Burke: Poa annua vs. Poa bulbosa

	Poa annua	Poa bulbosa
	annual blue grass	bulbous bluegrass
Habit	Glabrous annual, the culms 5-20 cm. tall, hollow, rooting at the nodes and forming mats.	Strongly tufted, glabrous perennial, the culms hollow, 1.5-4 dm. tall.
Leaves	Sheaths closed below, but open over half their length; ligules about 1 mm. long, rounded to truncate; blades 1-3.5 mm. broad, usually folded, the tip prow-like.	Sheaths open almost to the base; ligules 1.5-3 mm. long, blunt to acuminate, usually entire; blades 1-2.5 mm. broad, flat to folded, scabrous, the tip prow-like.
Flowers	Inflorescence a pyramidal panicle 3-8 cm. long, the branches spreading and somewhat rigid; spikelets 3- to 6-flowered, 4-6 mm. long; glumes unequal, the first 1-nerved, about 2 mm. long, the second 3-nerved, much the broader; florets rather distant, the rachilla visible; lemmas about 3.5 mm. long, 5-nerved, the margins purplish and papery, usually pubescent along the keel and marginal nerves; paleas slightly shorter than the lemmas, 2-keeled.	Inflorescence an open to contracted panicle up to 10 cm. long; spikelets 3-5 mm. long, but florets usually modified into elongate, purplish bulbils up to 20 mm. long; glumes 2-3 mm. long; normal lemmas about 5 per spikelet, keeled, 2-4 mm. long, webbed at base; viviparous spikelets modified into a single bulbil enclosed by the several leaf-like lemmas 5-20 mm. long; stamens and pistils mostly lacking.

	Poa annua	Poa bulbosa
Flowering time	March-August	March-June
Habitat	Lawns, fields, parking lots, sidewalks, roadsides, wastelots, prairies and grassy balds, and other disturbed, open areas.	Disturbed areas from the coast to midmontane.
Distribution	Occurring on both sides of the Cascades crest in Washington; Alaska to California, east across North America to the Atlantic Coast. [WildflowerSearch map] [BONAP county map]	Occurring on both sides of the Cascades crest in Washington; Alaska to California, east across North America to the Atlantic Coast. [WildflowerSearch map] [BONAP county map]
Origin	Introduced from Eurasia	Introduced
Conservation status	Not of concern	Not of concern
Sibling taxa	P. alpina, 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. trivialis, P. unilateralis, P. wheeleri	P. alpina, P. annua, P. arctica, P. bolanderi, 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. trivialis, P. unilateralis, P. wheeleri
Subordinate taxa		P. bulbosa ssp. vivipara
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 bulbosa

annual blue grass

bulbous bluegrass

Habit

Glabrous annual, the culms 5-20 cm. tall, hollow, rooting at the nodes and forming mats.

Strongly tufted, glabrous perennial, the culms hollow, 1.5-4 dm. tall.

Leaves

Sheaths closed below, but open over half their length;

ligules about 1 mm. long, rounded to truncate;

blades 1-3.5 mm. broad, usually folded, the tip prow-like.

Sheaths open almost to the base;

ligules 1.5-3 mm. long, blunt to acuminate, usually entire;

blades 1-2.5 mm. broad, flat to folded, scabrous, the tip prow-like.

Flowers

Inflorescence a pyramidal panicle 3-8 cm. long, the branches spreading and somewhat rigid;

spikelets 3- to 6-flowered, 4-6 mm. long;

glumes unequal, the first 1-nerved, about 2 mm. long, the second 3-nerved, much the broader;

florets rather distant, the rachilla visible;

lemmas about 3.5 mm. long, 5-nerved, the margins purplish and papery, usually pubescent along the keel and marginal nerves;

paleas slightly shorter than the lemmas, 2-keeled.

Inflorescence an open to contracted panicle up to 10 cm. long;

spikelets 3-5 mm. long, but florets usually modified into elongate, purplish bulbils up to 20 mm. long;

glumes 2-3 mm. long; normal lemmas about 5 per spikelet, keeled, 2-4 mm. long, webbed at base; viviparous spikelets modified into a single bulbil enclosed by the several leaf-like lemmas 5-20 mm. long;

stamens and pistils mostly lacking.