Six new species of Melocalamus ( Gramineae : Bambusoideae ) from Vietnam

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INTRODUCTION
Bamboos have long been closely related to the life of Vietnam's people for thousands of years and bamboo clumps are considered as symbols of culture in rural areas. They are used for numerous purposes: house and bridge construction, piping, household implements and tools, food (fresh and dried bamboo shoots), fuel, etc.
Out of the c. 1 200 bamboo species, Vietnam may have up to more than 200, as many as or more than the number found in the nearby Yunnan province of China, because additional new species may be expected from the west and south (Nguyen 2006).  (Ohrnberger 1999). Li & Stapleton (2006) Seethalakshmi & Kumar (1998).

MATERIAL AND METHODS
With support from the research projects 'Conservation of Forest Plant Genetic Resources, period 2001-2005' and 'Species Diversity and ex situ Conservation of Some Bamboos in Vietnam' (2003-2005 by IPGRI, field surveys have been conducted all over Vietnam including provinces of northern, central and southern Vietnam. Based on the morphology of clumps, stems, leaves, sheaths, flowers and fruits and the publications by Gamble (1896), McClure (1936 Melocalamus to Dinochloa), Dransfield (1981), Hui & Hsueh (1992), Seethalakshmi & Kumar (1998), Pham (1999), Li (2000), Guo & Li (2001), Li & Stapleton (2006), six new species of Melocalamus were recognized by Nguyen & Tran (2006, in Vietnamese), which are here formally named and described. Culms up to 20 m long; 1-1.5 cm diam, flexuose, internodes 35 -40 cm long, hollow stems and branches. Young stems covered with sparse, appressed, stiff hairs; nodes with 1 cm high, 2 cm wide buds and a white, powdery 1.5 cm high circle under the node. There is a large branch as the main stem and some small branches. Culm sheaths purple, swollen at base, lower base 9-9.5 cm wide, 13-15 cm high; upper base 3.5-4 cm wide. Outer surface covered with a thick, white, powdery layer and smooth veins. Blade triangular, 11-13 by 2.5-3 cm, green as normal leaves and deflexed or reflexed; base concave, apex with long, acute tip. Auricles 1.5-2 by 0.4-0.5 cm, curved outwards; two auricles almost embraced the shoot. Leaf wedge-shaped, 16-17 by 1.5-8 cm, base obtuse or rounded, veins 5 or 6 pairs. Auricles short, with short hairs. Leaf sheaths with hairs at margins. Pseudopetiole 0.2 cm long, covered with sparse, smooth pubescence. Flowering branches flexuose, covered with dense and smooth pubescence up to the tip, usually flat and slightly concave on one side. Pseudospikelets small, with a very short pedicel, 2.5-3 by 2.5-3 mm, each with 2 opposite complete florets and one sterile in the middle; glumes 2 or 3, the largest 1.8-2 by 1. Culms more than 10 m long, 1.8-2.3 cm diam, culm wall 0.8 cm, internodes 80-85 cm long. Young stems green, old stems grey green, nodes covered with appressed, white hairs. One large branch reiterating the main stem and some small branches on remaining culm nodes. Stems hollow as Schizostachyum. This feature can be used for distinguishing this species from other Melocalamus species. Culm sheaths stiff, embraced the culm; outer surface covered with smooth, fugacious, black hairs. Lower base 22-30 by 15-18 cm; upper base 9-12 cm wide. Blade triangular, 13-19 by 4.5-6.5 cm. Auricles rounded, 4-4.5 by 0.5-0.6 cm, serrate, with 2 cm long stiff hairs. Ligules rounded according to sheath base, with sparse, 1.2 cm long hairs. Leaf blades 30-36 by 6-7 cm, base obtuse, oblique. Veins 10-12 pairs. Ligules 0.2 cm high, with sparse stiff hairs. Auricles c. 0.2 by 0.8 cm, undulated, with sparse stiff 2.5 cm long hairs. Pseudopetiole 0.3 cm long. Flowering branches flexuose, covered with dense and smooth pubescence up to the tip, usually flat and slightly concave on one side. Pseudospikelets small, with a very short pedicel, 2.5-3 by 2.5-3 mm, each with 2 complete florets and one sterile in the middle. Glumes 2 or 3, outer surface covered with smooth hairs, margins with short standing hairs; the largest c. 2 by 2 mm, base concave, top slightly truncate; lateral veins 5, midrib conspicuous, apically swollen at tip. Lemma 2-2.5 by 2-2.5 mm, outer surface with dense pubescence; margin thin, tomentose; veins 5, midrib conspicuous, apically swollen at tip. Palea keeled, not clasping whole styles and stamens, 2-2.5 by 1.8-2 mm; outer surface covered with sparse pubescence, margins with long hairs. Lodicules 3, two of them ovoid, 1-1.2 by 1 mm, margins with long hairs; the last one oblong. Stamens 6, c.  Flowering branches flexuose, covered with dense and smooth pubescence up to the tip, usually flat and slightly concave on one side. Pseudospikelets small, with a very short pedicel, c. 3 by 2 -2.5 mm, each with 2 complete florets and one sterile in the middle. Glumes 2 or 3, outer surface covered with dense, smooth hairs; margins with long hairs; the biggest 2 -2.2 by 2-2.2 mm; lateral veins 5, midrib conspicuous, apically swollen at tip. Lemma 3.5 -4 by 3 -3.5 mm, outer surface with dense pubescence; margins with long pubescence; veins 5, midrib conspicuous, apically swollen at tip. Palea keeled, crasping whole styles and stamens, c. 3 by 2.5 -3 mm, top concave; outer surface covered with dense pubescence, margins with long hairs. Lodicules 3, two of them ovoid, c. 0.5 by 0.5 mm, margins with long hairs; the last one lanceolate, up to 1.5 mm long, margin with very long hairs. Stamens c. 1 by 0.5 mm. Styles large, flat, short, margins with smooth and long hairs. Stigmas 2, flat, on the top of styles, tomentose. Ovary ovoid, velutinous. Fruits fleshy, globose.

Melocalamus
Distribution -The species occurs along the Truong Son road from Song Thanh Nature Reserve (Quang Nam Province), Ngoc Linh (Kon Tum), Ba Na (Da Nang), Bach Ma National Park (Thua Thien-Hue) to Phong Nha-Ke Bang National Park and Deo Gio Pass (Quang Binh).
Habitat -This species occurs at 180-1057 m a.s.l. altitude. Flowers, fruits and seedlings were collected in August 2005.