Glyceria fluitans
Glyceria ×occidentalis
floating mannagrass, floating sweet-grass, glycerie flottante, water manna grass
northwestern manna grass, western manna grass
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.
60-160 cm tall, 2.5-5 mm thick, erect or 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 to scabridulous, keeled, sometimes weakly so;
ligules 7-12 mm;
blades 20-30 cm long, (2.5)4-12 mm wide, adaxial surfaces scabridulous, occasionally 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.
20-50 cm long, 2-15 cm wide, usually narrow, open at anthesis;
branches 4.5-18 cm, somewhat lax, usually ascending, strongly divergent at anthesis, with 2-8 spikelets, pedicels 1.5-8 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.
13-23 mm long, 1.5-3.5 mm wide, cylindrical and terete, except at anthesis when slightly laterally compressed, rectangular in side view, with 6-13 florets.
acute to obtuse;
lower glumes 1.1-2.8 mm;
upper glumes 2.9-3.7 mm, about twice as long as the lower glumes;
rachilla internodes 1-2.8 mm;
lemmas 4.5-5.9 mm, scabridulous, midveins extending to within 0.1 mm of the apical margins, apices acute, usually slightly lobed or irregularly crenate;
paleas usually shorter than or equaling the lemmas, sometimes slightly longer, keels winged, apices shallowly notched to slightly bifid, teeth to 0.2 mm, parallel;
anthers 2, 0.6-1.6 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.
= 40.
= 40.
Glyceria fluitans
Glyceria ×occidentalis
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 ×occidentalis has hitherto been considered an uncommon native species that grows along lakes, ponds, and streams, and in marshy areas of western North America. It differs from other species in the region primarily in its longer lemmas and anthers. Studies of chloroplast DNA in western North American species of Glyceria demonstrated that, contrary to C.L. Hitchcock's (1969) conclusion, G. fluitans is present in western North America, and that all specimens being identified as G. ×occidentalis had cpDNA resembling that of G. leptostachya or G. fluitans; there was no distinctive G. ×occidentalis cpDNA (Whipple et al. [in press]). This strongly suggests that G. ×occidentalis is a series of reciprocal hybids, and probably backcrosses, between G. fluitans and G. leptostachya. As the key indicates, G. ×occidentalis is intermediate between its two putative parents. The cpDNA study also confirmed that G. declinata is distinct from G. ×occidentalis (see discussion under that species).
(Discussion copyrighted by Flora of North America; reprinted with permission.)
- Local floras:
BC, 
CA, 
OR, 
WA - Local Web sites: CalFlora, CalPhotos,
Flora NW, 
Go Botany, 
MD Biodiversity, 
PNW Herbaria 
WildflowerSearch
iNaturalist (observations)
USDA Plants Database- LBJ Wildflower Center
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- Local floras: BC, CA, OR, WA
- Local Web sites: CalFlora, CalPhotos, Flora NW, PNW Herbaria
- WildflowerSearch
- iNaturalist (observations)
- USDA Plants Database
- LBJ Wildflower Center
- SEINet
- Plants of the World Online
- Encyclopedia of Life
- Wikipedia
- Google Image Search
