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Vascular Plants of California
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Key to Agrostis

View taxon page for Agrostis

(For a list of species in Agrostis, use the above link.)

Jepson Manual glossary definitions can be seen by moving your cursor over words underlined with dots.

1. Rhizomes or stolons well developed, clearly present;  herb

2. Plant from stolons

3. Ligule 0.5–2 mm, generally wider than long; stolons < 5 cm; inflorescence widely  in outline, 1° branches mostly  not crowded ..... A. capillaris (3)

3' Ligule 2–5 mm, longer than wide; stolons 5–100 cm; inflorescence  to  in outline, 1° branches generally all  overlapping, crowded ..... A. stolonifera

2' Plant from rhizomes

4. Floret callus hairs 1.5–2 mm, generally > 1/2  4–7 mm ..... A. hallii (3)

4' Floret callus hairs generally minute, sparse, or 0;  generally < 3 mm (except Agrostis gigantea)

5. Palea 0 or minute, << 

6. Proximal   1–6 mm wide;  tip minutely toothed;  < 10 cm; anthers 0.7–1.8 mm ..... A. pallens (3)

6' Proximal   < 1 mm wide;  tip ±  < 5 cm; anthers 0.5–0.7 mm ..... A. variabilis (3)

5' Palea well developed, ± 1/2 to slightly < 

7. Inflorescence ±  in outline, ± open, branches generally  to montane to alpine, 1300–3500 m ..... A. humilis (2)

7' Inflorescence generally  in outline, open, most branches ; open, generally disturbed places, < 2000 m

8. Rhizomes < 5 cm, slender, not clearly scaly;  generally wider than long; inflorescence branches with  on distal 1/2 ..... A. capillaris (3)

8' Rhizomes < 25 cm, ± thick, ± scaly;  longer than wide; inflorescence branches with  ± throughout ..... A. gigantea (2)

1' Rhizomes or stolons 0; annual or  herb

9. Lemma awned from back or near tip

10. Inflorescence open, generally  to  in outline;  not crowded, inflorescence axes clearly visible

11. Inflorescence generally  to  in outline, 1° branches generally 

12. Lemma awned below middle; anthers 1–1.5 mm; proximal  sheaths finely  ..... A. hooveri

12' Lemma awned at or above middle; anthers <= 0.8 mm; proximal  sheaths generally glabrous

13. Proximal inflorescence branches 1–2 cm;  < 3.5 mm, straight to bent;  < 1/3 anthers 0.3–0.6 mm ..... A. exarata (3)

13' Proximal inflorescence branches 2–6 cm;   < 2 mm, straight;  1/5–1/4 lemma; anthers 0.6–0.8 mm ..... A. oregonensis (2)

11' Inflorescence generally  in outline, proximal-most 1° branches distal branches generally 

14. Lemma back  below middle; floret axis prolonged beyond floret ± 1 mm, short-hairy-tufted;  > 1 mm ..... A. avenacea

14' Lemma back glabrous or fine-scabrous; floret axis not prolonged beyond  0 or minute

15. Lemma generally awned near tip,  3–10 mm, wavy; callus hairs < 0.6 mm, denseanther 1, persistent in fruitannual ..... A. elliottiana

15' Lemma awned below middle,  < 2 mm, ± straight; callus hairs << , sparse; anthers 3, deciduous herb ..... A. scabra (2)

10' Inflorescence dense, generally  crowded, overlapping, inflorescence axes not clearly visible

16. 1° inflorescence branches generally > 0.5 cm, often evident at base (except Agrostis blasdalei)

17. Leaf  generally < 1 mm wide, ± inrolled; floret callus glabrousinflorescence base often partly enclosed by  of distal-most anthers 1–2 mm ..... A. blasdalei (2)

17' Leaf  generally 2–10 mm wide, flat; floret callus minutely hairy; inflorescence base not partly enclosed by  of distal-most anthers ± 0.5 mm

18. Back of  fine-scabrous throughout;  0.5–0.7 mm;  1.5–2 mm ..... A. densiflora (3)

18' Back of  ± glabrous (keel fine-scabrous);  ± 0.3 mm;  2.5–4 mm ..... A. exarata (3)

16' 1° inflorescence branches generally < 0.5 cm (< 1.5 cm in Agrostis microphylla), obscured by densely clustered 

19. Lemma teeth 4, two < 1 mm, other two 1–1.5 mm;  awned below middle; callus densely short-hairy ..... A. tandilensis

19' Lemma teeth 0 or 2, equal;  awned at or above middle; callus generally sparsely hairy, hairs minute

20. Lemma awned above middle,  < 3.5 mm, straight;  tips  herb ..... A. densiflora (3)

20' Lemma awned ± at middle,  3.5–10 mm, generally bent;  tips narrowly  to awn-like; annual

21. Lemma 2–4 mm,  8–10 mm ..... A. hendersonii

21' Lemma 1.5–2 mm,  3.5–8 mm ..... A. microphylla

9' Lemma awnless (occasionally short-awned near tip in Agrostis capillaris, from near middle in Agrostis pallens)

22. Spikelets crowded and often overlapping on same branch,  stalks and 2° axes not clearly visible

23. Palea 1/3–2/3 lemma24. Lf  2–10 mm wide;  1.5–2 mm; floret callus minutely hairy; coastal bluffs ..... A. densiflora (3)

24' Lf  0.3–1.5 mm wide;  1.1–1.5 mm; floret callus glabrousvernal pools ..... A. lacuna-vernalis

23' Palea 0 or < 1/3 

25. Leaf  generally < 1 mm wide, generally inrolled or folded

26. Anthers 1–2 mm; inflorescence branches generally < 0.5 cm; coastal habitats < 100 m ..... A. blasdalei (2)

26' Anthers 0.5–0.7 mm; inflorescence branches 0.5–1.5 cm; inland mtns, 1600–4000 m ..... A. variabilis (3)

25' Leaf  generally 2–7 mm wide, generally flat

27. Floret callus hairs 1.5–2 mm, generally slightly > 1/2  ..... A. hallii (3)

27' Floret callus hairs 0 or < 0.5 mm, < 1/2 

28. Proximal inflorescence branches 1–2 cm; anthers 0.3–0.6 mm ..... A. exarata (3)

28' Proximal inflorescence branches 2–5 cm; anthers 0.7–1.8 mm ..... A. pallens (3)

22' Spikelets not crowded, generally well spaced on same branch, axes generally clearly visible

29. 1° inflorescence axes branched 1–2 × above middle,  0 on proximal 1/2

30. Proximal  blades 2–4 mm wide; glumes 2–3 mm;  1/5–1/4 anthers 0.6–0.8 mm ..... A. oregonensis (2)

30' Proximal  blades 0.5–3 mm wide; glumes 1.5–3 mm;  0 or minute, << anthers <= 0.7 mm

31. Leaves  and caulineinflorescence ± 2 × longer than wide; 1° axes ± stiff ..... A. idahoensis

31' Leaves mostly inflorescence ± long as wide; 1° axes flexible, proximal ± arched ..... A. scabra (2)

29' 1° inflorescence axes branched 1–2 × from base upwards,  distributed throughout

32. Floret callus hairs 1.5–2 mm, generally slightly > 1/2 anthers >= 1.5 mm ..... A. hallii (3)

32' Floret callus glabrous or hairs minute, << anthers generally < 1.5 mm (except some Agrostis pallens)

33. Palea 0 or minute, << 

34. Leaf  1–6 mm wide; plants generally 10–70 cm; anthers 0.7–1.8 mm ..... A. pallens (3)

34' Leaf  generally < 1 mm wide; plants 4–30 cm; anthers 0.5–0.7 mm ..... A. variabilis (3)

33' Palea >= 1/2 

35. Inflorescence branches  to anthers < 1 mm; moist to ± dry areas, generally > 1500 m ..... A. humilis (2)

35' Inflorescence branches  to anthers 0.8–1.5 mm; disturbed areas, generally < 1500 m

36. Ligule 0.5–2 mm, generally wider than long; inflorescence branches with  on distal 1/2 ..... A. capillaris (3)

36' Ligule 2–6 mm, longer than wide; inflorescence branches with  ± throughout ..... A. gigantea (2)

 

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Citation for an individual treatment: [Author of taxon treatment] [year]. [Taxon name] in Jepson Flora Project (eds.) Jepson eFlora, [URL for treatment]. Accessed on .

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