Glyceria fluitans
Glyceria septentrionalis
floating mannagrass, floating sweet-grass, glycerie flottante, water manna grass
eastern manna grass, floating manna grass, glycerie septentrionale, northern glyceria, northern mannagrass
20-150 cm tall, 2-4 mm thick, erect or spreading, sometimes decumbent and rooting from the lower nodes, distal portion sometimes floating in shallow water.
73-182 cm tall, to 8 mm thick, often decumbent and rooting from the lower nodes.
glabrous, keeled;
ligules 5-15 mm;
blades 5-25 cm long, 3-10 mm wide, both surfaces smooth.
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.
10-50 cm long, 2-3 cm wide;
branches 3-5 cm, paired or solitary, usually appressed to ascending, divergent at anthesis, with 1-4 spikelets;
pedicels 0.8-20 mm.
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.
(15)18-39 mm long, 1.7-3.3 mm wide, cylindrical and terete, except slightly laterally compressed at anthesis, rectangular in side view, with 8-16 florets.
(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.
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.
1.3-3.9 mm;
upper glumes 2.7-5 mm;
rachilla internodes 1.9-2.5 mm;
lemmas 5.2-8 mm, midveins extending to within 0.1 mm of the apical margins, scabrous over and between the veins, prickles about 0.05 mm, apices acute, usually entire;
paleas from shorter than to 0.6(1.5) mm longer than the lemmas, keels winged, apices bifid, teeth 0.1-0.4 mm, parallel to convergent, sometimes crossing when dry;
anthers 1.5-3 mm, usually purple.
2-3 mm.
1.5-2 mm;
hila about as long as the caryopses.
= 40.
Glyceria fluitans
Glyceria septentrionalis
Glyceria fluitans is a Eurasian species. In the Americas, it has been collected from British Columbia to California on the west coast, in South Dakota, and from Newfoundland to Pennsylvania on the eastern seaboard. In Europe, it grows in rich, organic, wet soils, often near G. notata, with which it hybridizes. It is less tolerant of trampling than G. notata. Many earlier reports from eastern Canada are based on G. borealis or G. septentrionalis (Dore and McNeill 1980; Scoggan 1978). In western North America, it has been confused with G. xoccidentalis. It tends to differ from all three in its longer lemmas and anthers. Nevertheless, identification of some specimens will prove troublesome. For further discussion, see under the species mentioned.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
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.)
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 |
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