Acidosasayixingensis, a New Combination in Acidosasa(Poaceae: Bambusoideae) from China

LAI Guang-hui

(Guangde Forestry Bureau of Anhui Province, Guangde 242200, Anhui, China)

Acidosasayixingensis, a New Combination inAcidosasa(Poaceae: Bambusoideae) from China

LAI Guang-hui

(Guangde Forestry Bureau of Anhui Province, Guangde 242200, Anhui, China)

According to the reliable flowering specimens collected from a population, which was previously identified asPleioblastusyixingensisS. L. Chen et S. Y. Chen, and field investigation in Anhui Bamboo Garden, its floral morphological features, such as the single occurrence of genuine inflorescence, terminal panicle or raceme on branchlet, spikelet pedicelled, and floret bearing 6 stamens, were recognized the first time. These floral characters showed that this species should be moved fromPleioblastusNakai intoAcidosasaC. D. Chu et C. S. Chao, as a new combination, "Yixing Suanzhu" was proposed as its Chinese name, and it was named asAcidosasayixingensis(S. L. Chen et S. Y. Chen) G. H. Lai. The discovery of its flowering plants and floral characters is of importance for the study on origin, dispersal and phylogenies of the monopodial bamboo species.

Bambusoideae;Acidosasa; New combination;Acidosasayixingensis

Yixing Bitter Bamboo (Yixing Kuzhu) was described as new to science and was named asPleioblastusyixingensisS. L. Chen et S. Y. Chen in 1983 with characters of vegetative organs only[1]. Although this species was recognized in the later taxonomical literature[2-8], but no description of floral morphology was given, so that its systematic position, which was put intoPleioblastusNakai orArundinariaMichx. with floret bearing 3 stamens, is fixed until now. In 2008, Yi et al. provided a picture of the inflorescence of this species with two flowering florets[8], which seem to have 4-5 stamens, and its floral morphology not been still described.

This species was introduced from the Bamboo Garden of Nanjing Forestry University into Anhui Bamboo Garden (ABG) in June 1999 and cultivated under No. 99-008. In a long period of time, it has a good clonal propagation and vigorous growth, with more plants in the population. But in recent years, its growth was not as good as before and rarely developed shoot in the spring of 2016. In November 2016, many flower buds sprouted out from some of its plants, and soon began to blossom, which provides a chance of investigating its floral morphology. A field observation showed that its inflorescence occurs singularly, consisting of 5-8 spikelets that contains 3-6 florets with 6 stamens. Obviously, put this species intoPleioblastusNakai is not appropriate, and it should be transferred intoAcidosasaC. D. Chu et C. S. Chao as a new combination.

Acidosasayixingensis(S. L. Chen et S. Y. Chen) G. H. Lai, comb. nov. Fig. 1 宜兴酸竹

PleioblastusyixingensisS. L. Chen et S. Y. Chen, Acta Phytotax. Sin. 21 (4): 411, f. 9. 1983. Type: China, Zhejiang Province, Hangzhou City, Hangzhou Botanical Garden, 1978-05-13, Chen Shaoyun & Meng Lanhua 78027 (holotype, HHBG).

Fig.1 Acidosasa yixingensis (S. L. Chen et S. Y. Chen) G. H. Lai. A-B. Bamboo shoots in a population cultivated at ABG (No. 99-008) in May 2006, showing normal vegetative growth at that time; C. Flowering plants in the same population in December 2016; D-E. Flowering branches, showing a panicle or a raceme terminal on branchlet; F. Spikelets and their slender pedicels; G. Bracts at the base of inflorescence; H. The first and the second glume; I. A part of floret, showing 6 stamens with yellowish anther; J. A node of spikelet rachilla, showing slightly grooved side; K. Lemma in dorsal view; L. Palea in dorsal view; M. Palea in ventral view; N. Lodicules; O. Ovary and style with 3 plumose stigmas.

Panicle or raceme terminal on branchlet, bearing 5-8 spikelets, 6.5-12 cm long, basally subtended by a deciduous sheath; pedicel 3-noded, 1.5-4.3 cm long, glabrous, together with the base of the inferior spikelets tightly clothed with upward gradually amplifying, imbricate 4-6 bracts, of which the largest 22-25 mm long, with obvious longitudinal veins and deciduous powder, back glabrous, margin ciliate, mouth not auriculate but with bristles at two shoulders, apex with lanceolate or narrowly lanceolate reduced leaf; inflorescence axis slender, usually curved, with 0.6-1.5 cm long internodes, purpurate or green, usually glabrous, densely pruinous. Spikelets more robust, more or less compressed, (1.6) 3-6 (7.6) cm long, 2-4.5 mm wide, (3) 5-7 (9)-flowered; pedicel slender, more or less curved, 0.5-1.3 cm long, green or purpurate, densely pruinous, hispidulous sparsely subglabrous at the superior half part; rachilla 2-6 mm long, more robust, the upper part slightly thicker than the lower part, flattened, slightly grooved along the branch-bearing side, greenish, glabrous, pruinous; glumes 2 (rarely 3), primarily light green sometimes purpurate, immediately marcescent, the first smaller, 4-6 mm long, apex obtuse, back 1-porcate and 4-6-nerved, pruinous, the second bigger, 5-10 mm long, apex mucronate or obtuse with short cilia, back 1-porcate and 6-10-nerved, glabrous, the third similar to lemma but shorter than it; lemma ovate-lanceolate, chartaceous, primarily light green, later 2/3 part of inferior green but 1/3 part of superior slightly purpurate, 8-14 mm long, 11-15-nerved, slightly tessellated, glabrous, densely pruinous, apex long-acuminate; palea thin-chartaceous, light green, slightly purpurate at the apex, slightly longer than or about as long as lemma, 8-14.5 mm long, back flat or slightly concave, slightly 2-keeled, apex obtuse, integer and not bifid, margin ciliate above the middle; lodicules 3, membranaceous, band-shaped or narrowly ovate, ca. 4 mm long, yellowish at the inferior half part and purplish at the superior half part, margin white-ciliate; stamens 6; anthers initially yellowish-green, later yellowish, band-shaped, 6-9 mm long, apex obtuse or slighty concave, base hastate; filaments separated, white, 7-10 mm long, glabrous; ovary flask-shaped, slender and thiner, slightly yellowish, 1.5-2 mm long, base 1.5 mm wide, glabrous; style 1, white, 2-2.5 mm long; stigmas 3, plumose, 4-5 mm long, infrior half part white, superior half part brownish. Fruit not seen. Flowering in December.

China, Anhui Province, Guangde County, Taozhou Town, Hengshan National Forest Park, Anhui Bamboo Garden, G. H. Lai 16012 (GDFI*)

In the mid-subtropical to north subtropical zone of eastern China, it was only known that the species inSasasubgen.Sasamorpha(Nakai) C. H. Hu, which are generally considered to belong to more evolutionary taxa[9-10]for their distribution at a special habitat with an altitude of more than 1 000 m and specialization to small shrubby bamboo with 1 branch nearly as thick as culm at each node, have a semelauctant inflorescence and all the florets with six stamens[11]. But the species inAcidosasaC. D. Chu et C. S. Chao with 3 thinner branches at each node of culm, which are arborescent and are distributed at humid habitat in southern China, has been proposed to be phylogenetically more primitive thanSasaMakino et Shibata in the original publication[12].Acidosasayixingensis(S. L. Chen et S. Y. Chen) G. H. Lai, a stenochoric species endemic to southern Jiangsu Province, is restrictively distributed in the very narrow region of north subtropical zone, eastern China. This species originated possibly during northward migration of the congeneric plants for an adaptation to the local environment in a warm period of geological history. A discovery of its flowering plants and floral characters is of important value for studys on origin, dispersal and phylogenesis of the scattered bamboo species.

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国产竹亚科酸竹属一新组合——宜兴酸竹

赖广辉

(安徽省广德县林业局， 广德 242200)

根据采自安徽竹类植物园中宜兴苦竹的可靠花枝标本和现场调查记载表明，该竹种系单次发生的真花序，圆锥或总状花序顶生于小枝，小穗具柄，小花有6枚雄蕊，显然其花部形态与酸竹属高度吻合，故将其从原隶属的苦竹属中移出而转入该属，同时在作出新组合的基础上，重新拟定其中文名称为宜兴酸竹。本种开花植株及花部形态特征的发现，对研究散生竹的起源、散布和系统发育均具有重要价值。

竹亚科；酸竹属；新组合；宜兴酸竹

s: The International Science and Technology Cooperation Project of Anhui Province (02088011), and the Research Project of Forestry Department of Anhui Province (2005-12-01)

Author: LAI Guang-hui, senior engineer, research interests: taxonomy of scattered bamboos. E-mail: lybamb@21cn.com

*GDFI=Herbarium of Guangde Forestry Institute, Anhui Province, China