Festuca of North America

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

Festuca brachyphylla subsp. coloradensis Frederiksen s.s.

Nomenclature

Nord. J. Bot. 2: 529. 1982. Type: U.S.A. Colorado: Summit Co., Hoosier Ridge, 18 August 1960, K.A. Holmen, A.E. Porsild, and W.A. Weber fix 850. Holotype: C.

F. brachyphylla Schult. & Schult. f. s.l. Mantissa 2: 646. 1827. Data were gathered 1987–1990 and reassessed, 1994–1995.

Habit. Plants yellowish green or bluish gray green (often yellowish from accumulated straw), 2.5–12 cm high (culms less than twice the length of the basal leaves, Frederiksen 1977), densely tufted, tiller bases stiffly erect, bases purplish (slightly) 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, remaining entire, not conspicuously splitting between the veins, closed more than half their length (Frederiksen 1982, character in the key; prophylls that have trichomes on the veins, occur among the sheaths and are sometimes obvious at the base of the plant). Collars glabrous. Auricles represented by distinct, erect, swellings. Auricular cilia absent. Ligules 0.1–0.5 mm long, ciliate. Leaf blades 2–6 cm long, erect, stiffish. Adaxial blade surfaces with trichomes (sometimes almost glabrous), abaxial blade surfaces glabrous. Leaf blades plicate; (0.25–)0.3–0.42–0.5 mm wide, 0.5–0.64–0.95 mm deep. Veins 3–5. Adaxial to abaxial sclerenchyma strands absent. Abaxial sclerenchyma poorly developed, in discrete, relatively narrow strands opposite the veins (but sometimes more strongly developed than in arctic specimens of subsp. brachyphylla). Ribs 1 (well defined, 2–4 variously defined lateral ribs). Uppermost culm leaf sheaths not inflated. Flag leaf blades 0.8–2.5 cm long. Culm nodes never exposed; internodes glabrous.

Floral morphology. Inflorescence 1.5–2.5 cm long. Inflorescence branches at the lowest node 1–2, appressed after anthesis, 0.4–0.8 cm long. Rachis angular in cross section, trichomes mainly on the ridges. Spikelets aggregated towards the ends of the branches; 1–2 on the longest branches; (3.5–)4–5(–5.5) mm long, 1–2.5 mm wide. Proliferating spikelets absent (not recorded for this taxon). Florets 2–4. Glumes unequal, with trichomes (scaberulous), vestiture over most of the outer surface (and on the midvein), margins ciliate. First glume 1.8–3 mm long, veins 1. Second glume shorter than the first lemma, 2.3–3.6(–4.3) mm long, veins 3. Rachilla internodes 0.6–0.7 mm long, antrorsely scabrous (scaberulous). Lemma callus not elongated. Lemma 3.5–4.5 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 0.7–2(–3.6) mm long. Palea 3–3.5(–4) mm long, distinctly pubescent between the keels. Lodicules with marginal teeth, glabrous, 0.7–0.9 mm long. Anthers 0.9–1.4 mm long. Ovary apex glabrous. Caryopsis 1.8–2.5 mm long.

Cytology. 2n = 28 (There are three vouchers at DAO with 2n=28 for this taxon, collected and determined by T. Mosquin).

Habitat and Distribution. Native; alpine. Southwestern USA: Calif.; Rocky Mountains USA: Colo., Mont., Utah, Wyo. (We have not established whether the two subspecies occur at different altitudes but in the same geographical areas of Idaho, Montana, or Wyoming).

Classification. Subg. Festuca L.

Notes

Frederiksen (1982) photographed relatively large plants of this taxon that she called subsp. coloradensis and relatively small plants that she called subsp. breviculmis. Limited examination of high alpine collections from Arizona, California, Colorado, New Mexico, and Oregon indicates that the taxon occurs at altitudes above 2800 m. Plants of this taxon were observed growing beside F. saximontana subsp. purpusiana (St.-Yves) Tzvelev in the White Mountains of California and in that location the latter plants were conspicuously "more robust", had flowered and were beginning to set seed, while plants of F. brachyphylla subsp. coloradensis were just coming into flower (illustrated in the image library).

Frederiksen (1982) distinguished this subspecies partly because of the recorded chromosome number 2n=28, which differs from that of F. brachyphylla Schult. & Schult. f. subsp. brachyphylla 2n=42. She also distinguished F. brachyphylla subsp. breviculmis Frederiksen as a Californian endemic with a high altitudinal distribution range in the isolation of Californian mountain peaks. Plants collected in Colorado: Summit Lake, 3917 m, 10 July 1988, S. J. Darbyshire 3850, CAN 535149, illustrated in the image library; La Plata County, San Juan National Forest, 37°38'N, 107°37'W, on rock ledges below the summit of Eoleus, 13,900 feet, 29 July 1962, Joan Michener 887, COLO. match collections from the White Mountains of California. Most collections from the Rocky Mountains are larger and occur in a wider range of habitats. Festuca brachyphylla subsp. coloradensis appears to be almost as phenotypically plastic as subsp. brachyphylla.

Illustrations

• Habitat and close up of plant. Left, White Mountains of California at 3800 m, where plants were found growing 100–200 m below the summit (white arrow). F. brachyphylla subsp. coloradensis (upper right) and F. saximontana subsp. purpusiana (lower right) grow within meters of each other at this location. • Plant growing in California. Plant of F. brachyphylla subsp. coloradensis growing in the White Mountains of California. • = F. brachyphylla subsp. coloradensis leaf anatomy. Leaf cross section of F. brachyphylla subsp. breviculmis based on the average of 10 samples from outside of California. Leaf blades are 0.25–0.5 mm wide and 0.5–0.95 mm deep, with 3–5 veins. Adaxial to abaxial sclerenchyma strands are absent. Abaxial sclerenchyma are poorly developed, in discrete, relatively narrow strands opposite the 1 well defined rib and 2–4 variously defined lateral ribs.


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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