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Idaho fescue

crinkle-awn fescue

Habit Plants 30–100 cm tall; densely cespitose, glaucous or less often green. Plants (40)60–100(125) cm tall; loosely cespitose, green.
Culms

basal branching intravaginal.

glabrous, 2–4 exposed nodes;

basal branching extravaginal.

Leaves

mostly basal;

sheaths open, glabrous to hairy, usually pale (white, pink, light brown) and lacking contrasting veins, crumbling or somewhat splitting between the veins but not shredding;

blades readily spinning between the fingers;

collars glabrous;

ligules 0.3–0.6 mm;

blades (5)8– 25(35)cm × 0.3–1 mm as folded, conduplicate, usually glaucous, sometimes green;

outer surface scabrous, sometimes with long hairs;

inner surface with hairs about as long as the leaf is thick; flag leaves (1.5)3–7(9.5) cm, usually conduplicate, sometimes loosely rolled.

mainly cauline;

sheaths glabrous to abundantly hairy, splitting between the veins toward the end of the growing season;

collars with sparse long hairs or rarely glabrous;

ligules 0.1–0.5 mm, ciliate;

hairs equaling or longer than the membranous portion;

blades 2–6(10)mm wide; flat; lax;

upper surface with dense; soft; velvety hairs;

lower surface usually glabrous.

Inflorescence(s)

s (5)7– 12(20) cm; open at anthesis; lowest node with 1–2 branches;

branches (5.8)7.5–17(19)mm, ascending to reflexed at anthesis, appressed after anthesis or the lower branches sometimes remaining spreading to reflexed.

(7)10– 20 cm; lowest node 1(2)-branched;

branches 3–16 cm, spreading to drooping.

Spikelets

(5.8)7.5–17(19)mm, with (2)3–7(9) florets.

8–12.5 × 1–5 mm; (2)3–4(5) florets.

Glumes

glabrous or hairy at the tips only;

lower glumes (2.5)3–5(6)mm, 1–3-veined;

upper glumes (3)4–8 mm, 3–4-veined.

glabrous or scabrous on the midvein and minutely scabrous toward the tip;

lower glumes 2–4 mm, 1-veined;

upper glumes 3.5–5(6)mm, 1–3-veined.

Caryopses

4–4.5 mm, glabrous.

4–5 mm;

tips hairy.

Ovaries

apex glabrous.

apex hairy.

Leaf anatomy

cross sections 0.35–0.6 × 0.55– 0.7 mm; more or less round or hexagonal;

veins (4)5(6);

ribs (1)3(5); dorsal sclerenchyma in broad bands more than twice as wide as thick, occasionally continuous.

Lemma(s)

(5.8)6–8(10)mm, 0(1)-veined;

hairs on the distal part only;

lemma awns (1)2–6(7) mm; shorter than to occasionally equaling the lemma body.

6–9 mm; (3)5-veined, scabrous over the entire surface or more so on the veins;

lemma awns 10–15 mm, crinkled, curved; longest awns much longer than the lemma bodies.

Anthers

(2.5)3.2–4(4.5) mm.

2.5–4 mm.

Calluses

(0.3)0.4–0.6 mm; longer than wide; hairy.

2n

=28.

=28.

Festuca idahoensis

Festuca subuliflora

Distribution
[WildflowerSearch map]
[BONAP county map]
[WildflowerSearch map]
[BONAP county map]
Discussion

Prairie, grassland, shrub-steppe, open pine forest, often in partial shade or on north-facing slopes; also on south-facing slopes in subalpine and alpine zones. 100–3000 m. BR, BW, Casc, Col, ECas, Lava, Owy. CA, ID, NV, WA; north to British Columbia, northeast to Saskatchewan, SD, and NM. Native.

Festuca idahoensis is the most common fine-leaved fescue east of the Cascades. However, very similar fescues have been introduced. Festuca trachyphylla and F. valesiaca, planted on roadsides and used to renovate dry pastures, have shorter lemmas and denser inflorescences. Robust individuals of F. occidentalis can be similar to F. idahoensis, but in F. occidentalis many of the lemma awns are longer than the lemmas. In alpine sites, F. idahoensis can be confused with F. brachyphylla and F. saximontana, which have shorter lemmas. Plants west of the crest of the Cascades that were once included in F. idahoensis are now recognized as a distinct species, F. roemeri, which has broader leaves than F. idahoensis.

Mesic to dry forests. 0–1500 m. Casc, CR, Sisk, WV. CA, WA; north to British Columbia. Native.

Festuca subuliflora is a leafy-stemmed forest grass with a nodding inflorescence, similar to F. subulata, which tends to grow in moister microsites. The unusual elongated calluses of F. subuliflora probably aid in dispersal. See F. subulata for a discussion of similar species.

Source Flora of Oregon, volume 1, page 410
Barbara Wilson, Richard Brainerd, Nick Otting
Flora of Oregon, volume 1, page 415
Barbara Wilson, Richard Brainerd, Nick Otting
Sibling taxa
F. brachyphylla, F. californica, F. campestris, F. elmeri, F. filiformis, F. lemanii, F. occidentalis, F. roemeri, F. rubra, F. saximontana, F. subulata, F. subuliflora, F. trachyphylla, F. valesiaca, F. viridula
F. brachyphylla, F. californica, F. campestris, F. elmeri, F. filiformis, F. idahoensis, F. lemanii, F. occidentalis, F. roemeri, F. rubra, F. saximontana, F. subulata, F. trachyphylla, F. valesiaca, F. viridula
Synonyms Festuca idahoensis var. idahoensis, Festuca idahoensis var. oregona
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