Glyceria declinata
Glyceria septentrionalis
low glyceria, low manna grass, waxy mannagrass
eastern manna grass, floating manna grass, glycerie septentrionale, northern glyceria, northern mannagrass
(10)20-92 cm tall, 1.5-2.5 mm thick, ascending to erect from a decumbent, branching base.
73-182 cm tall, to 8 mm thick, often decumbent and rooting from the lower nodes.
glabrous, keeled;
ligules 4-9 mm;
blades (2)3-12 cm long, 4-8 mm wide, adaxial surfaces not papillose, apices abruptly acute.
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.
6-30 cm long, 1-2.5 cm wide;
branches 1.5-9.5 cm, ascending, with 1-5 spikelets;
pedicels 1-2.5 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.
11-24 mm long, 1.3-3 mm wide, cylindrical and terete, except slightly laterally compressed at anthesis, rectangular in side view, with 8-15 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.
oval;
lower glumes 1.4-3.5 mm;
upper glumes 2.5-4.9 mm;
rachilla internodes 1.2-1.8 mm;
lemmas (3.5)4-6 mm, 7-veined, veins and intercostal regions scabridulous, prickles about 0.05 mm, midveins extending to within 0.1 mm of the apical margins, apices acute, with a well-developed lobe on one or both sides opposite the lateral veins, entire to crenulate between the lateral lobes;
paleas exceeding the lemmas by 0.2-1(1.5) mm, keels winged, apices bifid, teeth 0.3-0.5 mm;
anthers 0.5-1.4 mm, usually purple.
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.
1.8-2.5 mm.
1.5-2 mm;
hila about as long as the caryopses.
= 20.
Glyceria declinata
Glyceria septentrionalis
Glyceria declinata is a European species that is established on the western seaboard of North America from southern British Columbia to southern California, and in northeastern Nevada, Arizona, the lower portion of the Mississippi valley, and on Long Island, New York. In Europe, it grows in low-calcium, acidic soils and tolerates drier conditions than other European species of Glyceria (Conert 1992). In Denmark, it tends to grow in areas that are highly trampled (Niels Jacobsen and Signe Frederiksen, pers. comm.). It is invading vernal pools in California.
In western North America, G. declinata has been confused with G. xoccidentalis. The most reliable distinguishing characteristics are the lateral lemma lobes of G. declinata and its rather short, straight panicle branches. The two species also differ in their ploidy level, G. declinata being diploid and G. xoccidentalis tetraploid (Church 1949). This is reflected in the length of their guard cells, those of G. declinata being 0.2-0.3 um and those of G. xoccidentalis being 0.4-0.5 um.
S.F. Hrusa found plants (Hrusa 13681, 15858, 16267; specimens in CDA) that have an annual growth habit. Apart from this, they fit within the circumscription of G. declinata, except that two of the three specimens have narrower (2-3 mm) leaves than normal; they were also collected relatively early in the season. For now, it seems best to include the plants in G. declinata pending a better understanding of their relationship to perennial members of the species.
(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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