Glyceria septentrionalis
Glyceria canadensis
eastern manna grass, floating manna grass, glycerie septentrionale, northern glyceria, northern mannagrass
Canada mannagrass, Canadian mannagrass, rattlesnake manna grass, rattlesnake-grass
73-182 cm tall, to 8 mm thick, often decumbent and rooting from the lower nodes.
60-150 cm tall, 2.5-5 mm thick, erect or the bases decumbent.
smooth or scabridulous, keeled;
ligules 5-16 mm;
blades 18-32 cm long, 2-15 mm wide, abaxial surfaces scabrous, adaxial surfaces scabridulous, usually glabrous, midcauline leaves sometimes papillose.
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.
15-60 cm long, 1-3.5 cm wide;
branches 3-17 cm, usually erect to strongly ascending, sometimes spreading at anthesis, usually straight, sometimes lax, with 1-9 spikelets;
pedicels 0.7-1.7 mm.
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.
(6.5)10-23 mm long, 1-3 mm wide, cylindrical and terete, except at anthesis when slightly laterally compressed, rectangular in side view, with 8-16 florets.
3-8 mm long, (2.5)3-5 mm wide, laterally compressed, oval in side view, with 2-10 florets.
elliptic to obovate, apices rounded to acute;
lower glumes (0.3)1.5-3.7 mm;
upper glumes (1.9)2.3-5.2 mm;
rachilla internodes 1.1-1.8 mm;
lemmas 2.4-4.8 mm, veins scabrous or hispidulous, intercostal regions scabridulous, scabrous, or hispidulous, midveins extending to within 0.1 mm of the apical margins, apices truncate to obtuse or acute, apical margins crenate to entire;
paleas from slightly shorter than to exceeding the lemmas, apices bifid, teeth to 0.2 mm;
anthers 3, 0.5-1.8 mm.
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.
1.5-2 mm;
hila about as long as the caryopses.
1.5-2 mm.
Glyceria septentrionalis
Glyceria canadensis
Glyceria septentrionalis is native and restricted to North America. It grows in shallow water or very wet soils, from southern Quebec to the east coast and south to eastern Texas and South Carolina. Voss (1972) stated that it is the floating leaves of G. septentrionalis that develop papillose, non-wettable adaxial surfaces. They seem to be developed less often than in G. borealis; whether this reflects a difference in habitat or growth habit is not known.
Glyceria septentrionalis resembles G. notata in its rather short, truncate to rounded lemmas, but it tends to have fewer spikelets on its branches. In addition, the veins of its leaf sheaths appear completely smooth, even under high magnification. That said, many specimens will be hard to identify if their provenance is not known.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
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.)
1. Lemmas hispidulous over the veins, hairs about 0.1 mm long | var. arkansana |
1. Lemmas scabrous over the veins, prickles about 0.05 mm long | var. septentrionalis |
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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