Gigantochloa sp. (TH: Songkhla: Saba Yoi)

Specimen: BS-0554 [-] = CS-3056 (living plant), อำเภอ สะบ้าย้อย, Saba Yoi District, Songkhla, southern Thailand, coll. by C. S., received 31 May 2010.

Characteristics: Habit tight caespitose. Rhizome pachymorph, short. Culms straight, erect or bending [ultimate height not known]. Young shoots conical, green, with dark hairs; culm-leaf blades erect; emerge from August. Culm-internodes terete, ca. 30–40 cm long, green, with scattered appressed pale or brown hairs, not farinose, dull brown to brownish-green and glabrous when old; diameter to ca. 10 cm [ultimate diameter not known]; walls thick. Culm-nodes glabrous, smooth, not prominent; nodal line horizontal or slightly oblique; sheath scar not protruding; supranodal line obscure, without a ridge; with a narrow whitish ring below sheath scar when young; aerial roots none [in the immature plant]. Branch-buds solitary, subrotund, from the basal nodes up. Branches several, unequal, the central one dominant; unbranched on the basal (and lower?) culm; branching intravaginal; rebranching. Culm-leaves deciduous. Culm-leaf sheath thickly papery, green and with sparse pale to brown appressed hairs when young, light straw-colored and almost glabrous when dry, brownish and glabrous when old, ca. 1-third of the internode length; apex truncate, the middle part convex-raised or triangular; imbricated margin pale to brown densely ciliate, the other, non-imbricated margin eciliate or on its upper part sparsely pale ciliate. Culm-leaf auricles conspicuous, erect, broadly ovate-rounded, adnate and contiguous with the basal margins of the blade, extending along the sheath apex toward but not reaching the sheath margins, glabrous, entire, dark green when young. Culm-leaf ligule low, brown when young, margin with long pale fringes, 1 cm or a little longer. Culm-leaf blades rigid or leathery, persistent, erect or slightly deflexed, lanceolate on the mid-culm and upper culm, triangular on the lower and basal culm, much shorter than the sheath length on the basal and lower culm, the width of the junction with the sheath ca. half of the sheath apex width, glabrous on both surfaces, green when young, straw-colored when dry; apex acuminate, sharp-pointed; margins eciliate. Foliage-leaves (6) 8 (10) per branchlet. Foliage-leaf sheaths keeled on the back, green when young, straw-colored with an orange tint when dry, partly hairy, with pale to brown hispid hairs and appressed hairs, otherwise glabrous; margins eciliate; apex edge triangular and extending in height the auricles. Foliage-leaf auricles small rounded erect lobes, glabrous, entire, margins at their ends occasionally with a few (ca. 3) pale erect bristles. Foliage-leaf ligule conspicuous, ca. 3–4 mm high, brownish-green, margin with pale fringes ca. 3–5 mm long, becoming chaffy; outer ligule a conspicuous glabrous callus, 4 to 5-times wider than the auricle. Foliage-leaf blades thick, long-lanceolate, large, 22–34 (42) × 3–4.2 (5) cm, glabrous on both surfaces, green above, somewhat bluish-green beneath; base rounded to wedge-shaped; apex acuminate to attenuate; margins antrorsely scabrous; midrib distinct, proximally prominent, light green beneath; pseudopetiole 2–5 mm long. Flowers and seeds are unknown.

Provisional identification: A species of Gigantochloa. BS-0554 is similar to Gigantochloa auriculata s. Gamble, but in the former, the foliage-leaf auricles are smaller, the culm-leaf ligule and foliage-leaf ligule are taller and have long chaffy fringes, the apex of the culm-leaf sheath is without edge extension, the culm-leaves are shorter, and they are not densely hairy.

Comments: The plant is still immature, and its characteristics will have to be re-examined later.