Festuca of North America


S. G. Aiken, M. J. Dallwitz, C. L. McJannet, and L. L. Consaul

Festuca viridula Vasey



U.S. Dept. Agric. Div. Bot. Bull. 132: pl. 93. 1893. Gnomonia viridula (Vasey) Lunell, Am. Midl. Natl. 4: 224. 1915. F. viridula var. vaseyana St.-Yves, Candollea 2: 265. 1925. Type: U.S.A. Washington: Mt. Paddo, (=Mt. Adams), 3–6000 feet, 6 July 1882, W.N. Suksdorf s.n. Lectotype: US! (Pavlick, 1983c, discusses why this specimen and not a collection from California by Bolander is the lectotype).

F. gracillima Thurb. in S. Watson, Bot. Calif. 2: 318. 1880, non Hook. f., Fl. Antarctic. 383. 1847.

Habit. Plants deep green, (35–)50–100 cm high, densely tufted (forming small clumps), tiller bases stiffly erect, bases purplish or not purplish, horizontal rooting stems absent. Vegetative shoots arising from within existing sheaths.

Vegetative morphology. Sheaths glabrous, not conspicuous at the base of the plant (as they tend to turn brown early), remaining entire, not conspicuously splitting between the veins, open more than half their length. Collars glabrous. Auricles represented by distinct, erect, swellings. Auricular cilia absent. Ligules 0.2–0.5 mm long, ciliate. Leaf blades 10–25 cm long, erect, stiffish or more or less lax. Adaxial blade surfaces with trichomes (finely puberulent-scaberulous), abaxial blade surfaces glabrous. Leaf blades flat or plicate (loosely rolled), 0.8–2(–2.5) mm wide; 0.4–0.65–1 mm wide, 0.85–1–1.3 mm deep. Veins 7–12. Adaxial to abaxial sclerenchyma strands absent (sclerenchyma sometimes on the top of the ribs). Abaxial sclerenchyma well developed, in broad bands or continuous. Ribs 5–10. Uppermost culm leaf sheaths not inflated. Flag leaf blades 4–8(–12) cm long. Culm nodes becoming exposed, 1–3; internodes glabrous.

Floral morphology. Inflorescence 4–12(–15) cm long. Inflorescence branches at the lowest node 2 (pulvinate at the base), appressed after anthesis, 1.5–3 cm long. Rachis rounded in cross section or angular in cross section, trichomes over the entire surface. Spikelets aggregated towards the ends of the branches; (1–)2–4 on the longest branches; 9–12(–15) mm long, 2–2.5 mm wide. Proliferating spikelets absent (not recorded for this taxon). Florets (2–)3–6(–7). Glumes unequal, with trichomes, vestiture at the apex only, margins ciliate. First glume (2.4–)3.5–5 mm long, veins 1. Second glume shorter than the first lemma, 4.5–6(–7.5) mm long, veins 3. Rachilla internodes 1–1.5 mm long, antrorsely scabrous (minutely scaberulous; the rachilla is usually visible, but not conspicuously zig-zag as it often is in spikelets of F. idahoensis). Lemma callus not elongated. Lemma (5.5–)6.5–8 mm long, nerveless in dorsal view or sometimes with only the centre vein distinct, glabrous or with trichomes (scaberulous), trichomes on the upper portion only (and along margins, scaberulous); apex entire. Lemma awn present or absent. Lemma awn 0–0.5(–1.4) mm long. Palea (5–)6–7(–8.2) mm long, distinctly pubescent between the keels (usually). Lodicules with marginal teeth, glabrous or ciliate, 1.2–1.5 mm long. Anthers (2–)3–4(–5) mm long. Ovary apex pubescent. Caryopsis 3.5–5 mm long.

Cytology. 2n = 28.

Habitat and Distribution. Native; rangeland, prairie, dry habitats. Subalpine or alpine slopes and rock slides, and meadows to well above timberline. Canada: Alta. (recorded from this province but no voucher for the record has been found), B.C.; Northwestern USA: Oreg., Wash.; Southwestern USA: Calif., Nev.; Rocky Mountains USA: Idaho, Mont.

Classification. Subg. Festuca L.


Pavlick (1983c) documented confusion over the lectotype of this species and explained that Vasey's (1893a) selection was correct. He documented that Piper (1906) misinterpreted the protologue in Vasey (1893b) and selected a specimen collected by Bolander in California as the type; he was followed by Hitchcock and Chase (1951).

A taxon that has been placed into synonymy with F. viridula is F. howellii Hack. ex Beal, (Grasses N. Am. 2: 591. 1896. F. viridula var. howellii St.-Yves, Candollea 2: 266. 1925. Type: U.S.A. Oregon: Josephine Co., Deer Creek Mountains, July 1887, Thomas Howell. US!) Whether this type is a specimen of F. viridula is the subject of a study by B.L. Wilson (personal communication, 1995).

F. viridula was described as intermediate to F. idahoensis var. oregona Hack. ex Beal (Hitchcock et al. 1969). These authors commented that F. viridula "approaches F. idahoensis, especially the var. oregona but differs not only because of the unawned or only awn-tipped lemmas, but also because of the flat blades and the marcescent fibrous veins of the sheaths, in this respect resembling F. rubra". It differs from both these species in having ovaries with dense pubescence at the apex. The sheaths of F. viridula s.s. remain entire; those of F. washingtonica are marcescent (see notes under the latter species).

Where it occurs, particularly in the United States, this species is an important alpine and subalpine forage that is highly palatable and nutritious.


• Line drawing. Illustration of F. viridula by R. Cowing that accompanied the original description of this species Vasey (1892). • Leaf anatomy. Leaf cross section of F. viridula. Leaf blades are 0.4–0.65–1 mm wide and 0.85–1–1.3 mm deep, with veins 7–12. Adaxial to abaxial sclerenchyma strands are absent; sclerenchyma sometimes on the top of the ribs. Abaxial sclerenchyma are well developed, in broad bands or continuous. There are 5–10 ribs. • Distribution map

The interactive key provides access to the character list, illustrations, full and partial descriptions, diagnostic descriptions, differences and similarities between taxa, lists of taxa exhibiting specified attributes, and summaries of attributes within groups of taxa.

Cite this publication as: ‘Aiken, S.G., Dallwitz, M.J., McJannet, C.L. and Consaul, L.L. 1996 onwards. Festuca of North America: descriptions, illustrations, identification, and information retrieval. Version: 19th October 2005. http://delta-intkey.com’. Aiken, Dallwitz, McJannet, and Consaul (1997) should also be cited (see References).