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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 , spikelets 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; ligule generally < 3 mm (except Agrostis gigantea)

5. Palea 0 or minute, << lemma

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

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

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

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

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

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

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

1' Rhizomes or stolons 0; annual or perennial herb

9. Lemma awned from back or near tip

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

11. Inflorescence generally oblong to lanceolate in outline, 1° branches generally ascending

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

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

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

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

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

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

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

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

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

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

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

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

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

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

18' Back of glume ± glabrous (keel fine-scabrous); palea ± 0.3 mm; ligule 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 spikelets

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

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

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

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

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

21' Lemma 1.5–2 mm, awn 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 blade 2–10 mm wide; lemma 1.5–2 mm; floret callus minutely hairy; coastal bluffs ..... A. densiflora (3)

24' Lf blade 0.3–1.5 mm wide; lemma 1.1–1.5 mm; floret callus glabrous; vernal pools ..... A. lacuna-vernalis

23' Palea 0 or < 1/3 lemma

25. Leaf blade 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 blade generally 2–7 mm wide, generally flat

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

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

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, spikelets 0 on proximal 1/2

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

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

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

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

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

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

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

33. Palea 0 or minute, << lemma

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

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

33' Palea >= 1/2 lemma

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

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

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

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

 

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