Glyceria maxima
Glyceria alnasteretum
English watergrass, giant mannagrass, glycerie aquatique, reed manna grass, rough mannagrass, tall glyceria, tall mannagrass
Aleutian glyceria
60-250 cm tall, 6-12 mm thick, erect.
60-90 cm tall, 2.5-4 mm thick, erect.
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.
smooth, not keeled;
ligules 2-3 mm, rounded to truncate;
blades 5-20 cm long, 3-7 mm wide, abaxial surfaces smooth, adaxial surfaces scabrous, apices acute.
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.
15-22 cm long, 12-16 cm wide, open, pyramidal, erect to nodding;
branches 8-10 cm, lower branches widely divergent to drooping.
5-12 mm long, 2-3.5 mm wide, somewhat laterally compressed, oval in side view, with 4-10 florets.
7-9 mm long, 3-4.5 mm wide, with 5-8 florets.
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.
unequal, lanceolate, acute;
lower glumes 2-3.5 mm;
upper glumes 2.5-3.5 mm, longer than wide;
lemmas 3-5.5 mm, 7-veined, obtuse to acute;
paleas shorter than or subequal to the lemmas, keels not winged, apices not strongly incurved, emarginate between the keels;
anthers 3, 0.7-1.2 mm.
1.5-2 mm.
not seen.
= 60.
= 20.
Glyceria maxima
Glyceria alnasteretum
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.)
Glyceria alnasteretum is included in this treatment with some hesitation, based on van Schaack 724 (W'l'LJ 152646) and van Schaack 887 (MO 1710727), both collected at Signal Point, Attu Island, Alaska in 1945. The above description is based on Komarov (1963) and Koyama (1987), modified to reflect the wider panicles and longer glumes and lemmas of the van Schaack specimens. The difference in habitat is troubling. The van Schaack specimens were found "in a beachside meadow" and "near beach." Koyama describes the habitat of G. alnasteretum as "wet meadows and marshes at high altitudes as well as subarctic zone" (p. 114). Nevertheless, the van Schaack specimens fit the description of G. alnasteretum better than any other taxon in this treatment. Clearly, further investigation is called for; it should include plants from both sides of the Bering Strait.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
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