Glyceria obtusa
Glyceria maxima
Atlantic manna grass
English watergrass, giant mannagrass, glycerie aquatique, reed manna grass, rough mannagrass, tall glyceria, tall mannagrass
60-100 cm tall, 2.5-5 mm thick, often decumbent at the base.
60-250 cm tall, 6-12 mm thick, erect.
glabrous, smooth, not keeled, midvein prominent;
ligules 0.5-0.8 mm, not translucent, truncate to slightly rounded;
blades 15-40 cm long, 2-8 mm wide, abaxial surfaces smooth, adaxial surfaces scabridulous.
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.
5-15 cm long, 2.5-6 cm wide, ovoid, erect, dense;
branches 2.5- 8 cm, strongly ascending, with 10-30 spikelets;
pedicels 1-14 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.
4-7 mm long, 2.5-4 mm wide, somewhat laterally compressed, oval in side view, with 4-7 florets.
5-12 mm long, 2-3.5 mm wide, somewhat laterally compressed, oval in side view, with 4-10 florets.
keeled, 1-veined, veins not extending to the apical margins, apical margins hyaline, acute, entire or often splitting with age;
lower glumes 1.6-2.5 mm, lanceolate to narrowly ovate or obovate;
upper glumes 1.7-3.5 mm, ovate-elliptic to obovate, obtuse to rounded;
rachilla internodes 0.2-0.4 mm;
lemmas 3-3.9 mm, 5-9-veined, veins not raised, apices rounded, somewhat prow-shaped;
paleas subequal to the lemmas, lengths 2-2.8 times widths, keels well-developed, not winged, tips pointing towards each other, narrowly notched between the keels;
anthers 2, 0.6-0.8 mm.
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.
1.5-1.8 mm.
1.5-2 mm.
= 40.
= 60.
Glyceria obtusa
Glyceria maxima
Glyceria obtusa is a distinctive species that grows in wet woods, swamps, and shallow waters, primarily on the eastern seaboard of North America, from Nova Scotia and New Brunswick to South Carolina.
(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.)
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