Pseudostachyum polymorphum

Synonyms: Schizostachyum poly­morphum (Munro) R. B. Majumdar, in S. Karthikeyan & al., Fl. Ind. Enumerat., Monocot., 1989: 282; Schizostachyum leviculme McClure, Sunyatsenia 6, 1941: 43; Pseudostachyum wakha Brandis ex É. G. Camus, Bamb., 1913: 162.

Thai names: ไผ่ออลอ (phai o lo); ไผ่ออ (phai o), ไผ่หมอก (phai mok). — T. Smitinand, 2001 [#1003].

Distribution: THAILAND (North-East): Loei Province; (Central): Phitsanulok Province; (North): Uttaradit Province. — MYANMAR. — CHINA (South). — VIETNAM. — INDIA (North-East). — BANGLADESH. — BHUTAN. — Forest understoreys on slopes and hills; (200) 900–1,300 m altitude.

Culm size: Height 15–20 (25?) m, diameter 2.5–4 cm.

Descriptions:

(1) "… culms solitary. Rhizomes elongated; pachymorph. Culms erect, or leaning; 1500–2000 cm long; 30–35 mm diam.; woody. Culm-internodes terete; hollow; 20–23 cm long; dark green, or glaucous. Lateral branches dendroid. Culm-sheaths pubescent; with appressed hairs; with dark brown hairs; truncate at apex; auriculate; ciliate on shoulders. Culm-sheath ligule dentate. Culm-sheath blade triangular; as wide as sheath at base; acuminate. Leaf-sheaths puberulous. Ligule an eciliate membrane. Leaf-blade base asymmetrical; with a brief petiole-like connection to sheath; petiole 0.7–1.3 cm long. Leaf-blades lanceolate, or oblong; 10–20 cm long; 25–60 mm wide. Leaf-blade venation with 14–22 secondary veins; with distinct cross veins. Leaf-blade surface smooth. Leaf-blade apex attenuate. … [flowers and seeds described]." — Kew GrassBase [#1335].

(2) "Rhizome neck to 1 m, to 1 cm in diam. Culms 5–10 m, 1.2–2 cm in diam.; internodes straight, 13–20 cm or longer, initially glaucous, with white powdery ring below node; nodes with level supra-nodal ridge and sheath scar; intranode ca. 3 mm; branching from ca. 5th node up. Branches ca. 50 cm. Culm sheaths broadly triangular, rather thin, proximally dark brown strigose, apex shallowly concave or truncate; auricles absent or very small; oral setae erect or curved; ligule short, ciliate, denticulate; blade narrowly triangular, striate, with some transverse veinlets. Leaf sheaths initially white powdery to slightly pubescent, glabrescent; auricles inconspicuous or absent; oral setae few or absent; ligule short; petiole 3–6 mm, glabrous; blade oblong-lanceolate, ca. 12.5 × 2–6.8 cm, glabrous, base subrounded to cuneate, asymmetrical, apex acuminate with twisted strigose tip. … [flowers and seeds described]." — Flora of China [#1303].

(3) A. Teerawatananon & al., Studies in the recent new genus record Pseudostachyum (Poaceae: Bambusoideae) from Thailand: notes on its taxonomy, distribution and habitat, Nordic J. Bot. 32, 2013: p. 51-54 [#1202].

Images: Line drawing in J. S. Gamble, Bambuseae Brit. India, 1896: pl. 85 [#1230]; Flora of China [#1303]; A. Teerawatananon & al., l.c., 2013 [#1202]. Photo of the type specimen at Kew Herbarium (flowering branch) [#1333].

Characteristics: Rhizome pachymorph, with a long neck, up to 3 m long, to 1 cm in diameter. Culms pendulous. Culm-internodes thin-walled. Branches many, subequal, thin, about 50 cm long. Culm-leaf sheath with appressed dark brown hairs, apically truncate. Culm-leaf auricles inconspicuous. Culm-leaf blade triangular.

Uses: Culms for basketry and mats.