Bambusa rigida
Bambusa rigida Keng & Keng f., J. Wash. Acad. Sci. 36, 1946: 81.
Synonym: Bambusa stipitata W. T. Lin.
Thai name: ไผ่ริกิดา (phai rikida).
Chinese name: 硬头黄竹 (yìng tóu huáng zhú).
Distribution: CHINA (South): Sichuan, usually cultivated along riversides and around villages of the Sichuan basin; also cultivated in Yunnan.
Culm size: Height 5–9 (12) m, diameter 2–5 (6) cm.
Descriptions:
(1) "Culms 5–12 m, 2–6 cm in diam., basally upright, apically slightly arched; internodes 30–45 cm, initially thinly white powdery, glabrous; wall 1–1.5 cm thick; nodes slightly prominent, sometimes basal node with a ring of gray-white silky hairs above sheath scar; branching from basal or 2nd node up. Branches several to many, clustered, central dominant, 4–6 mm in diam. Culm sheaths deciduous, leathery, basally stiffly deciduously dull brown strigose on inner margin, apex slanted outward and slightly asymmetrical, broadly arched; auricles deep brown, unequal, slightly wrinkled; larger auricle usually ovate, ca. 2.5 × 1.5 cm, those on upper culms nearly oblong or lanceolate; smaller auricle ovate or suborbicular, ca. 2/3 size of larger one; oral setae ca. 1 cm, undulate; ligule 2.5–3 mm, laciniate, fringed; blade deciduous, erect, nearly symmetrical, ovate-triangular to ovate-lanceolate, base rounded and extending outward to join auricles for 3–4 mm, nearly 2/5 width of sheath apex, abaxially very sparsely stiffly brown hairy, adaxially densely stiffly brown hairy near base, distally scabrid, apex acuminate, apiculate. Leaf blade linear-lanceolate, 7.5–18 × 1–2 cm, abaxially densely pubescent, adaxially glabrous or sparsely hairy near base. … [flowers described] … Mature caryopsis unknown." — Flora of China, accessed 19 Oct. 2020 [#1303].
(2) Kew GrassBase [#1335].
Images: Line drawing in Flora of China 1, 2 [#1303].
Bambusa cf. rigida
Distribution: THAILAND: introduced, in cultivation, rare.
Specimen: BS-0518 [C4] [N2] [S4] (living plants), received from cultivated stock as "Bambusa rigida" from Hawaii, USA, Aug. 2010; it was said that the plant was originally obtained from Yunnan, China.
Characteristics: Habit tight caespitose. Rhizome pachymorph, short-necked. Culms straight, erect, vertical or somewhat inclined, slightly bending above, to about 9 m tall. Young shoots [not yet observed in detail], emerge from late March to September. Culm-internodes terete, (37) 50–60 (65) cm long, mid-green, covered thinly with white long-lasting farina, thus appearing bluish, initially scantily scattered with short rigid white hairs, becoming scaberulous with age; diameter to 4 cm; thick-walled. Culm-nodes glabrous, flat; sheath scar marginally protruding 1 mm; supranodal line obscure, without a ridge, 5–7 mm above the nodal line; with a white farinose ring below the sheath scar when young; aerial roots none. Branch-buds solitary, subrotund with a pointed apex, the first 5–8 nodes without a bud. Branches several, slender, the central one usually slightly dominant, thin and subequal on the upper culm, the lower culm usually unbranched; branching intravaginal; rebranching. Culm-leaves deciduous. Culm-leaf sheaths 24 cm wide at the base, 23 cm long (on culms of 4 cm in diameter), shorter than the internode, usually 1/3 as long as the internode or a little shorter on the lower and mid-culm, about 1/2 as long as the internode on the basal culm, coriaceous, rigid, light green to light or mid-brownish when young, light straw-colored when dry, scattered with caducous short light-brownish soft hairs, densely towards the base, glabrous towards the apex, not farinose; margins eciliate; apex rounded, asymmetrical. Culm-leaf auricles unequal, not slanted, not wrinkled, mid-brown to dark brown and glossy when young, connection with the blade ca. 2–3 mm wide, the larger auricle narrowly oblong, about 22 × 4 mm, the smaller one oblong, about 10 × 4 mm; both with undulate bristles, ca. 5(?) mm long, white when young; auricles of the culm-leaves in thin culms or on the upper culm usually lobe-like protruding (6 × 1.5 mm) and not or loosely connected with the margin of the sheath apex, but narrowly (0.5–1 mm) and persistently connected with the blade base edge. Culm-leaf ligule 1–1.5 mm high, denticulate or ciliolate. Culm-leaf blades thickly papery, usually persistent, occasionally caducous, erect, mid-brown, early dried and fading to a light straw color, abaxially glabrous, broad triangular with rounded basal edges on the lower and mid-culm, lanceolate on the upper culm, nearly as long as a sheath on the mid-culm, 8 cm wide near the base, 21 cm long; margins distally convolute; apex long attenuate. Foliage-leaves 5–7 (13) per branchlet. Foliage-leaf sheaths green when young, straw-colored when dry, glabrous; margins eciliate. Foliage-leaf auricles protruding lobes, 2–3 mm long, with about 10 spreading pale 8–10 mm long bristles. Foliage-leaf ligule inconspicuous, less than 0.5 mm high, entire; outer ligule a rounded rim, margin entire. Foliage-leaf blades small, 12–19 × 1.5–2 (2.3) cm, lanceolate to linear-lanceolate, glabrous and almost glossy mid-green to dark green above, puberulous and dull green beneath; base unequally rounded to cuneate; apex attenuate; margins antrorsely scabrous; midrib proximally slightly prominent, light green; pseudopetiole 1–3 mm long. Flowers and seeds are unknown.
Uses: Culms for light construction; plants as garden ornamentals, for hedges and screening.
Cultivation requirements: Grows in part shade to full sun, sandy loam to clay loam, normal moisture-retentive to moist soil with good drainage. Tolerates wind.
Photos in Quindembo; BambooWeb.info [#1340].
Comments: A main key character of Bambusa rigida, "culm sheath blade nearly 1/2 width of sheath apex or narrower" (Flora of China, accessed 1 Jan. 2018 [#1303]) does not match with BS-0518, in which the blade base in mature plants is 3/4 as wide as the sheath apex. All checked vegetative characteristics of BS-0518 are more consistent with Bambusa textilis than B. rigida.
Bambusa cf. rigida (BS-0518): Young culm