Poa sylvestris
Poa napensis
woodland bluegrass
Napa blue grass
30-120 cm, bases often decumbent.
30-100 cm, erect, terete, with 0(1) exserted nodes.
closed for (1/20) 1/2-7/8 their length, terete, throats frequently ciliate near the point of fusion;
ligules 0.5-2.7 mm, smooth or sparsely scabrous, truncate to obtuse;
blades 0.7-5 mm wide, flat, thin, lax.
closed for 1/10(1/8) their length, terete, bases of basal sheaths glabrous, distal sheath lengths 1.5-5 times blade lengths;
ligules 4-6 mm, scabrous, obtuse to acute;
innovation blades similar to the cauline blades;
cauline blades 1-3 mm wide, folded to involute, thick, fairly firm, pale green, abaxial surfaces scabrous, apices narrowly prow-shaped.
mainly pseudointravaginal.
intravaginal.
(6.7)9-20 cm, open, narrowly conical at maturity;
nodes with (2)3-10 branches per node;
branches (2)3-7 cm, spreading to eventually reflexed, straight, angled, angles several, densely scabrous, with 1-11 spikelets.
5-18(21) cm, erect, narrowly to broadly lanceoloid, loosely contracted, congested, with 40-100+ spikelets;
nodes with 2-3(5) branches;
branches 3-10 cm, erect to ascending, straight, angles densely scabrous, with 5-27 spikelets in the distal 1/2.
2.5-4.4 mm, laterally compressed;
florets 2-3(4);
rachilla internodes longer than (1)1.2 mm, smooth, glabrous.
(4)4.5-7 mm, lengths 3-3.5 times widths, lanceolate, laterally compressed, drab;
florets 3-5;
rachilla internodes usually shorter than 1 mm, smooth.
distinctly keeled, keels scabrous;
lower glumes 1(3)-veined;
upper glumes shorter than or subequal to the lowest lemmas;
calluses webbed;
lemmas 2.1-3.1 mm, broadly lanceolate, distinctly keeled, keels and marginal veins short-villous, extending to near the apices on the keels, lateral veins prominent, softly puberulent to short-villous, intercostal regions usually sparsely softly puberulent, smooth, apices obtuse to acute;
palea keels softly puberulent at midlength, apices finely scabrous;
anthers 1-1.8 mm.
lanceolate, slightly unequal, pale, distinctly keeled, keels sparsely scabrous;
lower glumes 3-veined;
calluses glabrous, rarely with a crown of hairs, hairs to 0.1 mm;
lemmas 3-4 mm, lanceolate, distinctly keeled, finely scabrous, usually glabrous, keels and marginal veins rarely sparsely puberulent proximally, lateral veins obscure to moderately prominent, intercostal regions muriculate, margins glabrous, apices acute;
paleas scabrous over the keels;
anthers 1.2-1.8 mm.
= 28.
= 42.
Poa sylvestris
Poa napensis
Poa sylvestris grows in southeastern Canada and throughout much of the eastern United States, mainly at low elevations in woodlands, especially in riparian zones. It is easily distinguished from P. wolfii (p. 514) by its smaller, more numerous spikelets and lemmas that are usually sparsely hairy between the veins. Plants from the middle Appalachian Mountains have been confused with P. paludigena (p. 572); P. sylvestris is usually larger, has more than 2 branches per panicle node, is pubescent between the lemma veins and palea keels, and has larger anthers.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
Poa napensis is endemic to mineralized ground around hot springs in Napa County, California. It is listed as an endangered species by the United States Fish and Wildlife Service. The sectional placement of the species is suggested by the rare occurrence of a minute crown of hairs around the callus and its possession of a chloroplast genome like that of P. secunda (p. 588).
(Discussion copyrighted by Flora of North America; reprinted with permission.)
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