Plant Species of San Jacinto Mountain: High-Elevation Grass Species

This is just a very rough draft page to list the higher-elevation grass species of San Jacinto Mountain, for Tahquitz Valley and above (above the elevation of Caramba at 6600 feet), and show some pix of them.

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List of Genera and Key
Species Links

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List of Genera and Key

There are 11 genera found in this area:

• Achnatherum
• Agrostis
• Bromus
• Deschampsia
• Digitaria
• Elymus / Elytrigia / Leymus (often all combined into Elymus)
• Glyceria
• Muhlenbergia
• Phleum
• Poa
• Trisetum

Two of the genera have just one species present in each, which are easily recognized by their appearance:

• Phleum alpinum, mountain timothy, found only in wet meadows, inflorescence dense, ovoid, branches not apparent (Calphotos picture)

• Digitaria sanguinalis, crabgrass, non-native, annual, inflorescence palmate, only one record, from Tahquitz Meadow (Calphotos picture)

The other nine genera can be easily keyed out by simply counting the number of florets / lemmas per spikelet, and noting whether the lemmas are awned or not:

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Key to other nine genera

1. floret 1

2. awn > 15 mm.........Achnatherum
2'. awn < 4 mm

3. glumes > lemma.........Agrostis
3'. glumes < lemma.........Muhlenbergia

1'. florets 2-11

4. leaf blade thread-like, width 0.5-1 mm; infl narrow; florets 2; glumes > lemmas.........Deschampsia elongata
4'. leaf blade gen flat, width 0.5-17 mm; infl narrow to very wide; florets 2-11; glumes < lemmas

5. lemma not awned

6. Pl 6-15 dm; lf blade 4-12 mm wide; lemma rounded on back, strongly 5-11 veined, veins not converging to tip; glumes 0.8-1.5 mm long.........Glyceria
6'. Pl 1.5-10 dm; lf blade 0.5-5 mm wide; lemma gen compressed, weakly 5 veined, veins converging to tip.........Poa

5' lemma awned

7. awn attached below lemma tip; florets gen 2-3.........Trisetum
7'. awn from lemma tip; florets 2-11

8. infl spikelike, florets 1-3 per node.........Elymus / Elytrigia / Leymus
8'. infl open, often nodding or drooping, florets 1 per node.........Bromus

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glumes > lemmas means the glumes are longer than the lemmas, and hide at least the lowermost lemma entirely.

glumes < lemmas means the glumes are shorter than the lemmas, and never hide the uppermost portion of the lowermost lemma.

Species Links

• Agrostis exarata
• Digitaria sanguinalis, crabgrass, non-native, annual, inflorescence palmate, only one record, from Tahquitz Meadow (Calphotos picture)
• Muhlenbergia andina
• Phleum alpinum, mountain timothy, found only in wet meadows, inflorescence dense, ovoid, branches not apparent (Calphotos picture)
• Poa pratensis
• Trisetum canescens

Go to:

• Plant Species of San Jacinto Mountain

Copyright © 2009 by Tom Chester.
Commercial rights reserved. Permission is granted to reproduce any or all of this page for individual or non-profit institutional internal use as long as credit is given to me at this source:
http://tchester.org/sj/species/grasses.html
Comments and feedback: Tom Chester
Updated 1 September 2009.