Festuca of North America


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

Festuca occidentalis Hook.



Fl. Bor. Am. 2: 249. 1840. Type: U.S.A. Oregon: on the plains of the Columbia, near the sea, 1825, Douglas 224. Isotype: GH! Lectotype: K. (Alexeev 1985).

F. ovina var. polyphylla Vasey in Beal, Grasses N. Am. 2: 597. 1896. Type: U.S.A. Oregon: T.H. Howell 26, and Henderson 8.

F. rubra var. longiseta (Hack.) sensu Beal. Grasses N. Am. 2: 606. 1896, but not as to basionym. F. longiseta Hegetschw. & Heer, Fl. Schw. 92: 1840. Type: Canada. British Columbia: Vancouver Island, 1887, Macoun.

Habit. Plants deep green, (25–)45–110 cm high, densely tufted, tiller bases stiffly erect or not stiffly erect, bases purplish or not purplish, horizontal rooting stems absent. Vegetative shoots arising from within existing sheaths.

Vegetative morphology. Sheaths glabrous or with trichomes (that are minute hairs; silica deposits sometimes prominent), not conspicuous at the base of the plant, remaining entire, not conspicuously splitting between the veins (in the first year), open more than half their length. Collars glabrous. Auricles represented by distinct, erect, swellings. Auricular cilia absent. Ligules 0.1–0.4(–0.5) mm long, ciliate. Leaf blades (5–)10–20(–40) cm long, more or less lax. Adaxial blade surfaces with trichomes, abaxial blade surfaces glabrous (rarely scaberulous). Leaf blades plicate (becoming longitudinally sulcate when dry); 0.25–0.35–0.6 mm wide, 0.35–0.64–0.75 mm deep. Veins (3–)5–7. Adaxial to abaxial sclerenchyma strands absent. Abaxial sclerenchyma poorly developed, in discrete, relatively narrow strands opposite the veins. Ribs 1 (well defined, 2–4 poorly defined). Uppermost culm leaf sheaths not inflated (usually, somewhat inflated when inflorescence is in the boot). Flag leaf blades 3–12 cm long. Culm nodes becoming exposed, 2; internodes glabrous.

Floral morphology. Inflorescence 5–20 cm long. Inflorescence branches at the lowest node 1–2, appressed after anthesis or spreading, (1–)2–10 cm long. Rachis angular in cross section, trichomes mainly on the ridges or trichomes over the entire surface. Spikelets loosely scattered in an open panicle with slender branches; 3–6 on the longest branches; 6–12 mm long, 1–3 mm wide. Proliferating spikelets absent (not recorded for this taxon). Florets 2–5(–7). Glumes unequal, with trichomes, vestiture at the apex only, margins ciliate. First glume 2–5 mm long, veins 1. Second glume shorter than the first lemma, 3–6 mm long, veins (1–)3. Rachilla internodes antrorsely scabrous. Lemma callus not elongated. Lemma 4–7(–8) mm long, nerveless in dorsal view or sometimes with only the centre vein distinct, with trichomes (sparsely scaberulous), trichomes on the upper portion only (usually) or over the entire surface; apex entire. Lemma awn 3–12 mm long. Palea 4–7 mm long, distinctly pubescent between the keels. Lodicules with marginal teeth, glabrous or ciliate (rarely), 0.7–1.5 mm long. Anthers (1–)1.7–3 mm long. Ovary apex pubescent. Caryopsis 3–4.5 mm long.

Cytology. 2n = 14, 28, 42, 46, 56, 64, 70.

Habitat and Distribution. Native. Canada: Ont., Alta., B.C.; Northwestern USA: Oreg., Wash.; Southwestern USA: Calif.; Rocky Mountains USA: Idaho, Mont., Wyo.; North Central USA: S. Dak., Wis.; Northeastern USA: Mich.

Classification. Subg. Festuca L.


In the above description, data for Canadian specimens (Aiken and Darbyshire 1990) are combined with data gathered from Californian specimens (Aiken 1993) and encompass the size ranges found in this species throughout North America.

Hitchcock et al. (1969) commented that, "although sometimes approaching F. idahoensis this species is nearly always recognizable from the former by the smaller lemmas, some of which are always exceeded by the awn". The fine leaves of F. occidentalis are angular in outline from fine bundles of underlying sclerenchyma, those of F. idahoensis Elmer s.l. are more rounded in outline from wide bands of underlying sclerenchyma (Aiken and Consaul 1995). The ovary apices of plants of F. occidentalis are densely hairy, those of plants of F. idahoensis are glabrous.


• Line drawing. Illustrated in Piper (1906) as F. occidentalis. • Leaf anatomy. Leaf cross section of F. occidentalis. Leaf blades are 0.25–0.35–0.6 mm wide and 0.35–0.64–0.75 mm deep, with (3-)5–7 veins. Adaxial to abaxial sclerenchyma strands are absent. Abaxial sclerenchyma strands are poorly developed, in discrete, relatively narrow strands opposite the veins. There is one well defined rib and 2–4 poorly defined ribs. • Isotype specimen: GH. Isotype specimen of F. occidentalis. Main label reads, "F. occidentalis Hook. Plains of the Columbia, Douglas. Herb. Tor." GH. • Isotype specimen: NY. Isotype of F. occidentalis Hook. Plains of the Columbia, Douglas. Herb. Tor. NY. On the original label there is a dark number of 224, which is the number of the holotype, but beside that number is a fainter, more likely original number of 228. • 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).