Agrostis mertensii
Agrostis rossiae
agrostide de Mertens, Merten's bentgrass, northern bent, northern bentgrass
Ross' bent
(5)10-40 cm, erect, with 2-4 nodes.
4-20 cm.
smooth, upper sheaths inflated;
ligules (0.6)1-1.5 mm, dorsal surfaces scabrous, apices truncate to rounded, lacerate to erose-ciliolate;
blades 1-2.5 cm long, 1-2 mm wide, flat or folded.
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.
(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.
1.5-6 cm long, 0.4-2 cm wide, initially lanceolate, becoming ovate and diffuse, bases sometimes enclosed in the upper sheaths;
branches 1-3 cm, erect to spreading, scabrous;
pedicels 0.5-6.3 mm.
lanceolate to narrowly ovate, dark brown or purplish.
ovate, green, slightly to strongly tinged with 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.
equal, 2-2.5 mm, 1-veined, acuminate;
lower glumes scabrous on the midvein;
upper glumes smooth or scabrous on the midvein;
callus hairs to 0.1 mm, sparse;
lemmas 1.3-1.7 mm, scabrous, translucent to opaque, 5-veined, veins mostly obscure, apices truncate, entire, erose, or the veins excurrent to about 0.12 mm, unawned;
paleas to 0.2 mm, thin;
anthers 3, 0.5-0.9 mm, often retained at the apices of the caryopses.
1.4-2 mm;
endosperm solid.
1.2-1.5 mm;
endosperm semisoft.
= 56 [reports of 2n = 42 are for Agrostis scabra].
= unknown.
Agrostis mertensii
Agrostis rossiae
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 rossiae is a rare species, originally known only from alkaline soils near hot springs in Yellowstone National Park, Wyoming. Tercek et al. (2003) showed that somewhat morphologically similar plants of A. scabra found around hot springs in Yellowstone and Lassen Volcanic national parks, and of A. pauzhetica Prob. found around hot springs on the Kamchatka Peninsula, Russia, are closely related to A. rossiae. They recommended, however, that the three be treated as separate species until more information has been obtained.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
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