Maclurochloa montana

Specimen: BS-0274 [†] (living plant), Chiang Mai Province, Doi Pui (ดอยปุย), in moist evergreen forest, on eastern slope near the roadside at about 1,550 m alt., C. S. 13 Sep. 2009.

Characteristics:

(1) Habit caespitose, a tall diffuse clump, irregular and shapeless. Rhizome pachymorph, short-necked [n.v.]. Culms ascending below, scrambling and leaning into nearby vegetation, not self-supporting; the lower culm usually unbranched, plant height about 6 m, but culms are longer. Young shoots yellowish, without hairs, emerge from August to October. Culm-internodes terete, (35) 42 (46) cm long, diameter up to 4 cm, covered with short whitish hairs in the upper part when young, dull light green and smooth to slightly rough when old, solid or nearly so on the basal culm, thick-walled on the mid-culm and upper culm (ratio wall width: radius ≈ 1 : 2 for culms with diameter 0.3–2.5 cm). Culm-nodes without aerial roots, not or slightly prominent, with a small corky girdle below the sheath scar, with a white ring below the girdle. Branch-buds solitary on each node, very large, width extending half the culm circumference or nearly so, and height almost as long as wide [on culms with diameter 2.0 cm, bud width = 3.2–3.6 cm, bud size on thicker culms not observed]. Branches many, with a central single dominant branch with a diameter half to two-thirds of the main axis and several meters long, or as big as (or slightly bigger than) the main axis, and replacing the main axis if disturbed or damaged, or remaining as a dormant bud (usually on the lower culm), side branches usually 6–12, 1–2 mm thin, 0.4–1.2 m long, rebranching, a major branch (secondary axis) can reach to 6 m and more [one thin secondary axis has reached about 10 m in BS-0274], branching extravaginal [possibly infravaginal on the upper culm, not observed]. Culm-leaves deciduous. Culm-leaf sheath shorter than the internode, thick and brittle, glabrous and smooth, but occasionally with a few scattered caducous soft white hairs, bright orange when young, with a reddish tint towards the base, the sheath apex horizontally truncate with slightly raised shoulders, margins eciliate. Culm-leaf auricles long, very low rims, each rim with a protruding, caducous lobe, dark reddish brown, fringed with a few caducous short white bristles. Culm-leaf ligule short, orange, finely toothed, fringed with caducous up to 1 cm long white bristles. Culm-leaf blade lanceolate, reflexed, almost as long as the sheath, occasionally caducous. Foliage-leaves (3) 5 (6) per branchlet. Foliage-leaf sheaths glabrous, light green to yellowish green, keeled, apex truncate, margins eciliate. Foliage-leaf auricles none. Foliage-leaf ligule short, finely toothed, fringed with caducous short white bristles. Foliage-leaf blades lanceolate, 14–19 cm long, 2.7–3.0 cm wide, glabrous on both surfaces; base unequally rounded; margins antrorsely scabrous; midrib slightly prominent, secondary veins 2 × 5–8, cross veins none; pseudopetiole 2–3 mm long. Flowering branches leafless, several meters (3 m) long, occasionally rebranching. Pseudospikelets in stellate short clusters, bracteate, (2) 8–14 cm apart, laterally compressed, breaking up early; filaments free, anthers pale yellow [other flower characteristics not examined].

(2) Culm size dimensions: Basal culm 0.15–0.25 m above the ground, culm diameter 2.6–3.2 cm, solid; lower culm 1.2–2.3 m above the ground, culm diameter 1.9–2.0 cm, wall thickness 0.7–0.95 cm, lacuna diameter 0.5–0.1 cm; mid-culm more than 3 m above the ground, diameter 1.2 cm, wall 0.3 cm, lacuna 0.6 cm; mid-culm, diameter 0.8 cm, wall 0.2 cm, lacuna 0.4 cm; upper culm, diameter 0.6 cm, wall 0.15 cm, lacuna 0.3 cm; upper culm, diameter 0.3 cm, wall 0.1 cm, lacuna 0.1 cm. Internodes towards the culm base are with a small lacuna and finally solid (or, a small lacuna filled with pith appearing solid).

Cultivation requirements: Grows well in part shade, on heavy moisture-retentive soil with good drainage.

Provisional identification: While in the vegetative state, this bamboo was misidentified as a species of Melocalamus (Melocalamus compactiflorus var. fimbriatus), or Neohouzeaua (Neohouzeaua helferi). When flowering, the plant was assumed to be a species of Maclurochloa, and after a closer look at the description of Maclurochloa montana, which is the only known species of the genus and distributed in Peninsular Malaysia and southern Thailand, the assumption was strengthened. Specimens of the flowering plant were distributed for examination.