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Yavapai County Native & Naturalized Plants

Agrostis exarata - spike bentgrass

Synonyms: Agrostis aenea, A.alaskana, A.ampla, A.asperifolia, A.exarata ssp. minor, Agrostis exarata var. minor (see USDA for more)

Other Common Names: spiked bent, spike red top, western bentgrass

Plant Form:Grass

Family: Poaceae

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Max Licher @, Usage Rights: Creative Commons Attribution-ShareAlike (CC BY-SA)
  Grass Description -   Glossary of Grass Terminology

Origin: Native    Season: Warm
Habitat Description: Moist soils along streams and in canyons and meadows.
Plant Communities: Riparian
Elevation: 3500 - 10000 feet

General Description

Desc: Tufted perennial, sometimes rhizomatous but not stoloniferous with stems up to 40 inches tall, erect or drooping at the base. Leaves mostly basal below the middle of the stems.
Identification notes: Tall bunchgrass, may be rhizomatous; blades flat or folded, 2 to 8 inches long; ligules 1/16 to 5/16 inch long and lacerate; seedhead spikelike, short appressed branches bear one-flowered spikelets to the base; glumes nearly equal.
Grass Type: Perennial bunchgrass  Rhizomes: Y  Stolons: N
Large Dense Clump (> 2 feet): N  Bushy (highly branched): N
Height with Seedheads: Greater than 36 inches
Seedhead Structure: Branched - contracted  Seedhead Droops: N
Flowering Period: May - Oct

Flower Characteristics

Number of Flowers per Spikelet: One-flowered  Spikelets One-sided: N
Awns: Less than 1/4 inch   Three Awns: N  Awns Bent: N

Flower and Seedhead Notes: Seedhead is a dense slender spike, bearing spikelets to the base. Seedhead is 4 to 10 inches tall with branches that are appressed or ascending. Spikelets bear a single fertile floret and are greenish or purplish.

Vegetative Characteristics

Blade Hairy: Y  Blade with White Margin: N  Blade Cross Section: Flat or folded  
Blade Notes: Blades are ascending to spreading up to 8 inches long, 1/4 inch wide. Blade margins are flat or folded inward. Leaf blades are mostly smooth but may be hairy or rough.
Sheath Hairy: Y  Tuft of Hairs Top of Sheath or Collar: N  Ligules: Membranous
Auricles (Ear-like lobes at base of blades): N
Vegetative Notes: Sheath may be smooth or slightly hairy. Ligule is a hairless membrane.

Forage Value: Spike bentgrass is highly palatable and rated as good forage for cattle, horses, and elk, and fair to good for sheep and deer.

  Arizona Cooperative Extension
Yavapai County
840 Rodeo Dr #C
Prescott, AZ 86305
(928) 445-6590
Version 8.0  
Last Updated: Nov 21, 2021
Content Questions/Comments: Email Mary Barnes  
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