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植物研究雑誌 J. Jpn. Bot. 72: 297-300(1997) AN ew Species of Scirpus Ser. Actaeogeton (Cyperaceae) from Japan Katsutoshi ARAIl) and Futoshi MIYA MOTO Faculty of Agriculture，To kyo University of Agriculture， Sakuragaokaト1-1，Setagaya-ku，To kyo，1 56 JAPAN (Received on March 6，1 997) A new species of Scirpus ser. Actaeogeton is described from Japan. The species， Scirpus orthorhizomatus，di ffers from S. hondoensis by the erect rhizome. Series Actaeogeton of Scirpus is represented orthorhizomatus，is related to S. hondoensis by seven species in Jap an and its neighbouring Ohwir anging in northern Honshu (Fig. 3A)，in regions (Koyama 1958). Wec ollected un- having tufted culms，th in membranous scales， known species in northern Honshu and hypogenous bristles and 3s tigmas，bu t differs Hokkaido in 1992. This，n amed Scirpus by erect rhizomes and the bracts usually ob- Fig. L Habit of Scirpus orthorhizomatus Arai & Miyam.，K arabuki-shitsugen，T azawako- cho，Senboku古un，Akita Pref.，al t. 900 m，1 1 Sept. 1992. 一-297一一 298 植物研究雑誌第72巻第5号平成9年10月 6~h Fig.2. Scirpus orthorhizomatus Arai & Miyam. (holotype): 1-6. 1: habit，2 : inflorescence，3: scale，4: stigma，5: achene and hypogynous bristles，6: horizontal section of achene. S. hondoensis Ohwi. 7: rhizome. Bar indicates 2c m (1 and 7)， 8m m( 2) or 1m m( 3-6). October 1997 Journal of Japanese Botany YOl. 72 No. 5 299 liquely bent. ap seudolateral head with (3-)5-13 spike1ets. Bract 1，cu lm-like，4 .4-10.7 cml ong，us ual1y Scirpus orthorhizomatus Arai & Miyam.， ob1iquely bent，sh allowly 1-furrowed in front， sp. nov. (Figs. 1-2) tapering to as hort pointed apex. Spike1ets Species ab Scirpo hondoensi Ohwi ovate to elliptic，7 .2-11.7m m1 ong，3 .7-6.8 rhizomatibus erectis et bracteis obliquis vel mmw ide，ac ute to obtuse at apex，r ounded at horizontalibus nec erectis bene differt. basesessile，yellowish green and yellowish ラ Rhizome thickish，li gneous，er ect，no t creep- brown later. ScaIes ob1ong to obovate，2. 9-3.9 ing，fr equently branching. Culms tufted，er ect， mml ong，1 .6-2.3 mmw ide，y ellowish green terete，5 1.5-74.6 cm tall，1. 2-2.2 mmt hick， and yellowish brown later，b rown striate on yellowish green，ob scurely striate，su rrounded both sides，f aintly many nerved especially at base with 2-3 sheaths. Basal sheaths tight， lower half，m idrib yel10wish green，a pex membranous; thelowestonescaly，1. 2-5.1 cm abruptly rounded with as hort green mucro. long，o blique-truncate at apex，d ark brown， Stamens 3; anthers oblong，0. 7-0.9 mmlo ng. slightly shining when dry; the uppermost one Achenes obovate，1. 5-1.9m ml ong，1. 1-1.5 8.6-15.6 cm long，m outh oblique and with mmw ide，0 .5-0.8 mmt hick，c ompressed setaceous elongation 6.5-16 mml ong，y el- trigonous orunequally biconvex，ap ex abruptly lowish green or light brown. Inflorescence of contracted，b asally cuneate，b rownish black Fig. 3. Distribution ofthe two species of Scirpus，S. hondoensis (A) andS. orthorhizomαtus (B) in Jap an. 300 植物研究雑誌第72巻第5号平成9年10月 when mature，g lossy，t ransversely wrinkled; K. Arai 922057-922065，8 S ept. 1992 (TI， style 1-1.8 mml ong，s tigmata 3( rarely 2)， TUAT); Sapporo，Fa urie 3044，30 Aug. 1888 filiform; hypogynous bristles 6( rarely 5)，sl en- (P). der，w hitish yellow，w ith retrorsely scabrous Distr. Japan，N orthern Honshu and spinules，2. 1-2.9 mml ong，sh orter to slightly Hokkaido，en demic (Fig. 3B). longer than achene. Japanese name: Michinoku-hotarui，no v. Wew ish to express our sincere thanks to TYPE: Japan， Karabuki-shitsugen， Professor Hideaki Ohba，t he University of Tazawako-cho，S enboku-gun，A kita Pref.，K . Tokyo，fo r his advices. Our gratitudes are also Arai 922094，1 1 Sept. 1992 (TI-holo，E ，G H， due to the curators of the following herbaria: MO，P ，T NS，T UAT-iso). MAK，P，T I. Other examined specimens. Japan，Ak ita: Nanamagari pass，U go-cho，O gachi-gun，K . Endnote Arai 922098-922101，1 2 Sept. 1992 (TI， l)Present address: Karuizawa Botanical TUAT). Aomori: Kakure-numa，Ni shitsugaru- Garden，H occhi 1166，K aruizawa-machi， gun，T sugaru Penin.，H . Hara et al. 1322370， Kitasaku-gun，N agano，3 89心1JAPAN. 15 Sept. 1974 (TI); Mt. Osoreyama，O hhata，現住所:軽井沢町植物園. 1) Shimokita-gun，F. Miyamoto 77233，13 Sept. 1979 (TUAT); ibid.，O. Mori 18579，20 Aug. References KoyamaT . 1958. Taxonomic Study ofthe Genus Scirpus Linne. 1959 (MAK). Hokkaido: Uryu-cho，Ur yu-gun， Journ. Fac. Sci. Univ. Tokyo，IU ，7( 6): 284，298-299. 新井勝利，宮本太:日本産ホタルイ属の1新 l} 種本件|北部，北海道からホタルイ属の l新種果期にその直葉が反る点で異なる. ミチノクホタ (Scirpus orthorhizomatus) を記載した.この種は，ルイの和名を提唱する. ミヤマホタルイ (S.hondoensis Ohwi)に類似して (東京農業大学農学部農学科) いるが，根茎が地中から直立していること，普通