Festuca of North America

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

Festuca arizonica Vasey

Nomenclature

ARIZONA FESCUE, PINEGRASS, MOUNTAIN BUNCHGRASS.

Contrib. U.S. Natl. Herb. 1: 277. 1893. F. ovina var. arizonica (Vasey) Hack. ex Beal, Grasses N. Am. 2: 598. 1896. F. altaica subsp. arizonica (Vasey) St.-Yves, Candollea 2: 267. 1925. Type: U.S.A. Arizona: Flagstaff, 1887, S.M. Tracy 118. Holotype US!

F. vaseyana Hack. ex Beal, Grasses N. Am. 2: 601. 1896. Type: U.S.A. Colorado: Veta Pass, 1884, G. Vasey s.n. US! Beal (1896) noted that the plants were mixed with those labelled F. scabrella.

F. scabrella var. asperrima Hack. ex Beal, Grasses N. Am. 2: 605. 1896. Type: U.S.A. Colorado: Veta Pass at an altitude of 9300 feet. 1884. G. Vasey s.n. Holotype US!

F. pinetorum Swallen, Contrib. U.S. Natl. Herb. 29: 397. 1950. Type: Mexico. Nuevo Leon: Municipality Zaragoza, Cerro del Viego, 15 miles west of Dulces Nombres, altitude 3330 m, 18 August 1948, F.G. Meyer & D.J. Rogers 2977. Holotype: US.

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

Vegetative morphology. Sheaths glabrescent (at least near the ligule), 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 (open almost to the base; prophylls 1–3 cm long with trichomes on the veins, occur among the sheaths). Collars glabrous. Auricles represented by distinct, erect, swellings (small, because the leaves are long and narrow). Auricular cilia absent. Ligules 0.5–1.5(–2) mm long, ciliate. Leaf blades 15–25(–40) cm long, erect, stiffish. Adaxial blade surfaces glabrous or with trichomes, abaxial blade surfaces with trichomes. Leaf blades plicate; 0.3–0.41–0.5 mm wide, 0.35–0.55–0.65 mm deep. Veins 5 (consistently). Adaxial to abaxial sclerenchyma strands absent (sclerenchyma strands may occur between the abaxial margin and some veins). Abaxial sclerenchyma well developed, in broad bands or continuous (seven heavy sclerenchyma zones opposite veins and at the leaf margins). Ribs 5 (poorly or well developed). Uppermost culm leaf sheaths not inflated. Flag leaf blades 5–14 cm long. Culm nodes becoming exposed, 3; internodes densely pubescent (at least near the base of the inflorescence).

Floral morphology. Inflorescence (4–)6–12(–20) cm long. Inflorescence branches at the lowest node 1–2, appressed after anthesis or spreading, (2.5–)6–12 cm long. Rachis angular in cross section, trichomes mainly on the ridges. Spikelets loosely scattered in an open panicle with slender branches (spikelets towards the ends of the branches); 4–7 on the longest branches; 6–16 mm long, 3–6 mm wide. Proliferating spikelets absent (not recorded for this taxon). Florets 4–6(–8). Glumes unequal, glabrous (or almost glabrous), margins ciliate. First glume 3–4.8 mm long, veins 1. Second glume shorter than the first lemma, 4.5–6.5(–7) mm long, veins 3. Rachilla internodes antrorsely scabrous. Lemma callus not elongated. Lemma 5.5–8(–9) mm long, nerveless in dorsal view or sometimes with only the centre vein distinct, glabrous (mainly) or with trichomes, trichomes on the upper portion only (and along the main vein); apex entire. Lemma awn 0.4–1.5(–2.7) mm long. Palea 6.2–8 mm long, distinctly pubescent between the keels. Lodicules with marginal teeth, glabrous, 0.8–1.3 mm long. Anthers 3–3.8 mm long. Ovary apex pubescent. Caryopsis 3–3.5 mm long.

Cytology. 2n = 42.

Habitat and Distribution. Native; alpine (abundant in association with pondersoa pine, on slopes, mesas and in open parks where is occurs. It is often associated with mountain muhly, pine dropseed and cinquefoil, but also forms almost pure stands with bunches only a few inches apart.). It frequently occurs on dry, shallow clay loans, but grows well on sandy, gravelly or rocky soils. Southwestern USA: Ariz.; Rocky Mountains USA: Colo.; South Central USA: N. Mex., Tex.

Classification. Subg. Festuca L.

Notes

Cronquist et al. (1977) in Intermountain Flora recognized this taxon but with some reservations because it .."is closely related to F. idahoensis, and some long-awned forms in Arizona may link the two in an integrating fashion that would warrant making F. idahoensis a variety of F. arizonica." In the various analyses reported in Lefkovitch (1993), F. arizonica usually remained separate from F. calligera (Piper) Rydb., F. idahoensis Elmer, and other species that have been linked in the literature to F. ovina. In the results in Aiken et al. (1997), F. arizonica separated at diagnostic level 6 from all other taxa in the database. When the plants are observed in their natural habitats, F. arizonica above 2800 m in Arizona grasslands, and F. altaica Trin. near sea level on the Arctic coast of the Yukon, or in the mountains of British Columbia, these species appear to be very similar bunch grasses with conspicuous persisting leaf sheaths (see illustrations in the image library).

Festuca arizonica is unambiguously a species distinct from F. idahoensis. The three characters, sheaths conspicuous and persisting at the base of the plant, upper culm internodes with dense trichomes, and ovary apex densely hairy, have not previously been included in descriptions of F. arizonica, but have been checked by S.G. Aiken and found to be consistent on all specimens examined. Plants of F. idahoensis differ in having glabrous culm internodes and ovaries.

Aldon and Barstad (1987) in reporting on the Escudilla Mountain Research Natural area, stated that "the Festuca species found in both Middle Meadow and Bead Spring is a giant expression, perhaps not Festuca arizonica at all, but an unnamed species characterized by polyploidy". A voucher specimen justifying this comment was examined by S.G. Aiken (1994) and it is considered to be a large and robust plant of F. arizonica.

This species is not as palatable as many other range species (Dayton 1937) but is important because of its abundance and, on many ranges it furnishes much of the forage. It is eaten by all classes of livestock, but is more readily grazed by cattle and horses, than by sheep. Arizona fescue is not particularly resistant to grazing and even moderately close grazing tends to reduce the cover.

Although Arizona fescue produces an abundance of viable seed, artificial reseeding experiments with it on mountain ranges in the West have not been very successful. Sowings were made in 1913 on the Coconino Plateau in northern Arizona, but although many seedlings resulted and attained average height, most of them subsequently succumbed. The seedlings that did mature produced little seed (Forsling and Dayton, 1931).

Three endophytic fungal symbionts of Endochloe typhina have been reported for F. arizonica (An et al. 1992).

Illustrations

• Plant habit. Left, small photograph showing yellow green plants of F. arizonica (in the distance) growing in the same area as bluish green, shorter plants of F. calligera (foreground), on Gillespie Flat, Apache Co. Arizona. Photograph by Carl-Eric Granfelt, 21 July 1994. Centre, close up of F. arizonica. Right, close up of F. calligera. • Leaf anatomy. Leaf cross section of F. arizonica. Plicate leaf blades 0.3–0.41–0.5 mm wide, 0.35–0.55–0.65 mm deep, with 5 veins, consistently. Adaxial to abaxial sclerenchyma strands are absent and sclerenchyma strands may occur between the abaxial margin and some veins. Abaxial sclerenchyma strands are well developed, in broad bands or continuous as 7 heavy sclerenchyma zones opposite the veins and at the leaf margins. There are 5 ribs, that are poorly or well developed. • F. arizonica dominated grassland habitat. Carl-Eric Granfelt examining previous season's growth of F. arizonica in N.E. Arizona, White Mountains, in Apache-Sitgreaves National Forest, at altitude 2803 m, May 1993. • F. arizonica growing with Ponderosa pine. Left, F. arizonica growing with Ponderosa pine, at approximately 2800 m on San Francisco Mountains, Arizona, May 1993. Right, close up of plants at the end of the winter. • Type specimen of name in synonymy: US. Type specimen of F. vaseyana Hack. ex Beal Grasses N. Amer. 2: 601. 1896. Label reads, "F. ovina var. arizonica Hack. Dr. Geo. Vasey 1884." Type: U.S.A. Colorado: 1884, Veta Pass, G. Vasey s.n. 1884. US 556147. • Herbarium specimen of interest: NY. Specimen collected in Arizona by H.H. Rusby in 1883. The picture is from a photograph of the herbarium specimen. In the left hand corner is the label F. arizonica V. The collection was made in the same year as H.H. Rusby collected the type specimen of F. calligera as F. amethystina var. asperrina that is illustrated with F. calligera. The two samples contrast in the base of the plant and the length of the leaves. • 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).

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