Agrostis exarata |
Poaceae subfam. pooideae |
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bentgrass, spike bent, spike bent grass |
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Habit | Plants perennial; usually cespitose, sometimes rhizomatous, not stoloniferous. | Plants annual or perennial; sometimes matlike, sometimes cespitose, sometimes stoloniferous, sometimes rhizomatous. | ||||||||||||||||||||||||||||||||||||
Culms | 8-100 cm, erect or decumbent at the base, sometimes rooting at the lower nodes, with (2)3-6(8) nodes. |
usually hollow, sometimes solid. |
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Leaves | mostly cauline; sheaths smooth or slightly scabrous; ligules (1)1.7-8(11.2) mm, dorsal surfaces scabrous, apices truncate to obtuse, lacerate to erose; blades 4-15 cm long, 2-7 mm wide, flat. |
distichous; sheaths usually open to the base, varying to closed for nearly their full length; auricles present or absent; abaxial ligules absent; adaxial ligules scarious or membranous, sometimes puberulent or scabridulous, usually not ciliate, cilia sometimes shorter than the base; pseudopetioles rarely present; blades usually linear, sometimes broadly so, venation parallel; cross sections non-Kranz, mesophyll nonradiate, adaxial palisade layer absent, fusoid and arm cells usually absent; midribs usually simple; adaxial bulliform cells present; stomates with parallel-sided subsidiary cells; epidermes usually lacking bicellular microhairs, sometimes with unicellular microhairs, papillae usually absent, when present, rarely more than 1 per cell. |
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Panicles | (3)5-30 cm long, 0.5-4 cm wide, contracted, spikelike, oblong, or lanceolate, usually dense, rarely more open, sometimes interrupted near the base, bases usually exserted, rarely enclosed by the upper sheaths at maturity, lowest node with 1-5 branches; branches scabrous, ascending to appressed, spikelet-bearing to or near the base, usually hidden by the spikelets, spikelets crowded, lower branches 1-2(4) cm; pedicels 0.2-4.3 mm. |
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Inflorescences | usually terminal, panicles, spikes, or racemes, usually ebracteate; disarticulation usually below the florets, sometimes below the glumes, at the rachis nodes, or at the inflorescence bases. |
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Spikelets | lanceolate to narrowly ovate, greenish to purplish. |
usually bisexual, infrequently unisexual or mixed, usually laterally compressed or not compressed, occasionally dorsally compressed, with 1-30 sexual florets, distal floret(s) often reduced, infrequently spikelets with 1-2 reduced or staminate basal florets and a single terminal sexual floret. |
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Glumes | subequal to equal, 1.5-3.5 mm, scabrous on the midvein and sometimes on the back, 1(3)-veined, acute, elongate-acuminate, with an awnlike tip to 1 mm; callus hairs to 0.3 mm, sparse to abundant; lemmas 1.2-2.2 mm, smooth, translucent to opaque, 5-veined, veins prominent distally or obscure throughout, apices acute, entire or toothed, teeth no more than 0.12 mm, unawned or awned from above midlength, awns to 3.5 mm, straight or geniculate; paleas absent or to 0.5 mm; anthers 3, 0.3-0.6 mm. |
usually 2, upper or lower glumes sometimes absent, rarely both glumes absent; lemmas without uncinate hairs, awned or not, awns single, basal to apical; paleas usually well-developed, sometimes reduced or absent; lodicules 2(3), usually lanceolate and broadly membranous distally, rarely truncate and fleshy, usually not veined or obscurely veined, sometimes distinctly veined, sometimes ciliate; anthers (1, 2)3; ovaries glabrous or sometimes hairy distally, sometimes with an apical appendage; haustorial synergids absent; styles (1)2 (-4), bases close together, sometimes fused. |
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Caryopses | 0.9-1.2 mm; endosperm solid or soft. |
hila linear, elliptic, ovate, or punctate; endosperm usually hard, sometimes soft or liquid, with or without lipids, starch grains compound or simple; embryos less than 1/2 the length of the caryopses; epiblasts usually present; scutellar cleft usually absent; mesocotyl internode usually absent; embryonic leaf margins overlapping, x = 7, 10. |
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2n | = 28, 42, 56. |
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Agrostis exarata |
Poaceae subfam. pooideae |
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Distribution |
AK; AZ; CA; CO; ID; KY; MT; NE; NM; NV; OK; OR; SD; TX; UT; VT; WA; WY; AB; BC; NT; SK; YT
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Discussion | Agrostis exarata is common and widely distributed in western North America, usually growing in moist ground in open woodlands, river valleys, tidal marshes, and swamp and lake margins; it also grows in dry habitats such as grasslands and shrublands. It extends from Alaska into Mexico, and is also found in Kamchatka and the Kuril Islands. Eastern North American records probably reflect introductions. It readily colonizes roadsides and bare soil, and exhibits ecological and developmental flexibility. Agrostis exarata is recognized here as a single, variable species that includes what others have treated as distinct species or varieties. Cytotaxonomic study might clarify the basis of the observed variation. Agrostis exarata appears to be related to A. densiflora (see below). (Discussion copyrighted by Flora of North America; reprinted with permission.) |
The subfamily Pooideae includes approximately 3300 species, making it the largest subfamily in the Poaceae. It reaches its greatest diversity in cool temperate and boreal regions, extending across the tropics only in high mountains. The circumscription and relationships of tribes within the Pooideae are unsettled (see, for example, Catalan et al. 1997, 2004; Soreng and Davis 1998). In this flora, some previously recognized tribes have been combined with the Poeae. Recognition of some of these as subtribes is well supported; among these is the Hainardieae Greuter (which, at the subtribal level, is called the Parapholiinae Caro). Members of other traditional tribal groupings, such as the Aveneae Dumort., appear to be widely dispersed within the Poeae sensu lato. Further work will probably support the division of the expanded Poeae into additional tribes; there is as yet no clear indication as to what the boundaries of such tribes should be. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
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Key |
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Source | FNA vol. 24, p. 651. | FNA vol. 24, p. 57. | ||||||||||||||||||||||||||||||||||||
Parent taxa | Poaceae > subfam. Pooideae > tribe Poeae > Agrostis | Poaceae | ||||||||||||||||||||||||||||||||||||
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Synonyms | A. longiligula var. australis, A. longiligula, A. exarata var. purpurascens, A. exarata var. pacifica, A. exarata var. monolepis, A. exarata var. minor, A. exarata subsp. minor, A. ampla, A. alaskana | |||||||||||||||||||||||||||||||||||||
Name authority | Trin. | Benth. | ||||||||||||||||||||||||||||||||||||
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