This section is from the book "A Manual Of Weeds", by Ada E. Georgia. Also available from Amazon: A Manual Of Weeds.
Native. Perennial. Propagates by seeds and by rootstocks.
Time of bloom: August to September.
Seed-time: September to October.
Range: Newfoundland to western Ontario, southward to Florida and Texas. Habitat: Swamps, and along streams and ditches.
A bothersome weed in open ditches, which are frequently clogged by the dense, tangled masses of its interlacing rootstocks. Culms two to, four feet long, rather stout, decumbent at base, much branched. Sheaths shorter than the internodes, very rough; blades three to ten inches long, one-fourth to nearly one-half inch wide, very rough, the edges capable of cutting like a knife when drawn through the fingers. Panicle loosely branched, lax and bending, five to eight inches long, the one-seeded spikelets arranged in single rows on the branchlets and overlapping one another; they have no glumes and the lemma is boat-shaped, sharply keeled, awnless, hard, and bristly, folded over the palea, by strong marginal nerves. (Fig. 12.)
Ditches infested with this weed have to be dug out, and the task should be done before any seed has matured to float downstream in the hairy, boat-like husks.
Fig. 12. - Rice Cut-grass (Leersia ory-zoides). X 1/5.
Fig. 13. - Canary-grass (Pha-laris canariensis). X 1/4.