Festuca of North America


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

Festuca idahoensis subsp. roemeri (Pavlick) S. Aiken


F. idahoensis subsp. roemeri (Pavlick) S. Aiken, Can. J. Bot. (Aiken et al. 1997). F. idahoensis var. roemeri Pavlick, Can. J. Bot. 61: 350. 1983. F. roemeri (Pavlick) E. B. Alexeev, Novosti Sist. Vyssh. Rast. 22: 23. 1985. Type: Canada. British Columbia: Vancouver Island, Mt. Finlayson, 28 June 1978, L. E. Pavlick 78–233. Holotype: V!

F. amethystina var. asperrima subvar. robusta St.-Yves, Candollea 2: 264. 1925, pro parte, typo excl.

Habit. Plants bluish gray green (moderately shiny or glaucous), 35–100 cm high, densely tufted, tiller bases stiffly erect, bases purplish or not purplish, horizontal rooting stems absent. Vegetative shoots arising from within existing sheaths.

Vegetative morphology. Sheaths glabrous (usually) or glabrescent or with trichomes (herbarium voucher, V 98918), conspicuous at the base of the plant, persisting for more than 1 year, remaining entire, not conspicuously splitting between the veins, open more than half their length (prophylls 1.5–3 cm long, delicate, with glabrescent trichomes on the veins). Collars glabrous. Auricles represented by distinct, erect, swellings. Auricular cilia absent. Ligules 0.1–0.4 mm long, ciliate. Leaf blades 15–35 cm long, erect, stiffish. Adaxial blade surfaces glabrous (usually) or with trichomes (to 4 mm long), abaxial blade surfaces glabrous. Leaf blades plicate, drying to 1.2 mm when pressed; 0.4–0.54–0.8 mm wide, 0.75–0.9–1.2 mm deep. Veins (5–)7(–10). Adaxial to abaxial sclerenchyma strands absent. Abaxial sclerenchyma well developed, in broad bands or continuous (the broad bands particularly well developed at the midvein and leaf margins, and often only in these positions). Ribs 5–9. Uppermost culm leaf sheaths not inflated. Flag leaf blades 7–12(–18) cm long. Culm nodes becoming exposed, 1; internodes glabrous.

Floral morphology. Inflorescence (8–)10–20(–25) cm long. Inflorescence branches at the lowest node 1–2, appressed after anthesis, 3–7 cm long. Rachis angular in cross section, trichomes mainly on the ridges. Spikelets aggregated towards the ends of the branches; 4–9(–11) on the longest branches; 9.5–12(–13.5) mm long, 3–5.5 mm wide. Proliferating spikelets absent (not recorded for this taxon). Florets 3–6. Glumes unequal, glabrous or with trichomes, vestiture at the apex only, margins ciliate (minutely). First glume 2–5 mm long, veins 1. Second glume shorter than the first lemma, 4–5.5(–6.2) mm long, veins 3. Rachilla internodes antrorsely scabrous. Lemma callus not elongated. Lemma 6.5–8.2 mm long, nerveless in dorsal view or sometimes with only the centre vein distinct, with trichomes (scaberulous), trichomes on the upper portion only; apex entire. Lemma awn 2–4(–5) mm long. Palea 6.5–8 mm long, distinctly pubescent between the keels. Lodicules with marginal teeth, glabrous, 0.6–1.2 mm long. Anthers 3–4 mm long. Ovary apex glabrous.

Habitat and Distribution. Rangeland, prairie, dry habitats. Canada: B.C.; Northwestern USA: Oreg., Wash.; Southwestern USA: Calif.

Classification. Subg. Festuca L.


First described as a variety, but treated here as a subspecies based on analyses of this database, and unpublished evidence from the seed protein banding profile. It appears to be a geographically distinct taxon. (B.L. Wilson, University of Oregon, personal communication 1996).

Pavlick (1983b) stated that "the habitat of var. roemeri on Vancouver Island is influenced by being in the rain shadow of the Olympic and Vancouver Island mountains and in having mild winters in which most precipitation is rain. ...On Vancouver Island var. roemeri occurs on south-facing, grass balds up to about 500 m elevation and at lower elevations in open, often rocky outcrop areas in the Pseudotsuga menziesii or Quercus garryana forests."

Pavlick (1983b) gave the following attributes for distinguishing the taxa:

Basal sheaths 0.8–1.2 mm diameter about 7 mm below summit; panicle 7–11 cm long; basal leaf diameter (long axis) (0.3–)0.5–0.7 mm diameter, plant thus fine in aspect; leaves plicate, hexagonal, involute (near midleaf), usually with 5 nerves, the ribs (adaxial side) densely long pubescent; range in Canada, east of the Cascade Mountains... subsp. idahoensis

Basal sheaths 1.0–1.4 mm diameter about 7 mm below summit; panicle 9.5–16.0 cm long; basal leaf diameter (long axis)(0.5–)0.6–0.9(–1.2) mm, plant thus coarse in aspect; leaves obovate-pyriform in cross section (near midleaf) with margins tending to open, usually with 7 nerves, the ribs (adaxial side) lightly scabrous to sparsely short pubescent; range in Canada, west of the Cascade Mountains (southeastern Vancouver Island and Gulf Islands)...subsp. roemeri


• Habit and close up. Habitat and close up of F. idahoensis subsp. roemeri. Left, plants growing on the steep slope of Cape Pepetua, Oregon, March 1996. Deep green plants growing, immediately below where the person is sitting, are Chewings fescue. The remainder of the hill side is dominated by F. idahoensis subsp. roemeri. Right, close up of up of F. idahoensis subsp. roemeri in early spring. • Leaf anatomy. Leaf cross section of F. idahoensis subsp. roemeri. Leaf blades are 0.4–0.54–0.8 mm wide and 0.75–0.9–1.2 mm deep, with (5-)7(-10) veins. Adaxial to abaxial sclerenchyma strands are absent. Abaxial sclerenchyma are well developed, in broad bands or continuous. The broad bands are particularly well developed at the midvein and leaf margins, and often only in these positions. There are 5–9 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).