Bambusa sp. (TH: Kanchanaburi 2)

Specimen: BS-0923 [E1-R10] (living plant); อ. ทองผาภูมิ (Thong Pha Phum District), Kanchanaburi, western Thailand, wild, from shady locality exposed to strong wind, coll. by บ. ต., received as "Bambusa species", 1 Dec. 2017.

Characteristics: Habit tight to open caespitose. Rhizome moderately long to long (30 cm), pachymorph. Culms straight, erect, slightly bending outwards above, ultimate height and diameter not known, current size (Sep. 2022) is over 7 m in height and up to 4 cm in diameter. Young shoots conical, sheaths densely farinose, thus appearing bluish, with more or less short dark hairs; culm-leaf blades spreading on the top, lower ones deflexed to horizontal, vivid green to dark green, with conspicuous pale bristly blackish auricles; emerge from late May to September (or October?). Culm-internodes terete, ca. 45–55 (65) cm long, dark green when young, dull medium to light green when mature, initially not or minutely covered with very thin chaffy farina, soon becoming glabrous; walls moderately thick to thick, 6–7 mm by 2.5 cm in diameter at 1.0 m above the ground. Culm-nodes glabrous, smooth, flat (slightly prominent in thin culms); nodal line horizontal; sheath scar not or marginally protruding; supranodal line discernible, with or without a slight ridge, about 0.6–1 cm above the nodal line (in culms with a diameter of 2.5 cm); initially with an easily removable white farinose, short-lasting ring-like band below the sheath scar; usually without aerial roots on the basal culm. Branch-buds solitary, rotund, from the basal node up. Branches several (ca. 5), unequal, central one slightly dominant; 1–2 m long, upright in an acute (20°–30°) angle; unbranched on basal and lower culm; branching intravaginal; branching development basipetal (from the apex towards the base); rebranching. Culm-leaves deciduous on branched upper nodes and unbranched lower nodes, often persistent and decaying on nodes of the basal culm. Culm-leaf sheath an isosceles trapezoid, near the base ca. 16 cm wide, apex horizontally truncate ca. 7.5 cm wide, height 11.5 cm long, roughly equals one-fourth to one-fifth of the internode length; texture papery to leathery; yellowish-green when young, light straw-colored with an initial pinkish or orange tinge when dry, brownish when old; usually covered with persistent short rigid blackish hairs (but glabrous, or initially pale pilose becoming glabrous and smooth in thin young culms), abaxially initially slightly farinose; margins eciliate. Culm-leaf auricles conspicuous lobes almost equal in shape and size, bent outwards, each ca. 2–3.5 cm wide, ca. 1 cm high; glabrous, blackish when young, medium brown when dry, initially with a pinkish tinge; margins finely toothed and long bristly; bristles initially pale, becoming pinkish and medium brown, somewhat undulated and spreading, 10–15 mm long; each auricle connected for two-thirds to three-quarters of the length with the margin of the sheath apex, and the outer end protruding the sheath margin for up to one third as a broad-ovate to sickle-shaped lobe, the other end wrinkly adnate to and contiguous with the pseudopetiolate margin of the blade. Culm-leaf ligule ca. 3–4 mm high, glabrous, blackish when young, pinkish mid-brown when dry, margin entire or subentire, but initially with early caducous long pale ciliae. Culm-leaf blades leathery, caducous or persistent, deflexed to reflexed, shorter than the sheath on the lower culm (ca. 3–4 cm long), about equal in length on mid-culm, lanceolate, pseudopetiolate; pseudopetiole of the blade base ca. 2 mm long and constricted to ca. 1–2 cm width of the junction with the sheath; blade glabrous and medium green on both surfaces, light straw-colored with an orange to pinkish tinge when dry; base rounded; apex acuminate to attenuate, sharp-pointed; margins eciliate, scaberulous, distally slightly incurved. Foliage-leaves (8–9) 12 per branchlet. Foliage-leaf sheaths somewhat keeled, light green when young, light straw-colored when dry, glabrous; apex convex-truncate; margins eciliate. Foliage-leaf auricles on lower branches of the mid-culm conspicuous, medium brown, ca. 6 mm long, sickle-shaped lobes, about equal in shape and size, each lobe connected for ca. 5 mm to the sheath apex, protruding; glabrous, margin with pale to pinkish waved spreading bristles, 10–20 mm long; auricles and bristles on the upper branches less conspicuous, in branchlets present only on the lower ca. 2–3 leaves, but usually not developed on the succeeding upper leaves. Foliage-leaf ligule a low glabrous rim, ca. 1–2 mm high, entire, light green to pinkish when young; outer ligule inconspicuous. Foliage-leaf blades rigid, long-lanceolate, size large, (15) 23–37 (39) × (3) 4–5 (6) cm, glabrous on both surfaces, medium green above, medium green with a bluish tinge beneath; base rounded to wedge-shaped; apex attenuate; margins antrorsely scabrous; midrib proximally distinct, proximally light green beneath; pseudopetiole ca. 2–3 mm long. Flowers and seeds are unknown.

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

Provisional identification: Bambusa sp.

Comments: The plant, BS-0923, resembles another unidentified species of Bambusa, BS-0918, from the same locality. The latter has a more open-spaced habit with a considerable amount of white waxy deposit on the culms, whereas BS-0923 has a tight to less open-spaced habit with culms that are only initially farinose, and are very little farinose. The culm-leaves of both specimens seem to be quite similar, as are the other characteristics. It may well be that these two specimens are conspecific.