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Key to families | Table of families and genera

Specimen numbers are hyperlinked to records in the Consortium of California Herbaria data view where possible. Taxa are hyperlinked to entries in the Jepson Interchange via the "[Online Interchange]" link.



Rosa Cerros-Tlatilpa & Kelly W. Allred

Annual, perennial herb, cespitose. Stem: ascending to erect, generally glabrous (except Aristida californica). Leaf: basal and cauline; basal often tufted; ligule hairy; blade flat or inrolled. Inflorescence: raceme-like or panicle-like; branches spike-like. Spikelet: glumes narrowly lanceolate, thin, 1-veined, awn generally 0; floret 1, breaking above glumes; lemma ± fusiform, hard when mature, 3-veined, tip beak-like or not, awned at tip, awns 3, equal or unequal; palea < lemma, enclosed by lemma, transparent. Fruit: narrowly fusiform.
± 300 species: worldwide, arid warm temperate. (Latin: awn) [Allred 2007 FNANM 25:315–342] Some species noxious weeds.
Unabridged references: [Allred 1992 Great Basin Naturalist 52:41–52]

Key to Aristida

1. Lower stems densely hairy ..... A. californica

1' Lower stems glabrous

2. Annual

3. Glumes 10–22 mm; lemma awns generally 10–70 mm ..... A. oligantha

3' Glumes 3–13 mm; lemma awns 3–20 mm

4. Central awn straight to curved at base ..... A. adscensionis

4' Central awn spirally coiled at base ..... A. dichotoma

2' Perennial herb

5. 1° inflorescence branches spreading at base (upper appressed to ascending in Aristida purpurea var. wrightii)

6. Lower inflorescence branches spreading, upper ascending to appressed ..... A. purpurea var. parishii (2)

6' All inflorescence branches spreading

7. Leaf blade base glabrous; lemma tip much twisted; anthers 0.8–1 mm ..... A. divaricata

7' Leaf blade base sparsely long-hairy; lemma tip slightly twisted or straight; anthers 1–2 mm ..... A. ternipes var. gentilis

5' 1° inflorescence branches appressed to ascending at base (curving or drooping in Aristida purpurea var. purpurea) ..... A. purpurea

8. Awns generally > 40 mm

9. Upper glume generally 16–25 mm; lemma 0.3–0.8 mm wide just below awns, awns 0.2–0.5 mm wide at base ..... var. longiseta

9' Upper glume generally 7–16 mm; lemma 0.1–0.3 mm wide just below awns, awns 0.1–0.3 mm wide at base ..... var. purpurea (2)

8' Awns generally < 40 mm

10. 1° inflorescence branches and spikelet stalks thread-like, curving to drooping, appearing S- or U-shaped ..... var. purpurea (2)

10' 1° inflorescence branches and spikelet stalks generally stiff, straight, generally appressed to ascending (lower spreading in Aristida purpurea var. parishii)

11. Lemma tip, awn base ± 0.1 mm wide at base, awns delicate ..... var. nealleyi

11' Lemma tip, awn base 0.2–0.3 mm wide, awns ± stiff

12. Inflorescence generally 3–15 cm; leaf blade generally 4–10 cm ..... var. fendleriana

12' Inflorescence generally 12–30 cm; leaf blade generally 10–25 cm

13. Inflorescence dense, ± red when young; lower branches with 10–20 spikelets ..... var. parishii (2)

13' Inflorescence ± open, tan to brown when young; lower branches with 2–10 spikelets ..... var. wrightii


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