Microstegium vimineum (Trin.) A.Camus

Chen, H., Veldkamp, J. - F. & Kuoh, C. - S., 2012, Taxonomic revision of Microstegium s. str. Andropogoneae, Poaceae), Blumea 57 (2), pp. 160-189 : 182-184

16. Microstegium vimineum (Trin.) A.Camus — Map 12

Microstegium vimineum (Trin.) A. Camus (1921) 201. — Andropogon vimineus Trin. (1832) 268. — Eulalia viminea (Trin.) Kuntze (1891) 775. — Pollinia viminea (Trin.) Merr.(1923) 35. — [ Microstegium vimineum (Trin.) A.Camus var. typicum Honda (1930) 407, nom. inval.]. — [ Pogonatherum glabratum (Brongn.) Roberty subvar. vimineum (Trin.) Roberty (1960) 389, nom. inval.]. — Type: Wallich Cat. 8838 in Herb. Trinius 329.1 (holo LE, fragm., microfiche IDC BT-16/1; CAL, E, G, K, NY, microfiche IDC 7394; L, P, MO) Bor (1952) and Sur (1985) cite ‘ 8832 ’ (CAL), which is the type of Pollinia imberbis . We suggest this is a misprint.

Microstegium willdenovianum Nees (1836) 447, nom. superfl. — Pollinia willdenoviana (Nees) Benth. (1881) 67 (‘ willdenowianum ’), nom. superfl. — Pollinia imberbis Nees ex Steud. var. willdenoviana (Nees) Hack. (1889) 178, nom. superfl. — Microstegium vimineum (Trin.) A.Camus var. willdenovianum Hack. ex A. Camus (1922) 260 (‘ willdenowiana Hack.’), nom. inval. (autonym required); Sur (1985) 175, isonym. — [ Microstegium vimineum (Trin.) A.Camus forma willdenovianum Osada (1993) 702, t., nom. inval.]. — Type: ‘ Nepal Herb. Willd. ’ (holo B, but not found in IDC microfiche 7440 sub Andropogon or Arthraxon while there is no Microstegium or Pollinia at all).

Pollinia imberbis Nees ex Steud. (1854b) 410. — [ Pollinia imberbis Nees ex Steud.var. genuina Hack.(1889) 178, nom.inval.]. — Eulalia viminea (Trin.) Kuntze var. imberbis (Nees ex Steud.) Kuntze (1891) 775. — Microstegium vimineum (Trin.)A.Camus var. imberbe (Nees ex Steud.) Honda (1930) 408. — [ Pogonatherum glabratum (Brongn.) Roberty subvar. imberbe (Nees ex Steud.) Roberty (1960) 388, nom. inval.]. — Microstegium imberbe (Nees ex Steud.) Tzvelev (1961) 22. — Type: Wallich Cat. 8832 (holo B, lost?; BM, CAL, E, G, K, microfiche IDC 7394; P).

Pollinia japonica Miq. var. monostachya Franch. & Sav. (1877) 190; (1878) 608. — Pollinia imberbis Nees ex Steud. forma monostachya (Franch. & Sav.) Hack. [(1889) 178, nom. in dub.]; ex Nakai (1914) # 172c; ex T. Mori (1922) 52, isonym. — Microstegium vimineum (Trin.) A.Camus var. monostachyum (Franch.& Sav.) Nakai (1952) 139. — [ Pogonatherum glabratum (Brongn.) Roberty subvar. monostachyum (Franch. & Sav.) Roberty (1960) 389, nom. inval. (‘ monostachys ’)]. — Type: Savatier 2565 p.p. (holo P).

[ Pollinia japonica Miq. var. polystachya Franch. & Sav. (1877) 190; (1878) 608, pro specim. — Microstegium vimineum (Trin.) A.Camus var. polystachyum (Franch. & Sav.) Ohwi (1942a) 156,pro specim. — Microstegium vimineum (Trin.) A.Camus forma polystachyum (Franch.& Sav.) T. Koyama (1971) 65, pro specim. — Voucher: Savatier 2565 p.p. (P)].

Pollinia debilis Balansa (1890) 82. — Microstegium debile (Balansa) A. Camus (1921) 201. — [ Pogonatherum glabratum (Brongn.) Roberty subvar. debile (Balansa) Roberty (1960) 388,nom.inval.]. — Type: Balansa 1741 (holo L; G, K, P).

Eulalia viminea (Trin.) Kuntze var. variabilis Kuntze (1891) 775. — Type: Kuntze s.n. (holo NY, n.v.).

Arthraxon nodosus Kom.(1901) 448;Welzen (1981) 295. — Microstegium nodosum (Kom.) Tzvelev(1961) 23. — Microstegium vimineum (Trin.)A.Camus subsp. nodosum (Kom.) Tzvelev (1976) 695. — Lectotype: Komarov 28 Aug. 1897? = 126 (holo LE; P, TI), designated by Tzvelev (1976: 695).

Pollinia cantonensis Rendle (1904) 354. — Microstegium cantonense (Rendle) A. Camus (1921) 20. — Eulalia cantonensis (Rendle) Hitchc. (1931, ‘1929’) 234. — Type: Sampson in Herb. Hance 14923 p.p. (holo BM; K).

Pollinia imberbis Nees ex Steud. subvar. latifolia Matsuda (1911) (281). — Type: probably Matsuda Ao 1892 (holo TI).

Pollinia imberbis Nees ex Steud. forma glabriflora Hack. ex Nakai (1914) 15. — Syntypes: Taquet 1833, 1835, 1912, 5052, 6109, 6110, Nakai Ao 1913, Nakai 4886.

Pollinia imberbis Nees ex Steud. var. geniculata Hack. ex Makino & Nemoto (1925) 1490. — Type: Book not seen. Not in Chase & Niles (1962).

Microstegium dilatatum Koidz. (1930) 38. — Lectotype: Faurie 6410 (holo KYO; P), designated here.

Microstegium aristulatum Robyns & Tournay (1955) 240. — Type: Scaetta 1613 (holo BR; K, P).

Microstegium reticulatum B.S.Sun ex H.Peng & X.Yang (1996) 213, t. 1, f. 1–10. — Type: H. Peng 1448 (holo YUKU).

Andropogon lasiocoleos auct. non Steud.: Steud. (1854b) 383, quoad Buerger s.n. — Arthraxon lanceolatus Miq. (1866) 288 ( ‘ lanceolatum ’), non Hochst. (1856). — Lectotype: Buerger s.n. (holo L, sh. 908.83-1054), designated here.

Annuals, mat-forming. Culms decumbent, of moderate stature, 10–50 cm long, rooting from the lower nodes. Nodes glabrous or pubescent. Sheaths glabrous, outer margin glabrous or hairy, oral hairs absent, or scanty, ciliate. Ligule a glabrous membrane, 0.5–1.5 mm long. Blades elliptic or oblong, 5–10 cm by 7–15(–19) mm, firm, base attenuate to slightly rounded, pseudopetiole absent, margins scabrous, apex acute or acuminate, glabrous to densely pilose on both sides, with or without tubercle-based hairs. Panicles 3–9 cm long, common axis 0–2.5 cm long. Racemes 1–6, solitary or digitate, erect or patent, straight, 3–7 cm long. Rachis fragile, flattened, margins ciliate, internodes linear, 4–5 mm long. Sessile spikelets without a short stalk, deciduous with the adjacent joint and pedicel, elliptic to lanceolate, 3.5–6.5 mm long, callus glabrous or pilose. Lower glume elliptic to lanceolate, coriaceous, midrib glabrous, dorsally longitudinally grooved, smooth, glabrous, margins glabrous or ciliate, apex obtuse or acute, entire or erose. Upper glume elliptic, back acute, glabrous, midrib glabrous, apex entire, acute, muticous. Lower florets absent to present and well-developed, paleate, male. Lower lemma present or absent, oblong, 1.5–3.5 mm long, muticous. Upper lemma linear, 0.5–2 mm long, veined, glabrous, apex incised to 0.25th of the lemma length, apex mucronate or awned, awn apical or from a sinus, awn straight or geniculate, column absent or straight to slightly twisted, 1–32 mm long. Upper palea absent to present, oblong, 0.5–2 mm long, as long as the lemma, membranous, apex entire. Anthers 3, 0.3–0.5 mm long. Pedicels linear, flattened, 3.5–4.5 mm long, margins pubescent. Pedicelled spikelets subequal to the sessile ones.

Distribution — Africa ( Congo, Cameroon), NW Iran, Paki- stan, India (W Bengal, Himachal Pradesh, Meghalaya, Nagaland), Sikkim, Bhutan, Nepal, Burma (Chin), Indo-China to the Ryukyu Islands, Japan (Hokkaido, Honshu, Kyushu, Shikoku), Korea, introduced in the Caucasus, Iran, Turkey, United States (East and Gulf Coast); Malesia, apparently very rare and local, extant?: Java (Backer 16258 (BO): Pekalongan, Yosorejo, LÖrzing 162, 163, 289 (BO): Sindoro near Sibajak, not in Monod de Froideville (1968), Philippines (Luzon, Mt Polis, Mt Pulog).

Habitat — Very wide, from saturated wetlands to rocky areas, under closed canopies, along paths, ditches, disturbed areas, 1200–2000 m altitude.

Vernacular name — Japanese stilt grass, Nepalese brown- top.

Uses — Regarded as a noxious weed in the USA ( Ehrenfeld 1999, who described it as a rhizomatous perennial).

Notes — According to many authors there would be two infra-specific taxa based on the presence or absence of an awn in the sessile spikelets ( ‘ imberbe , willdenovianum ’). The form without an awn is perhaps at most to be called Microstegium vimineum forma willdenovianum . Inflorescences with muticous basal spikelets were described as Eulalia viminea var. variabilis . Sometimes the pedicelled spikelet is so much reduced, that in keys the genus cannot be identified ( Noltie 2000).

Camus (1922) noted cleistogamous florets here and in the synonymous M. debile , where the anthers were not exerted, but remained inside the spikelet even in fruit. Cleistogamous inflorescences would be hidden in the sheath ( Ehrenfeld 1999). Chen & Phillips (2006) noted that M. reticulatum “represents an extreme local variant from the Microstegium vimineum complex. It is distinguished from typical M. vimineum by the combination of a more delicate habit, broader leaf blades, and a conspicuously reticulately veined lower glume”. Although we have not seen the type, we find these characters insufficient to recognise the taxon at any level.

Note the disjunct distribution. Curiously, no collections from Thailand have been seen although the collections in BM, E, K, L, and P have been searched.

This species has been illustrated by Hsu (1975), Osada (1993), and Liu (1997), and by Chen & Phillips (2007) as both M. reticulatum and M. vimineum

Figures

Map 12 Distribution of Microstegium vimineum (Trin.) A.Camus.