Agrostis mertensii
Agrostis variabilis
agrostide de Mertens, Merten's bentgrass, northern bent, northern bentgrass
alpine bent, mountain bent, mountain bent grass, mountain redtop, variable bentgrass
(5)10-40 cm, erect, with 2-4 nodes.
5-30 cm, erect, sometimes geniculate at the base, with 2-5(7) nodes.
mostly basal or basal and cauline, basal leaves persistent;
sheaths smooth or scabrous;
ligules 0.7-3.3 mm, scabridulous or smooth, usually rounded, sometimes acute or truncate, erose, sometimes lacerate;
blades 2.5-13 cm long, 0.5-3 mm wide, usually flat, occasionally involute or folded.
mostly basal, forming dense tufts;
sheaths smooth;
ligules (0.7)1-2.8 mm, dorsal surfaces usually scabridulous, sometimes smooth, apices rounded to truncate, lacerate to erose;
blades 3-7 cm long, 0.5-2 mm wide, flat, becoming folded or involute.
(2)3-10 cm long, (0.5)1.5-5 cm wide, widely ovate to lanceolate, usually open, exserted from the upper sheaths at maturity, lowest node with (1)2-5 branches;
branches erect, not capillary, readily visible, smooth or sparsely scabridulous, branched above midlength, spikelets in the distal 1/2 or beyond, lower branches (1.5)2-4 cm;
pedicels 0.4-6.4 mm.
(1)2.5-6 cm long, 0.3-1.2(2) cm wide, cylindric to lanceolate, usually dense, exserted from the upper sheaths at maturity, lowest node with 1-5 branches;
branches usually scabridulous, sometimes smooth, ascending to erect, branching at or near the base and spikelet-bearing to the base, to branching in the distal 2/3, lower branches 0.5-1.5 cm;
pedicels 0.4-2.8(4.3) mm.
lanceolate to narrowly ovate, dark brown or purplish.
ovate to lanceolate, greenish purple.
subequal, 2-4 mm, elliptical to lanceolate, midveins scabrous to scabridulous, at least distally, 1-veined, acute;
callus hairs to 0.4 mm, sparse;
lemmas 1.6-2.6 mm, smooth or scabridulous, translucent to opaque, 5-veined, veins prominent to obscure, apices acute, entire or erose, awned from just below midlength, awns (2)3-4.4 mm, geniculate, exserted, persistent;
paleas absent, or to 0.1 mm and thin;
anthers 3, 0.5-0.8 mm, usually shed at anthesis.
subequal to equal, 1.8-2.5 mm, smooth, or scabrous on the keel and sometimes elsewhere, 1-veined, acute to acuminate;
callus hairs to 0.2 mm, sparse to abundant;
lemmas 1.5-2 mm, smooth, translucent, (3)5-veined, veins usually prominent distally, sometimes obscure throughout, apices acute, entire, usually unawned, rarely awned, awns to 1(2.8) mm, arising beyond the midpoint, usually not reaching the lemma apices;
paleas to 0.2 mm, thin;
anthers 3, 0.4-0.7(1) mm.
1.4-2 mm;
endosperm solid.
1-1.3 mm;
endosperm soft.
= 56 [reports of 2n = 42 are for Agrostis scabra].
= 28.
Agrostis mertensii
Agrostis variabilis
Agrostis mertensii grows on banks and gravel bars in river and lake valleys, and on open grasslands and rocky slopes of mountains and cliffs. It has a circumboreal distribution. In the Flora region, it extends from Alaska across Canada to Newfoundland and Greenland, south in the mountains to Wyoming and Colorado in the west, and West Virginia, Tennessee, and North Carolina in the east. It also grows in arctic Europe, Scandinavia, the mountainous regions of Mexico, and northwestern South America, where some unusually robust specimens have been somewhat dubiously referred to this species.
Agrostis mertensii is frequently confused with dwarf, awned forms of A. scabra (p. 646), but has larger spikelets, more culm nodes, larger anthers, slightly wider, flatter leaves, and panicles that are less expanded and less than lh the culm length. Agrostis mertensii is also often confused with A. idahoensis (p. 649), but A. mertensii tends to grow in better-drained habitats. Agrostis mertensii differs from A. anadyrensis (see next) in being less robust, having narrower, less abundant basal leaves, smaller panicles, and minor differences in the insertion of the awns on the lemmas. In addition, the panicle branches are smooth to weakly scabrous, contrasting with the branches of A. anadyrensis, which are strongly scabrous, with long acicules throughout their length.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
Agrostis variabilis grows in alpine and subalpine meadows and forests and on talus slopes, at elevations up to 4000 m, from British Columbia and Alberta south to California and New Mexico. It can appear similar to dwarf forms of Podagrostis humilis (p. 694), but differs from that species in not having paleas.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
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