Burke: Poa macrantha vs. Poa trivialis

	Poa macrantha	Poa trivialis
	sand-dune blue grass	rough-stalk blue grass
Habit	Strongly rhizomatous, dioecious perennial, the culms hollow, glabrous, 2-4 dm. tall.	Perennial, short-lived; loosely to densely tufted, usually weakly stoloniferous.
Leaves	Sheaths glabrous, open most of their length, but closed as least for the lower 2-3 cm.; ligules 1-1.5 mm. long, thick, strongly pubescent, truncate, highest on the sides; blades stiff and involute, in dense basal tufts, up to 3 mm. broad, 5-12 cm. long, the tips only slightly prow-like.	Basal branching intra-vaginal; culms 25-120 cm, decumbent to erect, sometimes trailing and rooting at nodes, terete or weakly compressed; nodes terete or slightly compressed, 1-3 exserted; sheaths closed for 1/3 to 1/2 of length, compressed, often densely scabrous, bases of basal sheaths glabrous, distal sheath lengths 0.5-4 times blade lengths; collars smooth or scabrous, glabrous; ligules 3-10 mm, scabrous, acute to acuminate; blades 1-5 mm wide, flat, lax, soft, sparsely scabrous over the veins, margins scabrous, apices narrowly bow-shaped.
Flowers	Inflorescence a compact panicle 4-12 cm. long, the branches short, stiff and ascending; spikelets 4- to 6-flowered, occasionally bulbiferous; glumes subequal, about 9 mm. long, 5-nerved, keeled; lemmas about 9 mm. long, 7- to 11-nerved, pubescent on the keel and marginal nerves, the rachilla also pubescent with soft, straight hairs; staminate flowers with anthers 3.5 mm. long, pistillate flowers with vestigial stamens.	Spikelets 2.3-3.5 mm, lengths 3 times widths, laterally compressed; florets 2-4, bisexual; rachilla internodes smooth or muriculate; glumes distinctly keeled, keels scabrous; lower glumes subulate to narrowly lanceolate, curved, 1-veined, distinctly shorter than the lowest lemmas; calluses webbed, hirsute, hairs over 2/3 the lemma length; lemmas 2.3-3.5 mm, lanceolate, distinctly keeled, keels usually sparsely puberulent along 3/5 of length, marginal veins usually glabrous, infrequently the proximal 1/4 softly puberulent, intercostal regions smooth, glabrous, upper lemmas sometimes glabrous, lateral veins prominent, margins glabrous, apices acute; palea keels smooth, muriculate, tuberculate, or minutely scabrous; anthers 1.3-2 mm.
Fruit		Caryopses 1-4 mm, ellipsoid, usually shallowly ventrally grooved, solid; hilum sub-basal, round or oval, to 1/6 length of the caryopses.

	Poa macrantha	Poa trivialis
Flowering time	April-July	May-July
Habitat	Sand dunes along the marine coast.	Moist deciduous forest, riparian areas, disturbed grassland, and lawns at low to middle elevations.
Distribution	Occurring west of the Cascades crest along the coast in Washington; southern Alaska to California. [WildflowerSearch map] [BONAP county map]	Occurring chiefly west of the Cascades crest in Washington; Alaska to California, east to the Atlantic Coast. [WildflowerSearch map] [BONAP county map]
Origin	Native	Introduced from Europe
Conservation status	Not of concern	Not of concern
Sibling taxa	P. alpina, P. annua, P. arctica, P. bolanderi, P. bulbosa, P. compressa, P. confinis, P. curtifolia, P. cusickii, P. fendleriana, P. glauca, P. howellii, P. infirma, P. interior, P. laxiflora, P. leibergii, P. leptocoma, P. lettermanii, P. marcida, P. ×multnomae, P. nemoralis, P. nervosa, P. palustris, P. paucispicula, P. pratensis, P. secunda, P. stenantha, P. suksdorfii, P. trivialis, P. unilateralis, P. wheeleri	P. alpina, P. annua, P. arctica, P. bolanderi, P. bulbosa, P. compressa, P. confinis, P. curtifolia, P. cusickii, P. fendleriana, P. glauca, P. howellii, P. infirma, P. interior, P. laxiflora, P. leibergii, P. leptocoma, P. lettermanii, P. macrantha, P. marcida, P. ×multnomae, P. nemoralis, P. nervosa, P. palustris, P. paucispicula, P. pratensis, P. secunda, P. stenantha, P. suksdorfii, P. unilateralis, P. wheeleri
Subordinate taxa		P. trivialis ssp. trivialis
Web links	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	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

Poa trivialis

sand-dune blue grass

rough-stalk blue grass

Habit

Strongly rhizomatous, dioecious perennial, the culms hollow, glabrous, 2-4 dm. tall.

Perennial, short-lived; loosely to densely tufted, usually weakly stoloniferous.

Leaves

Sheaths glabrous, open most of their length, but closed as least for the lower 2-3 cm.;

ligules 1-1.5 mm. long, thick, strongly pubescent, truncate, highest on the sides;

blades stiff and involute, in dense basal tufts, up to 3 mm. broad, 5-12 cm. long, the tips only slightly prow-like.

Basal branching intra-vaginal; culms 25-120 cm, decumbent to erect, sometimes trailing and rooting at nodes, terete or weakly compressed;

nodes terete or slightly compressed, 1-3 exserted;

sheaths closed for 1/3 to 1/2 of length, compressed, often densely scabrous, bases of basal sheaths glabrous, distal sheath lengths 0.5-4 times blade lengths;

collars smooth or scabrous, glabrous;

ligules 3-10 mm, scabrous, acute to acuminate;

blades 1-5 mm wide, flat, lax, soft, sparsely scabrous over the veins, margins scabrous, apices narrowly bow-shaped.

Flowers

Inflorescence a compact panicle 4-12 cm. long, the branches short, stiff and ascending;

spikelets 4- to 6-flowered, occasionally bulbiferous;

glumes subequal, about 9 mm. long, 5-nerved, keeled;

lemmas about 9 mm. long, 7- to 11-nerved, pubescent on the keel and marginal nerves, the rachilla also pubescent with soft, straight hairs; staminate flowers with anthers 3.5 mm. long, pistillate flowers with vestigial stamens.

Spikelets 2.3-3.5 mm, lengths 3 times widths, laterally compressed;

florets 2-4, bisexual;

rachilla internodes smooth or muriculate;

glumes distinctly keeled, keels scabrous;

lower glumes subulate to narrowly lanceolate, curved, 1-veined, distinctly shorter than the lowest lemmas;

calluses webbed, hirsute, hairs over 2/3 the lemma length;

lemmas 2.3-3.5 mm, lanceolate, distinctly keeled, keels usually sparsely puberulent along 3/5 of length, marginal veins usually glabrous, infrequently the proximal 1/4 softly puberulent, intercostal regions smooth, glabrous, upper lemmas sometimes glabrous, lateral veins prominent, margins glabrous, apices acute;

palea keels smooth, muriculate, tuberculate, or minutely scabrous;

anthers 1.3-2 mm.

Fruit

Caryopses 1-4 mm, ellipsoid, usually shallowly ventrally grooved, solid;

hilum sub-basal, round or oval, to 1/6 length of the caryopses.