Glyceria canadensis
Glyceria maxima
Canada mannagrass, Canadian mannagrass, rattlesnake manna grass, rattlesnake-grass
English watergrass, giant mannagrass, glycerie aquatique, reed manna grass, rough mannagrass, tall glyceria, tall mannagrass
60-150 cm tall, 2.5-5 mm thick, erect or the bases decumbent.
60-250 cm tall, 6-12 mm thick, erect.
retrorsely scabridulous to scabrous, keeled;
ligules 2-6 mm;
blades 8-36 cm long, 3-8 mm wide, abaxial surfaces smooth or scabrous, adaxial surfaces scabridulous to scabrous.
scabridulous, keeled;
ligules 1.2-6 mm, rounded or with a central point, ligules of the lower leaves thick, stiff, and opaque, ligules of the upper leaves thinner and translucent;
blades 30-60 cm long, 6-20 mm wide, both surfaces smooth or adaxial surfaces scabridulous.
10-30 cm long, 10-20 cm wide, pyramidal, open, nodding;
branches 7-20 cm, lax, divergent, often drooping, with 15-60+ spikelets;
pedicels 2.5-9 mm.
15-45 cm long, to 30 cm wide, open;
branches 8-20 cm, lax, strongly divergent or drooping at maturity, scabridulous, primary branches with 50+ spikelets;
pedicels 0.8-10 mm.
3-8 mm long, (2.5)3-5 mm wide, laterally compressed, oval in side view, with 2-10 florets.
5-12 mm long, 2-3.5 mm wide, somewhat laterally compressed, oval in side view, with 4-10 florets.
narrowing from midlength or above to the broadly (> 45°) acute or rounded apices, 1-veined, veins terminating below the apices;
lower glumes 0.6-2.4 mm, ovate to rectangular;
upper glumes 1.5-2.5 mm, lanceolate;
rachilla internodes 0.2-0.5 mm;
lemmas 1.8-4 mm, ovate in dorsal view, 5-7-veined, veins evident but not raised distally, smooth over and between the veins, apices acute, prow-shaped;
paleas 0.1-0.8 mm shorter than lemmas, lengths 1.5-1.8 times widths, almost round in dorsal view, keels well developed, not winged, tips incurved, apices narrowly notched between the keels;
anthers 2, 0.4-0.5 mm, dehiscent at maturity.
unequal, usually the midvein of 1 or both reaching to the apices;
lower glumes 2-3 mm;
upper glumes 3-4 mm, longer than wide;
rachilla internodes 0.5-1 mm;
lemmas 3-4 mm, 7-veined, veins scabridulous, apices broadly acute to rounded, slightly prow-shaped;
paleas subequal to the lemmas, lengths more than 3 times widths, keels not winged, ciliate, tips not strongly incurved, curved to broadly notched between the keels;
anthers 3, (1)1.2-2 mm.
1.5-2 mm.
1.5-2 mm.
= 60.
Glyceria canadensis
Glyceria maxima
Glyceria canadensis is an attractive native species that grows in swamps, bogs, lakeshore marshes, and wet woods throughout much of eastern North America, extending from eastern Saskatchewan to Newfoundland, Illinois, and northeastern Tennessee. It is now established in western North America, having been introduced as a weed in cranberry farms. It forms sterile hybrids with G. striata; the hybrids are called G. xottawensis Bowden. For further comments, see p. 77.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
Glyceria maxima is native to Eurasia. It grows in wet areas, including shallow water, at scattered locations in the flora region. It is an excellent fodder grass, and may have been planted deliberately at one time (Dore and McNeill 1980). At some sites, the species appears to be spreading, largely vegetatively. It is easily confused with large specimens of G. grandis, but differs in its firmer, more prow-tipped lemmas as well as its larger lemmas and usually larger anthers.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
1. Lemmas 2.4-4 mm long; spikelets 5-8 mm long, with 4-10 florets; lower glumes 1.6-2.4 mm long; upper glumes acute | var. canadensis |
1. Lemmas 1.8-2.5 mm long; spikelets 3-5 mm long, with 2-5 florets; lower glumes 0.6-1.3 mm long; upper glumes usually rounded, sometimes acute | var. laxa |
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