Gigantochloa glabrata N. H. Xia & Y. Zeng ex D. Z. Li & Z. C. Xu, 2021

Xu, Zu-Chang, Liu, Jing-Xia & Li, De-Zhu, 2021, Gigantochloa glabrata (Poaceae, Bambusoideae), a new bamboo species from Yunnan, China, PhytoKeys 171, pp. 37-45 : 37

Gigantochloa glabrata N. H. Xia & Y. Zeng ex D. Z. Li & Z. C. Xu sp. nov. “少毛巨竹” (Shao Mao Ju Zhu) Figures 1 , 2

Gigantochloa glabrata N. H. Xia & Y. Zeng in Y. Zeng Taxonomic Studies of Gigantochloa in China 36. 2014. nom. nud. . ‘Type’: CHINA. Yunnan: Xishuangbanna Tropical Botanical Garden (XTBG), Menglun, cultivated, 31 Aug 2012, Y Zeng 17 ( ‘holotype’, IBSC).

Gigantochloa albociliata = Gigantochloa albociliata auct. non (Munro) Kurz: C. J. Hsueh & J. L. Sun in Keng f. & Z. P. Wang, Fl. Reippubl. Poppularis. Sin. 9(1): 198. pl. 50, 1-11. 1996; D. Z. Li & Stapleton in Z. Y. Wu, P. H. Raven & D. Y. Hong, Fl. China 22: 47. 2006; L. B. Zhang in C. Y. Wu, P. H. Raven & D. Y. Hong, Fl. China Illustr. 22: 46. fig. 46:1-11, 2007.

Diagnosis.

Gigantochloa glabrata has erect culm sheath blade and the culm sheath covered with sparsely deciduous setae, with truncate apex. It is morphologically similar to G. albociliata and G. levis , but can be easily distinguished from them by having erect blades; culm sheath ligule 4-6 mm high, truncate, denticulate; a ring of white tomentum on the intranode and below the node (Table 1 ).

Type.

China. Yunnan: Xishuangbanna Tropical Botanical Garden (XTBG), Menglun, Mengla, 101.2522°E, 21.9303°N, 514 m alt., introduction no. 00.1978.0594, 22 August 2019, Xuzc2019041 (holotype, KUN!).

Description.

Sympodial bamboo, loosely tufted. Rhizomes pachymorph. Culms erect, lower nodes with verticillate aerial roots, apically pendulous, 9-14 m tall, 5-9 cm in diameter; internodes terete, greyish-green, yellow striped, 20-40 cm long, wall 7-12 mm thick, culm surface initially densely covered with white to brown hairs when young and glabrous or patchy smudge later; nodes inconspicuous, internode 7-10 mm tall, with a ring of white tomentum at the intranode and below the node. Culm sheaths deciduous, leathery, adaxially glabrous, abaxially sparsely hispidous with brown to black deciduous hairs, strigose, 20-28 cm long, hay colour, with truncate apex; auricles narrowly falcate, 7-10 mm wide, 1-2 mm tall; ligules 4-6 mm tall, denticulate; blades triangular, erect, 4-7 cm long, 1/2 as wide as the apex of culm sheaths. Bud ovate, branching high, from 3-4 m above ground, branches several, one dominant. Foliage leaves 8-12 per ultimate branchlet, usually 10; sheaths initially sparsely white hairy and later glabrous, keeled; auricles inconspicuous; ligules ca. 2 mm tall, entire or split; collar with external ligule; blades lanceolate, 10-28 (-40) cm × 2-4 cm, base cuneate, glabrous, margins serrulate, secondary veins 7-11 pairs, pseudopetioles 2-4 mm long.

Inflorescence iterauctant; flowering branches pendulous, leafless, with clusters of 4-8 (-20) large fertile pseudospikelets mixed with a few small sterile ones at each node, subtended by glumaceous bracts; internodes 2-10 cm long, covered with white deciduous hairs. Pseudospikelets narrowly ovate, light green, 12-18 mm long, 2-3 mm wide; fertile ones sessile, perfect fertile florets 2-4, with diminished florets at the apex; disarticulated above glumes, but not between florets; rhachilla internodes compressed between florets. Glumes 2-3, broadly ovate, persistent, veined, 5-9 mm long, 4-6 mm wide, margins ciliated at upper half. Fertile lemma lanceolate, 14-16 mm long, chartaceous, apex mucronate, glabrous abaxially, margins ciliated; palea oblanceolate, 2-keeled, equal length to lemma, keels and margins long ciliated; lodicules absent; anthers 6, 8-10 mm long, yellow, with a finely-toothed gradual apical tip 0.5-1 mm long, filaments united into a firm tube, 6-10 mm long; stigmas one, purple, plumose, ovary umbonate, pubescent apically. Caryopsis unknown.

Phenology.

New shoots May to August.

Distribution and habitat.

Gigantochloa glabrata is cultivated at the Bamboo Garden, XTBG, introduced from Mengyang Town, Jinghong City, Yunnan, China in 1978 with XTBG accession no. 00.1978.0594. However, we could not find it over a field survey in Mengyang area in 2019.

Etymology.

The specific epithet refers to the culm sheath covered with sparsely deciduous hairs.

Additional specimens examined.

China. Yunnan: Menghai Country, Daluo Town, Manka, 22 October 1978, J. L. Sun 18070 (HITBC!); China. Yunnan: Mengla Country, Menglun Town, Bamboo Garden, XTBG, cultivated, 31 August 2012, Y. Zeng 17 (IBSC!, with no flowering branches); ibid., 1 August 2007, K. H. He (何开红) C130051 (HITBC!, HITBC0024167, flowering branches); ibid., 30 May 2020, Xuzc2020001 (KUN!). All collections cited here (with the exception of J. L. Sun 18070) come from the same bamboo clump that was introduced to XTBG with the accession no. 00.1978.0594 in 1978 from Mengyang.

Figures

Figure 1. Gigantochloa glabrata N. H. Xia & Y. Zeng ex D. Z. Li & Z. C. Xu A leaf branch B flowering branch C culm sheath D leaf ligule E pseudospikelet F inflorescence G lemma H anthers I pistil J palea. Drawn from the type specimen and pictures by Yi-Fan Li. Scale bars: 2 cm (A-C); 8 mm (G-J); 4 mm (D-F).

Figure 2. Gigantochloa glabrata N. H. Xia & Y. Zeng ex D. Z. Li & Z. C. Xu A-C culm D, F culm sheath E, I leaf G flower branches H, J pseudospikelet K, L glume M lemma (l), palea (p), ovary (o), stamens (st). Scale bars: 1 m (A); 3 cm (C); 1 cm (E, H).