Bambusa rushunii J. B. Ni & Y. H. Tong, 2025

Bambusa rushunii J. B. Ni & Y. H. Tong sp. nov.

Figs 1 View Figure 1 , 2 View Figure 2

Type.

China. • Guangdong Province: Yangjiang City, Yangchun County, Tanshui Town ; 22°4'52.71"N, 111°36'6.80"E; alt. 28 m; 18 September 2023; Jing-Bo Ni et al. NJB-004 (holotype: IBSC!) GoogleMaps .

Diagnosis.

Bambusa rushunii resembles B. gibba McClure and B. dissimulator McClure , but can be easily distinguished from B. gibba by having a thicker culm wall (ca. 1.5 cm vs. 3–5 mm), extremely shortened basal internode present (vs. absent), culm leaf sheath without (vs. with) a protuberance on higher shoulder and dark brown strigose on the central part (vs. glabrous wholly), higher culm leaf ligule (4–8 mm vs. 2–3 mm) and glabrous (vs. abaxially densely pubescent) foliage leaf and is different from B. dissimulator by the extremely shortened basal internode present (vs. absent), nearly truncate or slightly obliquely truncate (vs. asymmetrically convex) culm leaf sheath apex, culm leaf auricle contiguous (vs. not contiguous) with the blade base, culm leaf blade base not narrowed (vs. narrowed), foliage leaf ligule margin ciliate (vs. glabrous) and glabrous (vs. abaxially pubescent) foliage leaf.

Description.

Arborescent bamboo. Rhizome pachymorph, short-necked. Culm 8–10 m tall, 5–7.5 cm in diameter, erect, basal part slightly zigzag, apex slightly pendulous; internode terete, 35–45 cm long, 2 nd and / or 3 rd and / or 4 th internodes usually extremely shortened, only ca. 1 cm long; initially white powdery, glabrous, basal internodes green with many pale yellow stripes, stripes sometimes not inconspicuous; wall ca. 1.5 cm thick; supranodal ridge inconspicuous, sheath scars raised; culm bud round, branches developing from 5 th node upwards, nearly horizontally spreading, branch complements with several branches per node, central 3 dominant, branchlets usually specialised into weak thorns. Culm leaf sheath deciduous, thickly leathery, 30–40 cm long, 9–12 cm wide at apex, 20–32 cm wide at base, with yellow-green stripes, stripes inconspicuous when dry, sparsely dark brown strigose on central part, longitudinal ribs conspicuous when dry, apex nearly truncate or slightly obliquely truncate, without protuberance on shoulder; auricles unequal, oblong to lanceolate, contiguous with the base of blade, slightly wrinkled, margin densely with ca. 8 mm long and curved oral setae; larger auricle 1–2 cm long, 4–6 mm wide, not slanted; smaller auricle 3–8 mm long, 2–5 mm wide; ligule 4–8 mm high, margin serrate, densely with 2–3 mm long cilia; blade erect, narrowly triangular, 10–13 cm long, 5–8 cm wide, 1 / 2–3 / 5 as long as culm sheath, glabrous on both sides, apex involute and acuminate, base slightly extending outwards and joined with auricles, 3 / 5–4 / 5 as wide as sheath apex. Foliage leaves 7–11 per ultimate branchlet, sheath ca. 6 cm long, glabrous; auricles elliptic, ca. 2 mm long, ca. 1 mm wide, oral setae deciduous, ca. 8 mm long; inner ligules ca. 1 mm high, entire, margin ciliate; pseudopetioles ca. 2 mm long, ca. 1 mm wide; blades linear-lanceolate, papyraceous, 15–20 cm long, 1.4–1.7 cm wide, both surfaces glabrous, apex acuminate, base subrounded to cuneate, secondary veins 6 pairs, transverse veins inconspicuous. Pseudospikelets sessile, usually several to many fasciculate at nodes of flowering branches, green when fresh, yellow when dry, linear-lanceolate, 4–6 cm long, 5–8 mm wide, basally subtended by several gemmiferous bracts; prophylls ovate, 3–4 mm long, 2 – keeled, apex densely ciliolate; gemmiferous bracts 1–3, ovate, 4–9 mm long, glabrous, 10–14 - veined, apex acuminate and muronate; florets several to many, apical 1–2 sterile, rachilla segments flat, ca. 4 mm long, puberulous, slightly grooved, apex enlarged, with a ring of white hairs, disarticulating below each floret; glumes 1 or 2, broadly ovate, 5–6 mm long, glabrous, 10–12 - veined, apex acute; lemma lanceolate, ca. 13 mm long, glabrous, 10–12 - veined, apex acute; palea lanceolate, ca. 12 mm long, slightly shorter than lemma, apex acute, abaxially 2 - keeled, keels densely ciliolate at apex, with 6 veins between keels and 4 veins on each side; lodicules 3, subequal, fleshy, white, ca. 2 mm long, margin with long cilia; stamens 6, filaments free, ca. 2 cm long, white; anthers initially green-yellow, later yellow-brown, ca. 5 mm long, apex retuse; ovary obvoid, ca. 1 mm long, apex hispidulous, style short, ca. 0.3 mm long, sparsely hispidulous at base; stigmas 3, 2–3 mm long, slender and plumose. Mature caryopsis fusiform, yellow, ca. 8 mm long.

Phenology.

New culm shoots produced from July to September, flowering in September.

Distribution and habitat.

This new species is found in Yangjiang City, Guangdong Province, China and cultivated in South China Botanical Garden. It usually occurs near villages and streams at elevations of 20– 120 m.

Etymology.

The species epithet honours Mr. Ru-Shun Lin, a retired employee from South China Botanical Garden, Chinese Academy of Sciences, who has made more than 600 living collections of bamboos and contributed a lot to the development of the Bamboo Garden of South China Botanical Garden. Its Chinese name is given as 汝顺坭簕竹 (Pinyin: rǔ shùn ní lè zhú).

Discussion.

In " Flora of China ", the genus Bambusa was further classified into four subgenera: subg. Bambusa , subg. Dendrocalamopsis L. C. Chia & H. L. Fung , subg. Leleba (Rumph. ex Nakai) Keng ex L. C. Chia & H. L. Feng and subg. Lingnania (McClure) L. C. Chia & H. L. Fung ( Xia et al. 2006). Bambusa rushunii possesses typical characteristics of subg. Bambusa , such as the relatively thick culm wall, persistent culm leaf blade with a broad base that is 1 / 2–3 / 4 as wide as sheath apex and the branchlets usually specialised into weak thorns. Thus, it is placed into that subgenus.

Amongst the species of B. subg. Bambusa , B. rushunii is most similar to B. gibba and B. dissimulator in the branchlets of lower branches which are usually specialised into weak thorns and the relatively small culm leaf auricles. The detailed morphological comparison of the three species is shown in Table 1 View Table 1 and the diagnosis section. The most unique morphological character of B. rushunii is the extremely shortened internodes at the culm base. As far as we know, this characteristic also occurs to another species of Bambusa subg. Dendrocalamposis , viz. B. bicicatricata (W. T. Lin) L. C. Chia & H. L. Fung. However , except this character, B. rushunii is very different from B. bicicatricata in many other characters, such as morphology of culm leaves, pseudospikelet length and number of stigmas, since they belong to different subgenera ( Chia et al. 1996; Xia et al. 2006).

Additional specimens examined.

Bambusa rushunii J. B. Ni & Y. H. Tong : China. • Guangdong Province, Guangzhou City, Tianhe District , introduced from the type locality, cultivated in Bamboo Garden of South China National Botanical Garden, 5 September 2024, J. B. Ni 005 (paratype: IBSC) .

Bambusa dissimulator McClure : China. • Guangdong Province, Guangzhou City, Panyu District [Haizhu District], Lingnan University campus (now the campus of Sun Yat-Sen University ), 26 September 1939, F. A. McClure 20861 (K 000854766, image); • ibid., 30 April 1931, H. Fung A- 674 / BG 2348 (A 00023169, image, L 0043812 , image, SYS 00095355 , US 00130308, image, US 00130310, image, US 00130311, image, US 00130312, image); • ibid., 18 November 1929, H. Fung LU 18499 (SYS 00011949, US 00391111, image); • ibid., 30 April 1931, H. Fung LU 19079 (isotypes: CAS 0027955, image, ISC-v- 0000942, image, ISC-v- 0000943, image, K 000854765, image, L 0043812 , image); • ibid., 15 March 1932, H. Fung 20003 (two sheets: SYS 00011892 & SYS 00011893); • ibid., Lingnan University, Primary School , 30 October 1936, H. Fung 20987 (US 0050544, image).

Bambusa dissimulator var. albonodia McClure : China. • Guangdong Province, Guangzhou City , Honam Island [Haizhu District], west end of same island of land, Lingnan University Agriculture workmen’s barracks, 13 December 1937, F. A. McClure 20719 (holotype: two sheets US 00130313 & US 0034812, image); • ibid., Honam Island [Haizhu District], Ng Ts’uen, 18 May 1921, F. A. McClure LU 18552 (two sheets: US 00034813 & US 0034814, image).

Bambusa dissimulator var. hispida McClure : China. • Guangdong Province, Guangzhou City , Panyu District [Haizhu District], growing on edge of small knoll, east. of Lingnan University campus (now the campus of Sun Yat-Sen University), 26 September 1939, F. A. McClure 20861 (holotype US 00130315, image; isotypes A 00023170, image, ISC-v- 0000944, image, K 00854764, image, K 00854766, image, L 0043813 , image, P 00800933, image).

Bambusa gibba McClure : China. • Kiangsi [Guangxi], south of Kanchow [Qinzhou], cultivated in Lingnan University Bamboo Garden (now in the campus of Sun Yat-Sen University), 30 September 1933, H. Fung 20709 (holotype: three sheets US 00065370, US 00065371 & US 00065372, image; isotype: three sheets US 00289540, US 00289541 & US 00289542, image); • ibid., March 1929, F. A. McClure LU 18518 (A 00023177, image, K 000854759, image, L 0043815 , image, L 0043816 , image, P 00800942, image SYS 00095349); • ibid., 23 February 1937, H. Fung 21001 (SYS 00095350, SYS 00095351 ).