Annuals, Terrestrial, not aquatic, Stems nodes swollen or brittle, Stems erect or ascending, Stems caespitose, tufted, or clustered, Stems terete, round in cross section, or polygonal, Stem internodes hollow, Stems with inflorescence less than 1 m tall, Stems, culms, or scapes exceeding basal leaves, Leaves mostly cauline, Leaves conspicuously 2-ranked, distichous, Leaves sheathing at base, Leaf sheath mostly closed, Leaf sheath mostly open, or loose, Leaf sheath smooth, glabrous, Leaf sheath or blade keeled, Leaf sheath and blade differentiated, Leaf blades linear, Leaf blades very narrow or filiform, less than 2 mm wide, Leaf blades 2-10 mm wide, Leaf blades mostly flat, Leaf blade margins folded, involute, or conduplicate, Leaf blades mostly glabrous, Ligule present, Ligule an unfringed eciliate membrane, Inflorescence terminal, Inflorescence a contracted panicle, narrowly paniculate, branches appressed or ascending, Inflorescence a dense slender spike-like panicle or raceme, branches contracted, Inflorescence solitary, with 1 spike, fascicle, glomerule, head, or cluster per stem or culm, Inflorescence with 2-10 branches, Inflorescence branches more than 10 to numerous, Flowers bisexual, Spikelets pedicellate, Spikelets laterally compressed, Spikelet less than 3 mm wide, Spikelets with 3-7 florets, Spikelets solitary at rachis nodes, Spikelets all alike and fertille, Spikelets bisexual, Spikelets disarticulating above the glumes, glumes persistent, Spikelets disarticulating beneath or between the florets, Rachilla or pedicel glabrous, Glumes present, empty bracts, Glumes 2 clearly present, Glumes equal or subequal, Glumes shorter than adjacent lemma, Glumes keeled or winged, Glumes 1 nerved, Glumes 3 nerved, Lemmas thin, chartaceous, hyaline, cartilaginous, or membranous, Lemma similar in texture to glumes, Lem ma 5-7 nerved, Lemma glabrous, Lemma body or surface hairy, Lemma apex truncate, rounded, or obtuse, Lemma apex acute or acuminate, Lemma awnless, Lemma margins thin, lying flat, Lemma straight, Callus or base of lemma evidently hairy, Callus hairs shorter than lemma, Palea present, well developed, Palea about equal to lemma, Palea 2 nerved or 2 keeled, Palea keels winged, scabrous, or ciliate, Stamens 3, Styles 2-fid, deeply 2-branched, Stigmas 2, Fruit - caryopsis, Caryopsis ellipsoid, longitudinally grooved, hilum long-linear.
FNA 2007, Gould 1988
Common Name: Bigelow's bluegrass Duration: Annual Nativity: Native Lifeform: Graminoid General: Tufted annual grass, stems 15-45 cm tall, delicate and erect. Vegetative: Sheaths open, slightly keeled at bottom, broad; blades flat, soft, light green, 2-4 mm wide, 4-12 cm long, the tips boat shaped, median lines present; ligule membranous, acute, lacerate, 1-3 mm long. Inflorescence: Contracted panicle, the branches strictly erect, 5-15 cm long; spikelets broadly ovate, pale green, 4.5-8 mm, with 3-8 florets overlapping and compressed against each other, spreading apart at maturity; glumes glabrous; first glume one to three nerved, second glume three-nerved; lemmas 3-4 mm long, margins white hairy and membranous, base with dense cottony tuft or web. Ecology: Found on rocky slopes and sandy desert washes from 1,000-5,000 (305-1524 m); flowers in the spring. Distribution: s CA, s NV, s UT, AZ, s CO, NM, s TX, OK; south to c MEX. Notes: Distinguished by being an annual bunchgrass with a contracted panicle, and spikelets with multiple florets with conspicuously webbed lemmas, each floret pubescent at base. Poa annua is another annual Poa, but it is much smaller (5-20 cm tall), has open panicles with spreading branches, and usually has a prostrate growth form. Ethnobotany: Unknown Etymology: Poa is Greek for name for grass or pasturage; bigelovii is named for Dr. John Milton Bigelow (1804-1878) a botanist on the Whipple expedition. Synonyms: None Editor: SBuckley 2010, FSCoburn 2015