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Thurber fescue, Thurber's fescue

blue bunchgrass, blue fescue, bluebunch fescue, Idaho fescue

Habit Plants densely cespitose, without rhizomes. Plants densely cespitose, without rhizomes.
Culms

(45) 60-100(120) cm, glabrous, smooth or scabrous below the inflorescence.

25-85 (100) cm, usually smooth, glabrous, occasionally scabrous below the inflorescences.

Sheaths

closed for less than 1/3 their length, smooth or scabrous, persistent;

collars glabrous;

ligules 2-5(9) mm, entire or lacerate, not ciliate;

blades 1.5-3 mm wide, 0.8-1.8 mm in diameter when conduplicate, deciduous, abaxial surfaces scabrous, adaxial surfaces scabrous or pubescent, veins 9-15, ribs 7-13;

abaxial sclerenchyma a more or less continuous band;

adaxial sclerenchyma present;

girders usually formed at the major veins, sometimes only pillars present.

closed for less than 1/2 their length, smooth or scabrous, rarely pilose, persistent;

collars glabrous;

ligules 0.2-0.6 mm;

blades (0.3)0.5-0.9(1.5) mm in diameter, conduplicate, abaxial surfaces smooth or scabrous, adaxial surfaces scabrous or pubescent, rarely pilose, often glaucous or bluish, veins (3)5(7), ribs (1)3-5, well defined;

abaxial sclerenchyma in 5-7 wide, irregular strands;

adaxial sclerenchyma absent.

Inflorescences

(7)10-15(17) cm, open, with 1-2(3) branches per node;

branches 4.5-9 cm, lax, erect or spreading, spikelets borne towards the ends of the branches.

(5)7-15(20) cm, loosely contracted or open, with 1-2 branches per node;

branches usually somewhat spreading at maturity, sometimes erect, rarely reflexed, lower branches with 2+ spikelets.

Spikelets

(8)10-14 mm, with (3)4-5(6) florets.

(5.8) 7.5-13.5(19) mm, with (2)4-7(9) florets.

Glumes

unequal to subequal, ovate-lanceolate, scabrous or smooth, acute;

lower glumes (2)3.5-5.5 mm;

upper glumes (2.5)4.5-6.5(7) mm;

lemmas 6-10 mm, lanceolate to ovate-lanceolate, scabrous or smooth, unawned, sometimes mucronate, mucros to 0.2 mm;

paleas shorter than to as long as the lemmas, intercostal region puberulent distally;

anthers 3-4.5 mm;

ovary apices densely pubescent.

exceeded by the upper florets, ovate-lanceolate to lanceolate, mostly smooth, sometimes scabrous distally;

lower glumes 2.4-5(6) mm;

upper glumes 3-6(8) mm;

lemmas 5-8.5(10) mm, scabrous at the apices, awns (1.5)3-6(7) mm, usually more than 1/2 as long as the lemma bodies;

paleas shorter than to about as long as the lemmas, intercostal region scabrous or puberulent distally;

anthers 2.4-4.5 mm;

ovary apices glabrous.

2n

= 28, 42.

= 28.

Festuca thurberi

Festuca idahoensis

Distribution
from FNA
AZ; CO; NM; SC; UT; WY
[WildflowerSearch map]
[BONAP county map]
from FNA
AZ; CA; CO; ID; MT; NM; NV; OR; SD; UT; WA; WY; AB; BC; SK
[WildflowerSearch map]
[BONAP county map]
Discussion

Festuca thurberi is a large bunchgrass of dry, rocky slopes and hills, open forests, and meadows in montane and subalpine regions, at (1000)2000-3500 m. Its range extends from southern Wyoming south through Utah and Colorado to New Mexico.

(Discussion copyrighted by Flora of North America; reprinted with permission.)

Festuca idahoensis grows in grasslands, open forests, and sagebrush meadow communities, mostly east of the Cascade Mountains, from southern British Columbia eastward to southwestern Saskatchewan and southward to central California and New Mexico. It extends up to 3000 m in the southern part of its range. It is often a dominant plant, and provides good forage. The young foliage is particularly palatable.

Festuca idahoensis differs from F. arizonica (see previous), with which it is sometimes confused, in its less prominently ribbed blades and glabrous ovary apices. It has frequently been included in F. ovina (p. 422).

(Discussion copyrighted by Flora of North America; reprinted with permission.)

Source FNA vol. 24, p. 408. FNA vol. 24, p. 438.
Parent taxa Poaceae > subfam. Pooideae > tribe Poeae > Festuca > subg. Festuca > sect. Breviaristatae Poaceae > subfam. Pooideae > tribe Poeae > Festuca > subg. Festuca > sect. Festuca
Sibling taxa
F. altaica, F. amethystina, F. arizonica, F. auriculata, F. baffinensis, F. brachyphylla, F. brevissima, F. californica, F. calligera, F. campestris, F. dasyclada, F. earlei, F. edlundiae, F. elmeri, F. filiformis, F. frederikseniae, F. glauca, F. groenlandica, F. hallii, F. heterophylla, F. hyperborea, F. idahoensis, F. lenensis, F. ligulata, F. minutiflora, F. occidentalis, F. ovina, F. paradoxa, F. prolifera, F. pseudovivipara, F. roemeri, F. rubra, F. saximontana, F. sororia, F. subulata, F. subuliflora, F. subverticillata, F. trachyphylla, F. valesiaca, F. versuta, F. viridula, F. viviparoidea, F. washingtonica
F. altaica, F. amethystina, F. arizonica, F. auriculata, F. baffinensis, F. brachyphylla, F. brevissima, F. californica, F. calligera, F. campestris, F. dasyclada, F. earlei, F. edlundiae, F. elmeri, F. filiformis, F. frederikseniae, F. glauca, F. groenlandica, F. hallii, F. heterophylla, F. hyperborea, F. lenensis, F. ligulata, F. minutiflora, F. occidentalis, F. ovina, F. paradoxa, F. prolifera, F. pseudovivipara, F. roemeri, F. rubra, F. saximontana, F. sororia, F. subulata, F. subuliflora, F. subverticillata, F. thurberi, F. trachyphylla, F. valesiaca, F. versuta, F. viridula, F. viviparoidea, F. washingtonica
Synonyms F. idahoensis var. oregona
Name authority Vasey Elmer
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