Agrostis mertensii Trin.

Agrostis borealis Hartm. Handb. Skand. Fl. ed. 3. 17. 1838
? Agrostis rubra L. Sp. PI. 62. 1753. (Identity uncertain.)
Agrostis canina var. aenea Trin.; Bong. Mem. Acad. St.-Petersb. VI. 2: 170. 1832. (Type from
Sitka, Alaska.) Agrostis canina var. melaleuca Trin.; Bong. Mem. Acad. St.-Petersb. VI. 2: 170. 1832. (Type from
Sitka, Alaska.) Agrostis aenea Trin. Mem. Acad. St.-Petersb. VI. 6 2 : 332. 1841. (Based on A. canina var. aenea
Trin.) Not A. aenea Spreng. 1827. Agrostis canina var. tenella Torr. Fl. N. Y. 2: 443. 1843. (Type from northern New York.) Agrostis Pickeringii Tuckerm. Mag. Hort. Hovey 9: 143. 1843. (Type from White Mountains,
New Hampshire.) Agrostis concinna Tuckerm. Mag. Hort. Hovey 9: 143. 1843. (Type from Mount Monroe, White
Mountains, New Hampshire.) Agrostis Pickeringii var. rupicola Tuckerm. Am. Jour. Sci. 45: 42. 1843. (Type from White
Mountains, New Hampshire.) Trichodium concinnum Wood, Class-Book ed. 2. 600. 1847. (Based on Agrostis concinna Tuckerm.) Agrostis exarata var. aenea Griseb. in Ledeb. Fl. Ross. 4: 441. 1853. (Based on A. canina var. aenea
Trin.) Aira labradorica Steud. Syn. Gram. 220. 1854. (Type from Labrador. Steudel describes the
spikelet as 2-flowered, but the type specimen in Paris has but one floret; the description otherwise agrees with the specimen.) Agrostis rubra var. breviaristata Lange, Consp. Fl. Groenl. 158. 1880. (Type from Julianehaab,
Greenland.) Agrostis rubra var. americana Scribn. in Macoun, Cat. Can. PI. 2 5 : 391. 1890. (Based on ".4.
rupestris Chapm. (non All.)," the type from Roan Mountain, North Carolina.) Agrostis novae-angliae Vasey, Contr. U. S. Nat. Herb. 3: 76. 1892. (Type from Mount Washington,
New Hampshire, Pringle.) Not A. novaeangliae Tuckerm. Agrostis rubra var. alpina MacM. Metasp. Minn. Valley 65. 1892. (Based on A. canina var.
alpina Oakes, a name only, but other synonyms cited show that the name belongs here.) Agrostis paludosa Scribn. Bull. U. S. Dep. Agr. Agrost. 11: 49. 1898. (Type from Blanc Sablon,
Labrador.) Agrostis borealis var. macrantha Eames, Rhodora 11: 88. 1909. (Type from Blow-me-down
Mountains, Newfoundland, the spikelets abnormal.) Agrostis Bakeri Rydb. Bull. Torrey Club 36: 532. 1909. (Type from Pagosa Peak, Colorado,
Baker 150.) Agrostis borealis var. paludosa Fernald, Rhodora 35: 207. 1933. (Based on A. paludosa Scribn.)
Perennial; culms erect or sometimes geniculate at base, cespitose, glabrous, 20-60 cm. tall or, in alpine or high northern plants, dwarf; sheaths glabrous; ligule 1-2 mm. long; blades flat or more or less involute, glabrous or somewhat scabrous, 5-10 cm. long, mostly less than 1 mm. wide, in large lax plants as much as 3 mm. wide; panicle pyramidal, 5-15 cm. long, the axis and branches glabrous or more or less scabrous, the lower whorled, spreading, naked below, mostly 1-4 cm. long; glumes 2.5-3 mm. long, acute, somewhat scabrous on the keels; lemma a little shorter than the glumes, awned from about the middle, the awn usually bent and exserted, sometimes straight and included, rarely wanting; palea minute or obsolete.
Type locality: Sweden.
Distribution: Rocky slopes and moist banks at high altitudes and latitudes, Newfoundland and Greenland to Alaska, and southward to the high mountains of New England and New York; West Virginia; summit of Roan Mountain, North Carolina; and in the Rocky Mountains to Colorado; also in northern Europe.

Perennials, Terrestrial, not aquatic, Stems nodes swollen or brittle, Stems erect or ascending, Stems geniculate, decumbent, or lax, sometimes rooting at nodes, 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 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 an open panicle, openly paniculate, branches spreading, Inflorescence solitary, with 1 spike, fascicle, glomerule, head, or cluster per stem or culm, Inflorescence branches more than 10 to numerous, Lower panicle branches whorled, Flowers bisexual, Spikelets laterally compressed, Spikelet less than 3 mm wide, Spikelets with 1 fertile floret, 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 cle arly present, Glumes equal or subequal, Glumes equal to or longer than adjacent lemma, Glume equal to or longer than spikelet, Glumes 1 nerved, Lemmas thin, chartaceous, hyaline, cartilaginous, or membranous, Lemma 5-7 nerved, Lemma glabrous, Lemma apex truncate, rounded, or obtuse, 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 awns straight or curved to base, Lemma awn once geniculate, bent once, Lemma margins thin, lying flat, Lemma straight, Stamens 3, Styles 2-fid, deeply 2-branched, Stigmas 2, Fruit - caryopsis, Caryopsis ellipsoid, longitudinally grooved, hilum long-linear.

Agrostis mertensii is a species of grass belonging to the family Poaceae.

It has almost cosmopolitan distribution.