Actinoscirpus grossus (L.f.) Goetgh. & D.A. Simpson

Actinoscirpus grossus (L.f.) Goetgh. & D.A. Simpson




Scirpus gross L.f., Hy­menochaete grossa (L.f.) Nees, Schoenoplec­tus grossus (L.f,) Palla.

Vernacular Names


Rumput menderong, rumput menerong, rumput morong.

English Giant bulrush.

Mensiang (western Sumatra), lingi (Ja­vanese), walingi (Sundanese).


Tikiu, titiu (Tagalog), agas (Bikol).

Thailand Kok, kok prue, kok saamliam (Central, Bangkok).

Chi c[os]i d[uf]i.

Geographical Distributions

Actinoscirpus gras­sus probably originated in Southeast Asia and is widely distributed in the Old World tropics from India, Sri Lanka and southern China throughout Southeast Asia to the Bonin Islands (south of Japan), Micronesia and tropical Australia.


Actinoscirpus grassus is an erect, stout, rhizomatous pe­rennial herb that can grow up to 2 m tall. The stem is sharply 3-angled with concave sides, measuring 80-200 cm x 0.5-2.5 cm, smooth, spongy, strongly septate-nodulose, with a corm-like enlargement at base, and singular growing in small groups or in dense tufts.

There are a few leaves which are sheathed and pale yel­low with spongy sheath, prominently septate-nodose and tightly surrounding the stem base. The blade is sublin­ear and measuring 50-180 cm x 1-3 cm. The lower half is keeled and 3-sided, somewhat thickish, soft and strongly sep­tate-nodulose while the upper half is almost flat and gradually acuminate, and with subscabrous margin.

The inflo­rescence is 6-15 cm long, terminal, and corymbiform with primary, sec­ondary and tertiary rays. There are 3-4 involucral bracts which are leaf-like, flat, linear, 15-70 cm long and with at least 2 overtopping the inflorescence. There are several primary rays which are spreading, unequal and scaberulous while the secondary rays are 1-4 cm long. There are numerous spikelets which are solitary, peduncled except for terminal ones, ellip­soidal, measuring 4-10 mm x 3.5-4 mm and with bisexual flowers.

The glumes are spirally arranged, appressed, con­cave-ovate, measuring about 3 mm x 2 mm, membranous, nearly smooth, prominent and with green midrib, red-brown with finely ciliolate margins and with ob­tuse to short mucronulate apex. There are 4-6 hypogynous bristles (perianth) which are retrorsely scabrous and slightly longer than the fruit. There are 3 stamens which are very short, and with linear anthers about 1 mm long. The style is 3 mm long.

The fruit is a nut­like, trigonous, obovate achene that measures about 1-2 mm x 1 mm, apiculate and brown.

Ecology / Cultivation

Actinoscirpus grossus occurs, often abundantly, in swampy or inundated locations, pools, ditches and rice fields, from sea level up to 900 m altitude. It is an important aquatic weed in Southeast Asia. In Indonesia, it is considered a weed of minor im­portance in lowland-irrigated and tidal rice fields, where it can be controlled manually, by deep-ploughing before seed formation, or with herbicides. In Peninsular Malaysia, it is one of the major weeds of transplanted rice.

Line Drawing / Photograph



  1. Plant Resources of South-East Asia No.17: Fibre plants.