Poaceae

Agrostis

Intermountain Flora, v. 6, p. 273

• 1. Palea well developed, 0.5-2 mm long, 1/2 to 2/3 as long as the lemma.
• 2. Anthers (0.6)-0.8-1.4 mm long.
• 3. Panicles usually closing after anthesis, the branches floriferous from the base; blades 2-6 mm broad. Agrostis stolonifera

Agrostis stolonifera	Agrostis stolonifera	Agrostis stolonifera	Agrostis stolonifera	Agrostis stolonifera

• 3' Panicles remaining open after anthesis, the branches naked at the base; blades 1-2.5-(3) mm broad; rare in Utah, if present at all. Agrostis capillaris = Agrostis tenuis

Agrostis capillaris	Agrostis capillaris	Agrostis capillaris

• 2' Anthers 0.3-0.7 mm long.
• 4. Lemma 0.8-1.2 mm long; glumes scabrous over the back; panicles compact, the branches spikelet-bearing to the base. Polypogon viridis = Agrostis semiverticillata

Polypogon viridis	Polypogon viridis	Polypogon viridis

• 4' Lemma 1.5-2.2 mm long; glumes glabrous or scabrous on the nerve only; panicles often open, the branches rarely spikelet-bearing to the base.
• 5. Plants usually over 1.5 dm tall; panicles (3.5)-5-10 cm long, more or less open at anthesis; rachilla often prolonged behind the palea as a tiny bristle, up to 0.5 mm long.
• 6. Anthers 0.6-1.5 mm long; rachilla prolongation lacking; palea 0.7-1.2 mm long; plants of lower elevations. Agrostis capillaris = Agrostis tenuis

Agrostis capillaris	Agrostis capillaris	Agrostis capillaris

• 6' Anthers 0.5-0.6 mm long; rachilla prolongation behind the palea as a tiny bristle, up to 0.5 mm long; palea 1.2-2 mm long; plants of subalpine and alpine elevations. Agrostis thurberiana
• 5' Plants usually less than 1,5 dm tall; panicles 1.5-5 cm long, often compressed at anthesis; rachilla prolongation lacking or only up to 0.15 mm long. Agrostis humilis

Agrostis humilis	Agrostis humilis	Agrostis humilis	Agrostis humilis

• 1' Palea obsolete or a small nerveless scale, no longer than 0.3 mm and never as much as 1/2 the length of the lemma.
• 7. Anthers 1.2-1.8 mm long; plants strongly rhizomatous. Agrostis pallens = Agrostis diegoensis

Agrostis pallens	Agrostis pallens	Agrostis pallens

• 7' Anthers merely 0.3-0.7 mm long; plants not rhizomatous (sometimes shortly rhizomatous in A. exarata).
• 8. Panicles narrow, contracted, several times as long as broad, at least some branches spikelet-bearing from the base.
• 9. Plants usually less than 2 dm tall; glumes rarely scaberulous over the back, acute, neither aristate nor awn-tipped; leaves mostly less than 2 mm broad. Agrostis variabilis = Agrostis rossiae

Agrostis variabilis	Agrostis variabilis	Agrostis variabilis

• 9' Plants usually more than 2 dm tall; glumes scaberulous over the back, at least basally, often aristate or awn-tipped; leaves rarely less than 2 mm broad. Agrostis exarata

Agrostis exarata var. minor	Agrostis exarata var. minor	Agrostis exarata var. minor	Agrostis exarata var. minor

• 8' Panicles open, often not more than 2 to 3 times as long as broad, the branches naked at the base.
• 10. Plants (2)-3-9 dm tall; spikelets (2.2)-2.5-3.2 mm long; panicles diffuse, the branches forking above the middle. Agrostis scabra

Agrostis scabra	Agrostis scabra	Agrostis scabra

• 10' Plants smaller, 0.5-3-(4) dm tall, spikelets 1.3-2.3-(2.6) mm long; panicles not diffuse, the branches usually forking below the middle.
• 11. Lemma awnless. Agrostis idahoensis

Agrostis idahoensis	Agrostis idahoensis	Agrostis idahoensis

• 11' Lemma awned; reported from Utah but not seen. Agrostis borealis

Agrostis borealis	Agrostis borealis

• 1. Awn straight, 1-2.5-(3) mm long (often absent in C. scopulorum); callus hairs 1.5-3.5 mm long.
• 2. Panicle loose and open; leaves soft. Calamagrostis canadensis

Calamagrostis canadensis	Calamagrostis canadensis	Calamagrostis canadensis

• 2' Panicle more or less contracted; leaves ridgid.
• 3. Glumes 2.5-4 mm long; lemmas 2.2-3.2 mm long; widespread. Calamagrostis stricta = Calamagrostis neglecta

Calamagrostis stricta	Calamagrostis stricta	Calamagrostis stricta

• 3' Glumes 4.2-6 mm long; lemmas 3.5-5 mm long; S Wyoming, Colorado, New Mexico, N Arizona and Utah (Cedar Breaks, Zion Park). Calamagrostis scopulorum

Calamagrostis scopulorum	Calamagrostis scopulorum	Calamagrostis scopulorum

• 1' Awn geniculate, (2.2)-2.5-8 mm long; callus hairs 0.5-1.5 mm long, less than the length of the lemma.
• 4. Awn 4.5-8 mm long, longer than the glumes; glumes 5.5-7.5 mm long. Calamagrostis purpurascens

Calamagrostis purpurascens	Calamagrostis purpurascens	Calamagrostis purpurascens

• 4' Awn 2.2-3.5-(4.5) mm long, included or scarsely extending beyond the glumes; glumes shorter, 3-5 mm long. Calamagrostis rubescens

Calamagrostis rubescens	Calamagrostis rubescens	Calamagrostis rubescens