Bambusa sp. (TH) 1

Specimen: BS-0922 [C7] (living plant), Thailand, without precise locality, in cultivation in Nan Province, received from ต. น., 22 Nov. 2017.

Habit unicaespitose, dense. Rhizome pachymorph, short [n.v.]. Culms straight, erect, slightly bending outwards above; ultimate height not yet known. Young shoots conical, sheaths green, farinose, thus appearing whitish to bluish-green, with appressed blackish hairs; sheath margins eciliate; culm-leaf blades green, spreading, pale-bristly auricles blackish; emerge from May to October. Culm-internodes terete, 45–60 cm long, green, initially thinly or thickly farinose, thus appearing bluish-green, with short appressed blackish hairs, distally abundant, proximally scarce, lower internodes initially with narrow pale yellowish stripes; becoming plain dull light ocher and slightly scabrous with age; ultimate diameter not yet known; thick-walled. Culm-nodes glabrous, smooth, not prominent; nodal line horizontal; sheath scar marginally protruding, 0.5 mm; supranodal line usually obscure, without a ridge, 1–1.5 cm above the nodal line; without a farinose transverse band below or above sheath scar; aerial roots none. Branch-buds solitary, kite-formed, from the basal node up. Branches several; the central one somewhat dominant, to about 2 m long; lower culm unbranched; branching intravaginal; rebranching. Culm-leaves (early?) deciduous. Culm-leaf sheaths ca. 12 cm long, shorter than the internode, about 1-third of the internode length, rigid, pale yellowish-green to yellowish-orange when young, thinly farinose, partly scattered with short rigid blackish hairs; apex broadly rounded, the middle part concavely depressed, symmetrical; margins eciliate. Culm-leaf auricles large lobes, 1.5–2 cm wide, ca. 0.6 cm high, roughly equal in shape and size, the ends rounded and upcurved, adnate to and contiguous with the basal margins of the blade and sheath apex, each auricle extending towards the sheath margin and protruding ca. 5–10 mm, outward-bent, corrugated, initially orange or dull blackish when young, brownish with age, glabrous; margins with pale, irregularly waved bristles to 15 mm long. Culm-leaf ligule ca. 2–3 mm high, blackish; margin entire. Culm-leaf blades leathery, deflexed to reflexed, persistent(?), broadly lanceolate, the base ca. 3 cm wide, constricted to ca. 1.5 cm at the junction with the sheath apex, glabrous on both surfaces, light green when young; apex acute to acuminate, sharp-pointed; margins eciliate, scaberulous, incurved. Foliage-leaves (5) 6–7 (8) per branchlet. Foliage-leaf sheaths light green to yellowish-green when young, brownish when old, glabrous; apex truncate; margins eciliate. Foliage-leaf auricles and bristles not developed but are in branchlets occasionally present in rudimentary size on the lower ca. 1–3 leaves. Foliage-leaf ligule, low, 0.5 mm high; margin rounded, entire; outer ligule a low glabrous rim or ridge. Foliage-leaf blades long-lanceolate, (9) 15–28 (33) × (2) 3–4 (4.5) cm, glabrous and medium green on both surfaces, with a faint bluish tint beneath; base rounded to wedge-shaped; apex attenuate; margins antrorsely scabrous; midvein proximally prominent and light green on both surfaces; pseudopetiole ca. 2 mm long. Flowers and seeds are unknown.

Cultivation requirements: Easy and fast-growing; in part shade to full sun, sandy loam to clay loam, normal moisture-retentive to moist with good drainage.

Provisional identification: Bambusa sp.

Comments: The vegetative characteristics of BS-0922 are very similar to those of two unidentified Bambusa species from Kanchanaburi: BS-0918 and BS-0923, to which BS-0922 may be closely related.