Leersia hexandra Sw., Poaceae

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Present on Pacific Islands?  yes

Primarily a threat at high elevations?  no

Other Latin names:  Homalocenchrus hexandrus (Sw.) Kuntze

Common name(s): [more details]

Chinese: li shi he

English: clubhead cutgrass, cutgrass, southern cutgrass, swamp rice grass

Filipino: barit

Spanish: arrocillo, arroz bravo, hierba de arroz, pasto de agua

Habit:  grass

Description:  "A perennial grass; culms hollow, usually creeping and rooting at the base, the upper part erect, slender, with fine longitudinal lines, 30 to 120 cm tall; leaf sheath with thickened, fleshy, cuff-like base (sheath-node) which is densely covered with white-rough hairs bent or turned over backward; ligule 4 to 9 mm, smooth, sometimes thin and rather stiff and dry (scarious); blades tapering at base, acute, rough on both sides, rolled at night or when dry, 15 to 30 cm long, 4 to 6 mm wide; panicles erect or nodding, 5 to 12 cm, spreading or contracted, the branches slender, naked at base; spikelets in two series, overlapping, with a small knoblike projection (callus) at the base of the spikelet, 2.5 to 4.5 mm; outer bracts white or purple between green nerves, five-nerved, the mid-nerves comb-like, the inner bract much narrower, acute, three-nerved; fruit (caryopsis) oblong, but seldom produced.  The hollow slender culms with fine longitudinal lines and the outer bracts of the spikelets with comb-like (pectinate) projections extending from the mid-nerves are distinguishing characteristics of this species"  (Holm et al., 1977; p. 303).

"Perennial; culms 30 cm to 1 m high, slender, often decumbent, ascending from a creeping rhizome, silky pubescent at the nodes.  Leaf-blades mostly 10-20 cm long and 4-8 mm broad, flat, painfully retrorsely scabrid on the midrib beneath; ligule 1-2 mm long, asymmetric, truncate or obliquely truncate.  Panicle narrowly elliptic to oblong, 5-12 cm long and 1-4 cm wide; branches ascending, bearing spikelets almost to the base. Spikelets oblong, (3.2-) 3.4-4.8 (-5.2) mm long and (1-) 1.2-1.4 (-1.7) mm broad, pale or purplish; lemma conspicuously pectinate-ciliate, or rarely spinulose, on the keel" (Clayton, 1970; pp. 25, 27).

Description from GrassBase.

Habitat/ecology:  "It is a salt-shy grass found on permanent moist or marshy habitats, along irrigation ditches and other watersides, in humid thickets, in ponds, in rice fields, and on moist arable lands.  The species can extend into temperate climates whether by reason of latitude or the presence of high valleys or tablelands in the tropics, and it ha, therefore, a most interesting distribution and adaptation"  (Holm et al., 1977; p. 303).

In east Africa, "in shallow water, often forming extensive matted carpets on flood plains and in swamps, up to 2000 m" (Clayton, 1970; pp. 25, 27).

Propagation:  "The plant reproduces by seeds but is easily propagated by division of rhizomes.  The culms are often creeping and, if they are cut into pieces and spread on wet soil, they root at every node" (Holm et al., 1977; p. 303).

Native range:  Tropical America (Holm et al., 1977; p. 303).

Presence:

Pacific
Country/Terr./St. & Island group	Location	Cited status & Cited as invasive & Cited as cultivated & Cited as aboriginal introduction?	Reference & Comments
Ecuador (Galápagos Islands) Santa Cruz Group	Santa Cruz Island	introduced invasive	Charles Darwin Foundation (2008)
Papua New Guinea Papua New Guinea (eastern New Guinea Island)	Papua New Guinea (eastern New Guinea Island)		Henty, E. E. (1969) (p. 117) In wet situations from near sea level to 7000 ft., usually gregarious, on marshy land, or in the shallow water of lake-edges. It is often a major constituent of the floating islands which are a feature of several New Guinea lakes and rivers.
Philippines Philippine Islands	Philippine Islands	introduced invasive	Waterhouse, D. F. (1993) (pp. 66, 77)
Philippines Philippine Islands	Philippine Islands	cultivated	Merrill, Elmer D. (1925) (p. 78) In open wet places at low and medium altitudes, ascending to 1,500 m. Cultivated in paddies for green forage.

Pacific Rim
Country/Terr./St. & Island group	Location	Cited status & Cited as invasive & Cited as cultivated & Cited as aboriginal introduction?	Reference & Comments
Australia Australia (continental)	Queensland	introduced invasive	Holm, Leroy G./Plucknett, D. L./Pancho, J. V./Herberger, J. P. (1977) (p. 305)
Cambodia Cambodia	Cambodia (Kingdom of)	introduced invasive	Waterhouse, D. F. (1993) (pp. 66, 77)
China China	China (People's Republic of)		Hafliger, Ernst/Scholz, Hildemar (1980) (p. 92)
China China	Hong Kong	native	Wu, Te-lin (2001) (p. 339) Along streams, in marshes.
Indonesia Indonesia	Indonesia (Republic of)	introduced invasive	Waterhouse, D. F. (1993) (pp. 66, 77)
Malaysia Malaysia	Malaysia (country of)	introduced invasive	Waterhouse, D. F. (1993) (pp. 66, 77)
Mexico Mexico	Mexico (United Mexican States)		Hafliger, Ernst/Scholz, Hildemar (1980) (p. 92)
Negara Brunei Darussalam Brunei	Brunei (Negara Brunei Darussalam)	introduced invasive	Waterhouse, D. F. (1993) (pp. 66, 77)
Singapore Singapore	Singapore (Republic of)	introduced invasive	Waterhouse, D. F. (1993) (pp. 66, 77)
Singapore Singapore	Singapore (Republic of)	uncertain if introduced invasive	Chong, Kwek Yan/Tan, Hugh T. W./Corlett, Richard T. (2009) (p. 53) Weed of uncertain origin
Thailand Thailand	Thailand (Kingdom of)	introduced invasive	Waterhouse, D. F. (1993) (pp. 66, 77)
Vietnam Vietnam	Vietnam (Socialist Republic of)	introduced invasive	Waterhouse, D. F. (1993) (pp. 66, 77)

Comments:  A valuable fodder grass, but also a weed of numerous crops (Holm et al., 1977; p. 609).

Additional information:
Additional online information about Leersia hexandra is available from the Hawaiian Ecosystems at Risk project (HEAR).

Information about Leersia hexandra as a weed (worldwide references) may be available from the Global Compendium of Weeds (GCW).

Taxonomic information about Leersia hexandra may be available from the Germplasm Resources Information Network (GRIN).

References:

Charles Darwin Foundation. 2008. Database inventory of introduced plant species in the rural and urban zones of Galapagos. Charles Darwin Foundation, Galapagos, Ecuador.

Charles Darwin Research Station. 2005. CDRS Herbarium records.

Chong, Kwek Yan/Tan, Hugh T. W./Corlett, Richard T. 2009. A checklist of the total vascular plant flora of Singapore: native, naturalised and cultivated species. Raffles Museum of Biodiversity Research, National University of Singapore. 273 pp.

Clayton, W. D. 1970. Gramineae (Part 1). In: Flora of tropical East Africa, E. Milne-Redhead and R. M. Polhill, eds. Crown Agents, London.

Hafliger, Ernst/Scholz, Hildemar. 1980. Grass weeds, vol. 2. CIBA-GEIGY Ltd., Basle, Switzerland. 137 pp. + plates.

Henty, E. E. 1969. A manual of the grasses of New Guinea. Department of Forests, Division of Botany, Botany Bull. No. 1. Lae, New Guinea. 215 pp.

Holm, Leroy G./Plucknett, D. L./Pancho, J. V./Herberger, J. P. 1977. The world’s worst weeds: distribution and biology. East-West Center/University Press of Hawaii. 609 pp.

Merrill, Elmer D. 1925. An enumeration of Philippine flowering plants, vol. 1 [reprint]. Bureau of Printing, Manila. 463 pp.

U.S. Dept. Agr., Agr. Res. Serv. 2011. National Genetic Resources Program. Germplasm Resources Information Network (GRIN). Online searchable database.

Waterhouse, D. F. 1993. The major arthropod pests and weeds of agriculture in Southeast Asia. The Australian Centre for International Agricultural Research, Canberra. 141 pp.

Wu, Te-lin. 2001. Check List of Hong Kong Plants. Hong Kong Herbarium and the South China Institute of Botany. Agriculture, Fisheries and Conservation Department Bulletin 1 (revised). 384 pp.

Zhengyi, Wu/Raven, Peter H./Deyuan, Hong. 2011. Flora of China (online resource).