NEW SPECIES OF SCHIZOSTACHYUM ( POACEAE – BAMBUSOIDEAE ) FROM THE ANDAMAN ISLANDS , INDIA

During the revisionary studies on Indian bamboos the authors could undertake a survey in the Andaman Islands. Five species of bamboos, namely Bambusa atra, Dinochloa andamanica, Gigantochloa andamanica, Bambusa schizostachyoides, and Schizostachyum rogersii have so far been reported from the Andaman Islands (Munro, 1868; Gamble, 1896; Brandis, 1906; Parkinson, 1921). As a result of exploring different parts of the is lands two interesting bamboos were collected. Critical examination revealed that they belonged to the genus Schizostachyum Nees and hitherto undescribed. The genus Schizostachyum was described by Nees in 1829 based on Schizostachyum blumei. This genus is represented by about 45–50 species distributed in tropical and subtropical Asia from southern China throughout the Malaysian region, extending to the Pacific islands with the majority of species in Malaysia (Dransfield, 1983, 2000; Ohrnberger, 1999; Wong, 1995). The genus is characterised by sympodial rhizomes; erect or straggling thin-walled culms; many branches of the same length arising from the node; indeterminate inflores­ cence; absence of glumes in the spikelets; presence of lodicules; slender ovary with long, glabrous stiff style which is hollow around a central strand of tissue; anthers usually with blunt apex. The bamboos collected from the Andaman Islands have straggling culms and are similar to Schizostachyum gracile (Munro) Holttum in certain characters but differ in several other characters. They belong to the species of Schizostachyum Nees which are here described as new.


INTRODUCTION
During the revisionary studies on Indian bamboos the authors could undertake a survey in the Andaman Islands.Five species of bamboos, namely Bambusa atra, Dinochloa andamanica, Gigantochloa andamanica, Bambusa schizostachyoides, and Schizostachyum rogersii have so far been reported from the Andaman Islands (Munro, 1868;Gamble, 1896;Brandis, 1906;Parkinson, 1921).As a result of exploring different parts of the is lands two interesting bamboos were collected.Critical examination revealed that they belonged to the genus Schizostachyum Nees and hitherto undescribed.
The genus Schizostachyum was described by Nees in 1829 based on Schizostachyum blumei.This genus is represented by about 45 -50 species distributed in tropical and subtropical Asia from southern China throughout the Malaysian region, extending to the Pacific islands with the majority of species in Malaysia (Dransfield, 1983(Dransfield, , 2000;;Ohrnberger, 1999;Wong, 1995).
The genus is characterised by sympodial rhizomes; erect or straggling thin-walled culms; many branches of the same length arising from the node; indeterminate inflores cence; absence of glumes in the spikelets; presence of lodicules; slender ovary with long, glabrous stiff style which is hollow around a central strand of tissue; anthers usually with blunt apex.The bamboos collected from the Andaman Islands have straggling culms and are similar to Schizostachyum gracile (Munro) Holttum in certain characters but differ in several other characters.They belong to the species of Schizostachyum Nees which are here described as new.
Flowering & fruiting -Flowering occurs irregularly throughout the year.Etymology -This species is named after the collection locality, Andaman Islands, which is a treasure house of rare and endemic plant species.
Note -Schizostachyum andamanicum is similar to S. gracile (Munro) Holttum in general appearance and culm sheath structure, but it differs from the latter in having a highly straggling culm, short internodes (up to 20 cm), a well-marked nodal line with a spongy ring, short anthers with obtuse apex and a fringe of fine hairs, unequal stigma and caryopsis with a slightly bent beak (Table 1).
Straggling sympodial bamboo, culms up to 5 m tall, sometimes arching over neighbouring trees.Internodes up to 40-45 cm long, hollow, thin-walled, 2-2.5 cm diam., pale green with brownish hairs when young, becoming dull green and glabrous with white powdery below the nodes.Branch complements typically a cluster of slender subequal branches.Young shoots pale orange red.Culm sheaths 15-20 cm long, 9-14 cm wide at the base, rigid, orange red with golden brown to dark brown hairs.Auricle conspicuous up to 4 mm high with long bristles, tip coiled up to 2.5 -3 cm.Blade 8-12 cm long, 2.5 cm wide near the base, brownish orange, rigid, conical, outer surface glabrous, inner surface with silky white hairs (up to 9 mm), base slightly rounded, 1.6 -1.8 cm wide at junction with the sheath, apex acuminate, from the inner side of the blade numerous silky white hairs originated behind the ligule.Ligule short, up to 4 mm long, margin wavy.Leaves linear lanceolate, base broadly attenuate, glabrous on both surfaces.Leaf blade 22-34 by 3.5-5 cm.Leaf sheath with appressed white hairs, hairs caducous.Auricle up to 2 mm long, bearing white bristles.Inflorescence indeterminate, terminating leafy branches.Spikelets arranged in a group of semiverticillate clusters at each node, thin, 1.2-1.3cm long, 2flowered, consisting of a sterile and fertile floret and a rachilla extension of 7-8 mm long, bearing a rudimentary floret (up to 2 mm long).Lemma 7 by 4 mm.Palea 8-9 by 5-6 mm, glabrous, apex fringed with fine hairs.Lodicules 3, equal up to 3 by 2 mm, ovate, apex acuminate, margin serrate.Stamens 6. Anthers up to 5 mm long, apex rounded.Filaments free.Ovary tubular, glabrous, 9 mm long.Style glabrous with well-marked stigmatic base, bearing 3 short stigmas at apex.Stigma equal, pinkish and highly plumose.Caryopsis 15 -18 by 2-6 mm, ovoid, rounded basal part an acute tip with a long beak, surface with angular projections, glabrous.Ecology -Growing near the ecotone of moist deciduous forest at an altitude of 50-250 m.
Flowering & fruiting -Flowering occurs irregularly throughout the year.Etymology -This species is named after the type locality, Kalpong.Notes -1.Schizostachyum kalpongianum is similar to S. gracile (Munro) Holttum in appearance and nature of culm sheath etc. but it is distinct from the latter in having a straggling culm and long internodes (up to 45 cm), characteristic features of culm sheath such as ligule, blade and caryopsis oblong with angular projections (Table 1).
2. Schizostachyum kalpongianum is also closely related to S. andamanicum in ap pearance but differs in having a less straggling culm habit, large culms with long internodes (up to 45 cm), conical blade with silky white to golden brown hairs on the inner surface, a fringe of silky white hairs in between the blade juncture and ligule, equal sized stigma and lodicule, caryopsis with angular projections and a straight beak.