Pseudosasa sp. (TH: Chiang Mai, Loei)

Thai name: No known records.

Distribution: THAILAND (North): Chiang Mai Province: Doi Inthanon; (North-East): Loei Province; wild (native or naturalized) and cultivated.

Local distribution: In cultivation by the Royal Project at Doi Inthanon, Doi Ang Khang, and Mae Hia, both Chiang Mai Province. (S. Sungkaew & al., 2008: 11 [#1073])

Culm size: Height about 3–4 m, diameter to 1 cm.

Characteristics (based on BS-0364 and BS-0411): Rhizome leptomoph. Culms terete, flattened above branches, erect below, nodding above, usually unbranched on the lower and mid culm. Culm-internodes green, glabrous, smooth, with a ring of whitish wax below nodes when young, early fading, thick-walled (lacuna less than 1 mm by a diameter of 6 mm). Culm-nodes with prominent nodal ridge; infranode pronounced, green, smooth. Branches subequal, thinner than the main culm, typically 3 on the mid-culm nodes, or 4–6 on the upper nodes. Culm-leaf sheath on unbranched nodes usually late deciduous, occasionally persistent or loosely attached and decaying on the culm, early deciduous on branched nodes, whitish to light straw-colored and glabrous when dry, with scattered tiny blackish dots, about one-half to one-third (one-fourth) as long as the internode. Culm-leaf auricles tiny, reflexed, oral setae long, both early caducous. Culm-leaf ligule 1 mm long, convex. Culm-leaf blade small, triangular, reflexed, not erect, and early caducous. Foliage-leaves (3) 4–6 (7) per branchlet. Foliage-leaf sheaths green, or yellowish green to brownish green, glabrous, apex concave, on both sides with several, usually straight up to 6 mm long pale bristles. Foliage-leaf auricles inconspicuous or none, with several, straight or twisted up to 6 mm long pale bristles. Foliage-leaf ligule inconspicuous. Foliage-leaf blades 12–23 (29) × 2–3.5 (4) cm, tough, slightly asymmetric, mid-green to dark green above and not shiny, green to bluish-green beneath, tessellate, glabrous on both surfaces; base rounded to wedge-shaped; apex attenuate; margins antrorsely scabrous; midrib prominent beneath, yellowish-green; pseudopetiole 5–7 mm long, glabrous. Flowers and seeds are unknown.

Uses: Not recorded.

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

Provisional identification: This could be a species of Pseudosasa subg. Sinicae, a subgenus that is characterized by usually three branches per node and deciduous culm sheaths. In the overall appearance of the currently still immature plants, the unidentified species is similar to Pseudosasa japonica (subg. Pseudosasa), which has a solitary branch per node and persistent culm sheaths. The unidentified species has short culm sheaths, whereas in Pseudosasa japonica, culm sheaths are almost as long as the internode. The culm sheaths of the unidentified species have bristly auricles, whereas these are lacking in Pseudosasa japonica. However, I am not yet convinced that the unidentified species belongs to Pseudosasa. Its vegetative parts resemble Sinobambusa tootsik. The unidentified species shows flattened internodes above branches, which are characteristic of Sinobambusa. The characteristics need to be observed in more detail when the unidentified species reaches a mature height, and the young shoots of the unidentified species also need to be observed.

Distribution: THAILAND (North-East): Loei Province.

Distribution: THAILAND (Central): Phitsanulok Province.

Comments: A Pseudosasa species is suspected to occur in Phitsanulok (Classification of Bamboo, 2012 [#1223]), but no further information is available.