Schizostachyum sp. (TH: Nakhon Si Thammarat)

Characteristics: Habit tight caespitose. Rhizomes pachymorph, short. Culms erect, bending outwards above and arching, over 12 m long by 3.5 cm in diameter [ultimate culm length not recorded, the plant received had a culm diameter of 4.5 cm]. Young shoots light brownish or light brownish green, apical truncate sheath margin dark red, blades upright, dark green; emerge from June to August. Culm-internodes mid-green, covered with short pale fuzz when young, slightly rough when old, 35–95 cm long from the base to the mid-culm, 95–50 cm long from the mid-culm to the upper culm, 50–15 cm from the upper culm to the apex; walls thin, 2.5–1.5 mm from the lower culm to the upper culm, to 7 mm on the basal culm, easily splitting, and small splits can be easily split into smaller ones. Culm-nodes not prominent, with a whitish ring below; sheath scar a raised blackish corky ring. Branches in a whorl, 12–16 per node, subequal, short, (30) 50–80 (140) cm long, the longest ones on mid-culm, horizontal or ascending, thin, 2–4 mm, occasionally rebranching; branch nodes very prominent by a thick blackish corky ring. Culm-leaves deciduous, convolute, and when old often stay rolled around the internodes of the lower unbranched culms, though detached from the sheath scar. Culm-leaf sheaths thickly papery, 17 cm long, light green, with a dark reddish tint towards the apex, or dark reddish on the apical truncate margin when young, light to dark brown when old, whitish to reddish brown short-hairy when young; sheath apex deeply concave-truncate; sheath base of the outer margin without a subcircular projection below the point of attachment; margins entire and eciliate, but the uppermost margin towards the edge of the sheath apex with short white early caducous ciliae. Culm-leaf auricles inconspicuous very low rims (less than 1 mm high), each extending from the blade base along the margin of the apex to its edge, blackish when young, with a few 5 mm long almost straight whitish early deciduous bristles. Culm-leaf ligule very short, inconspicuous, about 1 mm high, entire to subentire. Culm-leaf blade lanceolate, patent, reflexed and caducous when dry; margins convolute when dry; the attachment to the sheath 1.5–2 cm wide (about one-half to one-third of the width of the sheath apex). Foliage-leaves (3) 4–6 (8) per branchlet. Foliage-leaf sheaths glabrous or nearly so, green, apex truncate; margins entire and eciliate. Foliage-leaf auricles inconspicuous very low rims, dark green when young, slightly increasing in height towards the edge of the sheath apex, with few to many about 5 mm long almost straight whitish early deciduous bristles. Foliage-leaf ligule short, inconspicuous, 1–1.5 mm high, subentire. Foliage-leaf blades glossy mid-green above, dull green beneath, usually 23–32 (30) cm long by 3.5–4.5 (6) cm wide, but terminal blades on the main axis can reach a size of 53 cm × 10 cm, glabrous on both surfaces; base rounded or wedge-shaped, often asymmetrical; margins antrorsely scabrous; apex attenuate; midrib proximally prominent on both surfaces, light green, secondary veins almost inconspicuous, 2 × 10–12, cross veins none; pseudopetiole 5–9 mm long.

Uses: Culms suitable for basketry; plants for landscaping.

Cultivation requirements: Easy-growing; in part shade, on heavy moisture-retentive soil with good drainage.

Provisional identification: The plant BS-0322 was originally thought to represent Schizostachyum latifolium, but this is ruled out because of the low height and presence of prominent auricles in the latter species. The plant was checked to see if its vegetative parts matched those of Schizostachyum insulare, but the description of the latter is too incomplete to come to a judgment. The prominent corky ring on nodes of the plant resembles Schizostachyum grande, but the latter species differs in culm habit, culm sheath, and foliage leaf. The plant does not match Schizostachyum blumei (from Malaysia and Indonesia), which is smaller in culm size and has culm sheath auricles and a narrow long tapering culm sheath blade. The plant was also compared with Schizostachyum iraten, Schizostachyum jaculans, and Schizostachyum lima; their characteristics do not match those of the plant BS-0322.

Comments: The plant flowered sporadically on one culm in March 2012 for several months. No seed was found; flowering did not cause any harm to the vegetative parts; no later flowering was observed from 2013 to 2023.