Agrostis mertensii
Agrostis perennans
agrostide de Mertens, Merten's bentgrass, northern bent, northern bentgrass
agrostide perennant, autumn bent, autumn bentgrass, upland bent, upland bentgrass
(5)10-40 cm, erect, with 2-4 nodes.
20-80 cm, erect, sometimes rooting at the lower nodes, with 3-10 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.
usually mostly cauline, basal leaves withering at anthesis;
sheaths usually smooth, sometimes scabridulous, ligules (0.7)1.5-7.3 mm, dorsal surfaces scabrous, apices acute to truncate, erose to lacerate, often ciliolate;
blades 6-20 cm long, 2-5 mm wide, flat, lax to stiff, cauline blades as substantial as the basal blades.
(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.
10-25 cm long, 2.5-11 cm wide, broadly ovate, open, bases usually exserted, sometimes enclosed in the upper sheaths at maturity, lowest node with (1)3-11(13) branches;
branches scabridulous, capillary, wide-spreading, branching above midlength, spikelets somewhat aggregated towards the ends of the branches, lower branches 3-7 cm;
pedicels 1-7.3 mm, spreading;
secondary panicles sometimes present in the leaf axils.
lanceolate to narrowly ovate, dark brown or purplish.
lanceolate to narrowly ovate, green to tawny.
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.
unequal, 1.8-3.2 mm, lower glumes longer than the upper glumes.
1.4-2 mm;
endosperm solid.
1.1-1.9 mm;
endosperm liquid.
-veined, veins scabrous, acuminate to acute;
callus hairs to 0.3 mm, abundant;
lemmas 1.3-2.2 mm, smooth or scabridulous, translucent, 5-veined, veins prominent to obscure, apices acute to more or less truncate, entire or minutely denticulate, usually unawned, rarely awned from near midlength, awns to 2 mm, straight, not exserted;
paleas absent, or to 0.1 mm and thin;
anthers 3, 0.4-0.9 mm.
= 56 [reports of 2n = 42 are for Agrostis scabra].
= 42.
Agrostis mertensii
Agrostis perennans
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 perennans grows along roadsides and in fields, fens, woodlands, and periodically inundated stream banks. It is widespread and common in eastern North America; it also grows from central Mexico to central South America. There are old records from Oregon and Washington, but A. perennans does not appear to be established in western North America. It is more tolerant of shade and moisture than Agrostis scabra (p. 646), from which it differs in its later flowering, leafier culms, and its basal leaves that usually wither by anthesis.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
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