristics are incompletely described based on photos of an immature plant, which is now no longer in cultivation at Bambusetum Baan Sammi.

(2) The plant certainly represents a species of the genus Gigantochloa.

(3) It was believed that it could be Gigantochloa apus, but the vegetative characteristics match vaguely with this species, and identification remains unsettled as long as flowers are unavailable (Mu Chakkrapong, pers. comm., Facebook, 7 Oct. 2017).

(4) There are some similarities with the as-yet unidentified Gigantochloa species BS-0562 from Krabi.