Bambusa subtruncata L.C. Chia & H.L. Fung (1981:378)

Qin, Qiao-Mei, Cai, Zhuo-Yu, Ni, Jing-Bo, Tong, Yi-Hua & Xia, Nian-He, 2022, The floral morphology of four Chinese Bambusa species (Poaceae, Bambusoideae) previously described only from vegetative material, PhytoKeys 213, pp. 143-159 : 143

Bambusa subtruncata L.C. Chia & H.L. Fung (1981:378)

Figs 7 , 8

Holotype.

China, Guangdong Province: Guangzhou City, cultivated in South China Botanical Garden, Chinese Academy of Sciences (plants originally from Guangdong, Xinyi, Qingshui mountain), 5 August 1976, Nan-Zhu 2312 (IBSC!).

Epitype (designated here).

China, Guangdong Province: Guangzhou City, cultivated in South China Botanical Garden, Chinese Academy of Sciences, 27 November 2015, Qin & Ni QQM 16 (IBSC!).

Description including flowering material.

Culms 4-5 m tall, 2-2.5 cm diameter, basally nearly straight, apically slightly drooping; internodes 25-33 cm long, glabrous, initially slightly white waxy, green, basal ones typically with yellow stripes; wall ca. 7 mm thick; basal nodes with grey-white sericeous ring-like zones below and above sheath insertion. Primary branch bud broadly ovate, prophyll margins apically ciliate. Branch complement at mid-culm with many branches, central 3 branches dominant, those at culm base without thorny branchlets. Culm leaf sheath initially green with yellow stripes, glabrous or brown hispid especially near margins, apex subtruncate; auricles unequal, larger one about 2.5 times as large as smaller one, moderately to broadly elliptic, ca. 2 cm long, ca. 1.3 cm wide, wrinkled, margins with undulate bristles; ligule 1.5-2 mm high, margin ciliate; blade caducous, erect, triangular to narrowly triangular, base slightly rounded, overlapping with auricles for 6-7 mm, about 3/5 as wide as sheath apex. Foliage leaf sheath glabrous; auricles subovate or tiny, margin with undulate bristles; ligule low, entire; blade linear-lanceolate, 8-15 cm long, 0.9-1.3 cm wide, abaxial surface densely pubescent, adaxial surface glabrous. Pseudospikelets fasciculate at each node of flowering branches, linear, sessile, basally subtended by several bud-bearing bracts at base, 2.5-3 cm long; florets 9-10, middle 4-7 florets fully developed; prophylls ca. 3 mm long, 2-keeled, keels apically sparsely ciliolate; bracts 4-5, lanceolate, 3.5-10.5 mm long, glabrous, adaxial surface puberulent at the upper half, 5-15-veined, apex acute mucronate; rachilla disarticulating between florets, segments compressed, 4-5 mm long, apex ciliolate and flat; no glume; lemma oblong-lanceolate, 12-14 mm long, glabrous, 17-19-veined, apex acute mucronate, calluses ca. 1 mm long, glabrous; palea 12-13 mm long, 2-keeled, keels apically sparsely ciliolate, 4-veined between keels, each side 2-veined, apex slightly puberulent; lodicules 3, apex ciliate, anterior 2 obliquely oblong, 2.5-3.5 mm long, posterior one narrowly obovate, 2.5 mm long; stamens 6, filaments filiform, anthers brown to yellowish, 5-6.5 mm long, apex retuse; ovary obovoid, ca. 1.5 mm long, apex hispidulous, styles 3, 0.5-0.6 mm long, stigmas 3, rarely 4, plumose, 2.5-3 mm long.

Note.

After the comparison of floral characters between this species and a very similar congener, Bambusa tuldoides Munro, the following differences were found: B. subtruncata has a flat rachilla segment apex (versus inflated), 4-5 bracts (versus 2), no glumes (versus usually just 1), an acute lemma apex (versus obtuse) and 2 veins on each side of the palea (versus 4 veins).

Figures

Figure 7. Vegetative morphology and pseudospikelets of B. subtruncata A clump B culms internode C branch complement D primary branch bud E pseudospikelet F culm leaf (abaxial view) G culm leaf (adaxial view) H the distal part of a leafy branch (upper side) I the distal part of a leafy branch (lower side).

Figure 8. Floral morphology of B. subtruncata A pseudospikelet B prophyll (abaxial view) C rachilla segment D empty bract (adaxial view) E empty bract (abaxial view) F lemma (adaxial view) G palea showing margins H back of palea I pistil J lodicules K stamen. Drawn by Ding-Han Cui.