Early Hair Grass

Aira praecox L. Sp. PI. 65. 1753
Agrostis praecox Salisb. Prodr. 24. 1796. (Based on Aira praecox L.)
Arena praecox Beauv. Agrost. 89, 154. 1812. (Based on Aira praecox L.)
Trisetum praecox Dum. Obs. Gram. 122. 1823. (Based on Aira praecox L.)
Airopsis praecox Fries, Mant. 3: 180. 1842. (Based on Aira praecox L.)
Caryophyllea praecox Opiz, Seznam 27. 1852. (Based on Aira praecox L.)
Fussia praecox Schur, Enum. PI. Transsilv. 754. 1866. (Based on Aira praecox L.)
Airella praecox Dumort. Bull. Soc. Bot. Belg. 7: 68. 1868. (Based on Aira praecox L.)
Salmasia praecox Bubani, Fl. Pyren. 4: 316. 1901. (Based on Aira praecox L.)
Aspris praecox Nash, in Britt. & Brown, III. Fl. ed. 2. I: 215. 1913. (Based on Aira praecox L.)
Culms tufted, usually erect, glabrous, 10-20 cm. tall; sheaths glabrous, striate; ligule pointed, thin, scaberulous, 2-3 mm. long; blades flat, folded, or more or less involute, scaberulous, mostly 1-3 cm. long and less than 1 mm. wide; panicle narrow, dense, 1-3 cm. long, the axis scaberulous, the branches short, scabrous, appressed; spikelets green or yellowish; glumes compressed, acute, scaberulous, 3.5-4 mm. long, a little longer than the florets; lemmas acuminate, scaberulous toward the bisetose summit, about 3 mm. long, the callus-hairs very short; awn attached about 0.7 mm. above the base of the lemma, geniculate, the lower part brown and twisted, the upper part yellow and straight, about 2 mm. long.
Typb locality: Europe.
Distribution: Sandy open ground along the coast. New Jersey to Virginia; Vancouver to California; also in Europe.

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 basal, below middle of stem, Leaves conspicuously 2-ranked, distichous, Leaves sheathing at base, Leaf sheath mostly open, or loose, Leaf sheath smooth, glabrous, Leaf sheath and blade differentiated, Leaf blades very short, 0.5-2 cm long, Leaf bla des linear, Leaf blades very narrow or filiform, less than 2 mm wide, Leaf blade margins folded, involute, or conduplicate, Leaf blades mostly glabrous, Leaf blades scabrous, roughened, or wrinkled, Ligule present, Ligule an unfringed eciliate membrane, Inflorescence terminal, 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, Flowers bisexual, Spikelets pedicellate, Spikelets laterally compressed, Spikelet less than 3 mm wide, Spikelets with 2 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 equal to or longer than adjacent lemma, Gl ume equal to or longer than spikelet, Glumes keeled or winged, Glumes 1 nerved, Glumes 3 nerved, Lemma coriaceous, firmer or thicker in texture than the glumes, Lemma 5-7 nerved, Lemma glabrous, Lemma rugose, with cross wrinkles, or roughened, Lemma apex dentate, 3-5 fid, Lemma distinctly awned, more than 2-3 mm, Lemma with 1 awn, Lemma awn less than 1 cm long, Lemma awn subapical or dorsal, Lemma awn once geniculate, bent once, Lemma margins thin, lying flat, Lemma straight, Callus or base of lemma evidently hairy, Callus hairs shorter than lemma, Palea present, well developed, Palea membranous, hyaline, Palea shorter than lemma, Palea 2 nerved or 2 keeled, Stamens 3, Styles 2-fid, deeply 2-branched, Stigmas 2, Fruit - caryopsis, Caryopsis white, Caryopsis ellipsoid, longitudinally grooved, hilum long-linear.

Aira praecox is a species of grass known by several common names, including early hair-grass, yellow hairgrass and spike hairgrass. It is native to Europe, where it is found in dry, sandy places, on rocky outcrops, and in heath grassland. It also grows in North America as an introduced species, where it can be found on the east and west coasts in sandy or rocky areas, such as beaches and roadsides. This is a tuft-forming annual grass growing up to about 10 to 15 centimeters in maximum height.: 1073  The thin, narrow leaves are located at the base of the stem, and are typically 0.3–2 millimeters wide. It bears small, tightly congested inflorescences of purple-tinted green bisexual spikelets.

It is an annual, forming low and small but numerous tufts. It flowers from April to June.

Certain moths and butterflies, including the Grayling butterfly and the Coast Dart moth, feed on it as larvae.