Pleioblastus triangulata (Hsueh & T.P.Yi) N.H.Xia, Y.H.Tong & Z.Y.Niu

Niu, Zheng-Yang, Tong, Yi-Hua & Xia, Nian-He, 2021, Pleioblastus triangulata (Poaceae: Bambusoideae), a new combination for Indosasa triangulata based on morphological and molecular evidence, Phytotaxa 527 (4), pp. 275-283 : 278-281

Pleioblastus triangulata (Hsueh & T.P.Yi) N.H.Xia, Y.H.Tong & Z.Y.Niu , comb. nov. Figs. 1 & 2

Basionym: Indosasa triangulata Hsueh & Yi (1983: 41) ; Institutum Botanicum Kunmingense Academiae Sinicae (1984: 2165); Southwestern Forestry College & Forestry Department of Yunnan Province (1991: 1484); Yi et al. (2008: 246); Yang et al. (2019: 438, excl. figures); Yi et al (2021: 439).

Arundinaria triangulata (Hsueh & T.P.Yi) C.S.Chao & G.Y.Yang in Yang & Chao (1994: 16); Li & Hsueh (2003: 164).

Type: — CHINA. Yunnan: Maguan Xian, Dulong Zhen, Tianbaxin Cun , elev. 1200 m, 21 December 1977, T. P . Yi 77339 (holotype: SIFS) .

Description: —Shrubby or arborescent bamboo. Rhizomes leptomorph; internodes cylindrical, 2–7 cm long, 8–10 mm in diameter, nearly solid; nodes prominent, 4–6 roots at each node; rhizome buds triangular-ovate to ovate, margins brown ciliate. Culms pluricaespitose, erect, 3–6 m tall and 1.0– 2.5 cm in diameter; internodes terete, (10–)25–35(– 40) cm long, basally weakly flattened above branches, initially covered with thick white powder, glabrous; walls 2–5 mm thick; pith lamellate; supranodal ridges not conspicuous; sheath scars prominent, corky, with persistent remains of sheath base. Intranodal region ca 5 mm high, thinly white powdery but darkened by contamination when old, glabrous. Primary buds solitary, triangular-ovate, not sunken into culm, margins densely brown ciliate except base. Branches erect, 3–5 per mid-culm node, subequal, 30–55 cm long, inclined at an angle of 15°–40° with the culm, branch sheaths thinly leathery, shorter than internodes, abaxially glabrous, with unevenly scattered black dots, margins sparsely ciliate. Culm leaf: sheaths long triangular, caducous, thinly leathery, oily, glossy, with pungent smell, 20.5–32.0 × 5–10 cm, 2/3–11/10 as long as internodes, initially yellowish green, brown when dry, abaxial surface glabrous except base with a ring of dense brown setae that are 0.5–7 mm long, with densely dark brown dotted lines between veins, and one black line near the margin of each side of sheath apex, margins sparsely ciliate; auricles absent or present, falcate and densely pubescent when present; oral setae erect, radiate, rigid, scabrid, pale yellow, 3–10 mm long, easily deciduous when old; ligules arcuate to truncate, 1–5 mm tall, entire, with a black band at base, band 1 mm tall, densely pubescent, glabrescent when old; blades reflexed, linear-lanceolate, caducous, 3.0–16.5 × 0.2–0.8 cm, ca 1/2–3/5 as long as sheath, base slightly narrowed, both sides glabrous, margins serrulate. Foliage leaves 2–5 per ultimate branch: sheaths 5.5–7.0 cm long, glabrous, longitudinal ribs conspicuous; auricles and oral setae absent; ligule convex to truncate, 1–2 mm tall, green in vivo, purple when dry, entire, abaxially pubescent, apex ciliate; outer ligule truncate, ca 0.5 mm tall, ca 2 mm wide, entire, apex pubescent; pseudo-petioles 2–5 × 0.5–1.5 mm, glabrous; leaf blades lanceolate, papyraceous, 9–21 × 1.2–2.5 cm, base widely cuneate or truncate, apex acute, glabrous on both surfaces, margins serrulate along both sides, secondary veins 5–7 pairs, transverse veins slightly conspicuous. Inflorescence unknown.

Distribution and habitat: —The species has only been found at its type locality so far. It prefers sunny environments and often grows on mountain slopes near roadsides.

Phenology: —New shoots produced during May to June.

Vernacular names: —Chinese name “K爪Ứ” [wǔ zhǎo zhú], “ẄỨ” [yáng zhú].

Additional specimen examined: —The same locality as type, hillside, in Chinese fir forests, 22°53′58″N, 104°36′36″E, 1220 m, 18 May 2021, Z.Y. Niu NZY040 (IBSC).

Figures

FIGURE 1. Pleioblastus triangulata. A: Habit; B: Branches at mid-culm node; C: Culm bud and internodes with thick white powder; D: New shoot; E: Culm leaf blade; F: Culm leaf ligule, auricles and oral setae; G: Rhizome with a new shoot.All photos by Z.Y.Niu.

FIGURE 2. Pleioblastus triangulata. A: Culm leaf, detached, the arrows showing black lines near margins of culm sheath apex; B: Dark brown dotted lines on culm leaf sheath; C: Culm leaf auricles and oral setae; D: Culm leaf ligule, the arrow showing a black band at base; E: Ultimate leafy branches; F: Foliage leaf inner and outer ligule.All photos by Z.Y.Niu.