Glyceria ×occidentalis
Glyceria leptostachya
northwestern manna grass, western manna grass
Davy mannagrass, manna grass, narrow manna grass, slender-spike manna grass
60-160 cm tall, 2.5-5 mm thick, erect or decumbent and rooting from the lower nodes.
50-100 (150) cm tall, 3-8 mm thick, spongy, erect to decumbent and rooting at the lower nodes.
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.
finely scabridulous, not or weakly keeled;
ligules 4.5-12 mm, lacerate;
blades 12-30 cm long, 3.5-11 mm wide, both surfaces sometimes scabridulous, adaxial surfaces sometimes sparsely papillose.
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.
20-40 cm long, 2.5-8 cm wide;
branches 4.2-14.7 cm, appressed to ascending, with 3-8(10) spikelets;
pedicels 2-5 mm, scabrous.
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.
9-20 mm long, 0.4-3 mm wide, cylindrical and terete, except at anthesis when slightly laterally compressed, rectangular in side view, with 6-15 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.
broadly rounded to acute;
lower glumes 0.6-2.1 mm;
upper glumes 1.4-3.4 mm;
rachilla internodes 1-1.5 mm;
lemmas 2.6-4.5 mm, somewhat indented below the apical margins at maturity, veins raised, scabridulous to scabrous over and between the veins, prickles about 0.05 mm, midveins extending to within 0.1 mm of the apical margins, apices truncate to obtuse, crenulate;
paleas shorter than or equaling the lemmas, keels winged, tips parallel, intercostal region truncate or rounded, sometimes exceeding the keel tips;
anthers 3, 0.3-0.9 mm.
= 40.
= 40.
Glyceria ×occidentalis
Glyceria leptostachya
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.)
Glyceria leptostachya grows in swamps and along the margins of streams and lakes, on the western side of the coastal mountains from southern Alaska to San Francisco Bay. It is similar to the European Glyceria notata, differing primarily in its tendency to have fewer spikelets [3-8(10) vs. 5-15(19)] on its branches.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
- Local floras:
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WildflowerSearch
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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
