Festuca of North America


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

Festuca rubra approaching ‘aucta’ Krecz. and Bobr.


In Komarov, Fl. U.R.S.S. 2: 518, 767. 1934. Type: U.S.A. Alaska: Ins. Bering, 25 August 1894, N. Grebnitzky" (Chase and Niles 1962).

Habit. Plants yellowish green or deep green (inflorescences often purplish, drying brown), 30–85 cm high, not densely tufted, tiller bases not stiffly erect (loosely curving from rhizomes), bases purplish (or reddish brown), horizontal rooting stems present. Vegetative shoots arising outside, or breaking through the base of existing sheaths.

Vegetative morphology. Sheaths glabrous or with trichomes, not conspicuous at the base of the plant, splitting between the veins, closed more than half their length. Collars glabrous. Auricles represented by distinct, erect, swellings. Ligules 0.2–0.3 mm long, ciliate. Leaf blades 10–35 cm long, more or less lax. Adaxial blade surfaces with trichomes, abaxial blade surfaces glabrous. Leaf blades flat or plicate (usually), 2–3 mm wide (when applicable); 0.4–1(–1.4) mm wide, 0.8–1.3 mm deep. Veins 5–9. Adaxial to abaxial sclerenchyma strands absent (sclerenchyma occasionally present on the tops of the ribs). Abaxial sclerenchyma poorly developed, in discrete, relatively narrow strands opposite the veins. Ribs prominently developed. Uppermost culm leaf sheaths not inflated. Flag leaf blades 2–8 cm long. Culm nodes becoming exposed (usually), 1 (when visible); internodes glabrous, or scabrous-hirsute (near the inflorescence).

Floral morphology. Inflorescence paniculate, 3.5–10 cm long. Inflorescence branches at the lowest node 1 or 2, appressed after anthesis, 1.5–5 cm long. Rachis angular in cross section, trichomes mainly on the ridges. Spikelets aggregated towards the ends of the branches; 2–5 on the longest branches; 7–14 mm long, 3–4 mm wide. Proliferating spikelets absent. Florets 5–8(–9). Glumes unequal, with trichomes, vestiture at the apex only (sparse), margins ciliate. First glume 3–3.2 mm long, veins 1. Second glume shorter than the first lemma, 3.5–4.5 mm long, veins 3. Rachilla internodes 1–1.5 mm long, antrorsely scabrous. Lemma callus not elongated. Lemma 5.5–7 mm long, nerveless in dorsal view or sometimes with only the centre vein distinct, with trichomes, trichomes over the entire surface (varying from sparse to relatively dense); apex entire. Lemma awn 1–2 mm long. Palea 5.3–6.5 mm long, distinctly pubescent between the keels. Lodicules with marginal teeth, glabrous, 0.7–1 mm long. Anthers 2.8–4 mm long. Ovary apex glabrous. Caryopsis 3–4 mm long.

Habitat and Distribution. Arctic, or alpine. Growing in and around spruce bogs, and open spruce woods, in the partial shade of black poplar. Recorded from river valleys and sandy volcanic soil. This taxon is considered rare in sand dunes, but common in adjacent woods. Canada: Yukon; Northwestern USA: Alaska.

Classification. Subg. Festuca L.


Tzvelev (1976) treated the name 'aucta' as synonymous with F. rubra subsp. rubra. Within F. rubra there are robust specimens collected inland in Alaska and the Yukon that are distinct from saline tolerating F. rubra plants collected near the seashore, particularly as the former usually have conspicuous awns and the latter are almost awnless. Data for the above description were gathered from surprisingly large plants of F. rubra s.l. that had been collected in Alaska and the Yukon. Collections at CAN from the area range in size from plants similar to those from southern distibutions of F. rubra to plants with conspicuously larger and more robust inflorescences, but many intermediates occur.

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).