Silver Hairgrass

Foodplant / sap sucker
adult of Neides tipularius sucks sap of Aira caryophyllea

This pioneer of dry, open places is now widespread in temperate regions.

Culms solitary or tufted, erect or slightly geniculate, very slender, 5–30 cm tall, scabrid. Leaf sheaths scaberulous; leaf blades narrowly linear to filiform, 1–5 cm, 2–3 mm wide; ligule lanceolate, 1–4 mm, acute becoming lacerate. Panicle open, ovate in outline, up to 10 cm; branches 2–5 cm, capillary, scabrid, bearing spikelets in clusters toward tips; pedicels 2–4 mm, up to twice spikelet length, a pear-shaped swelling below spike-let. Spikelets ovate-oblong in outline, 2–3.5 mm, shining, silvery-gray or tinged purplish; glumes as long as spikelet, keel scaberulous; florets both awned; lemmas brown, 3/4 length of glumes, scabrid, narrowed to 2-toothed apex; awn 2.5–4 mm, arising from lower 1/3 of lemma. Anthers 0.3–0.6 mm.

W Xizang [India, Russia; N Africa, SW Asia, Europe; introduced in North and South America and Australia].

Dry grassy places in mountains; ca. 3600 m.

Aira caryophyllea is native to Europe, Asia and North Africa, with particular concentration in southwestern Europe; however, the species is presently a widespread alien species in North America, South America and Australia. Typical habitats are dry mountain grassland, coastal prairies and other open ecosystems. The species prefers sandy soils, has an affinity for waste spaces.

Silver hairgrass is an annual species that does not exceed one meter in height. The common name derives from the silvery appearance of the early season grass, although in the later season it turns whitish.

Aira caryophyllea L. Sp. PI. 66. 1753
Avena caryophyllea Wiggers, Prim. Fl. Holsat. 10. 1780. (Based on Aira caryophyllea L.) Agroslis caryophyllea Salist). Prodr. 25. 1796. (Based on Aira caryophyllea L.) Airopsis caryophyllea Fries, Mant. 3: 180. 1842. (Based on Aira caryophyllea L.) Caryophyllea airoides Opiz, Seznam 27. 1852. (Bused on Aira caryophyllea L.) Fussia caryophyllea Schur, Enum. PI. Transsilv. 754. 1866. (Based on Aira caryophyllea h) Airella caryophyllea Dumort. Bull. Soc. Bot. Belg. 7; 68. 1868. (Based on Aira caryophyllea L.) Salmasia vulgaris Bubani, Fl. Pyren. 4: 316. 1901. (Based on Aira caryophyllea L.) Aspris caryophyllea Nash, in Britt. & Brown, 111. I'l. ed. 2. 1: 214. 1913. (Based on Aira caryophyllea L.)
Culms solitary or in small tufts, erect, very slender, glaljrous, 10-30 cm. tall; sheaths slightly retrorsc-scaberulous; ligule pointed, lacerate, 5 mm. long; blades glabrous or scaberulous, very narrow, short; panicle open, 2-7 cm. long, the axis angled, glabrous or scaberulous, the branches capillary, ascending or spreading, scabrous, the spikelets clustered toward the ends; glumes broad, rather abruptly acute, very finely scabrous on the keel, the margins finely toothed, about 3 mm. long; lemmas about three fourths as long as the glumes, acute, bisetose, both awned from below the middle, the awn geniculate, about 3 mm. long.
Type loc^uity: Europe.
Distribution: Open dry ground on the coastal plain, Massachusetts to Florida and Louisiana; Ohio; common on the Pacific Coast from British Columbia to California; also in southern South America, Europe, and Africa.

Annuals, Terrestrial, not aquatic, Stems nodes swollen or brittle, Stems erect or ascending, Stems geniculate, decumbent, or lax, sometimes rooting at nodes, Stems solitary, 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 mostly cauline, 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 linear, Leaf blades very narrow or filiform, less than 2 mm wide, Leaf blades 2-10 m m 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, Ligule a fringed, ciliate, or lobed membrane, Inflorescence terminal, Inflorescence an open panicle, openly paniculate, branches spreading, Inflorescence a contracted panicle, narrowly paniculate, branches appressed or ascending, Inflorescence solitary, with 1 spike, fascicle, glomerule, head, or cluster per stem or culm, Inflorescence with 2-10 branches, Flowers bisexual, 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 eq ual to or longer than adjacent lemma, Glume 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 3 nerved, Lemma 5-7 nerved, Lemma glabrous, Lemma apex acute or acuminate, 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, 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 caryophyllea is a species of grass known by the common name silver hairgrass. It's a species of bunchgrass that is native to Europe, Africa, and Asia. It has been introduced to other continents, including North America, where it is naturalized and common.

Aira caryophyllea is a light green grass with a silvery sheen on its spikelets before it dries and becomes straw-colored to white. The spikelets are borne on a spreading panicle inflorescence.