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

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, & Weber fix 850 (material fixed for chromosome counts). Holotype: C.

F. brachyphylla Schult. & Schult. f., Mantissa 2: 646. 1827. pro parte, typo excl.

F. brachyphylla subsp. breviculmis Frederiksen, Nord. J. Bot. 2: 530. 1982. Type: U.S.A. California: Inyo Co., Mono Mesa, 24 July 1946, J. Th. Howell 22706. Holotype: CAS.

Habit. Plants yellowish green or bluish gray green (often yellowish from accumulated straw), 2.5–12 cm high (culm usually less than twice the length of the basal leaves), 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 or conspicuous at the base of the plant, persisting for more than 1 year, remaining entire, not conspicuously splitting between the veins, closed more than half their length (Frederiksen, 1982. Among the sheaths are prophylls that have trichomes on the veins. These are sometimes easily observed at the base of the plants). Collars glabrous. Auricles represented by distinct, erect, swellings. Auricular cilia absent. Ligules 0.1–0.5 mm long, ciliate. Leaf blades 1.7–6 cm long, erect, stiffish or more or less lax. Adaxial blade surfaces with trichomes (sometimes almost glabrous), abaxial blade surfaces glabrous. Leaf blades plicate; (0.25–)0.3–0.59(–0.8) mm wide, 0.35–0.95 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 (or very slightly inflated). Flag leaf blades 0.8–2.5 cm long. Culm nodes never exposed; internodes glabrous.

Floral morphology. Inflorescence (0.8–)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, 0.5–2.5 mm wide. Proliferating spikelets absent (not recorded for this taxon). Florets 2–4. Glumes unequal, glabrous or with trichomes (scaberulous), vestiture at the apex only (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 3.3–4.5 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 (the 3.6 mm recorded from a DAO specimen). Palea 3–3.5(–4) mm long, distinctly pubescent between the keels. Lodicules with marginal teeth, glabrous, 0.7–0.9 mm long. Anthers (0.4–)0.9–1.4 mm long. Ovary apex glabrous. Caryopsis 1.8–2.5 mm long.

Cytology. 2n = 28 (T. Mosquin produced 3 counts of 2n=28 from root tip squashes of plants collected in Colorado. The vouchers are at DAO. Frederiksen (1982) found that guard cell measurements of the taxon she recognized as F. brachyphylla subsp. breviculmis suggested that the chromosome number is 2n=28).

Habitat and Distribution. Native; alpine. Southwestern USA: Ariz., Calif. (usually occurring above 2800 m in California on alpine sites in the Sierra Nevada and White Mountains); Rocky Mountains USA: Colo., Mont., Utah, Wyo. (We have not established whether there is a complete geographical separation of the two subspecies, (subsp. brachyphylla and subsp. coloradensis), or whether they occur at different altitudes in the same geographical location in Idaho, Montana, or Wyoming).

Classification. Subg. Festuca L.

Notes

Frederiksen (1982) distinguished this subspecies partly because of the recorded chromosome number 2n=28 which differs from that of F. brachyphylla subsp. brachyphylla 2n=42. She also distinguished F. brachyphylla subsp. breviculmis as a Californian endemic with a high altitude distribution range in the Californian mountains peaks. Plants collected in Colorado at Summit Lake, altitude 3917 m, 10 July 1988, S. J. Darbyshire 3850, (CAN 535149, illustrated in the image library) and a collection from Colorado: La Plata County, San Juan National Forest, 37°38'N, 107°37'W, on rock ledges below the summit of Eoleus, elevation 13,900 feet, 29 July 1962, Joan Michener 887, (COLO 181103), match collections from the White Mountains of California, although most collections from the Rocky Mountains are larger and appear to occur in a wider range of habitats. Festuca brachyphylla subsp. coloradensis appears to be almost as phenotypically plastic as subsp. brachyphylla.

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 and New Mexico indicates that the taxon occurs at altitudes above 2800 m. In August 1988, 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 plants of the later taxon 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).

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. • Leaf anatomy. Leaf cross section of F. brachyphylla subsp. coloradensis based on the average of 10 samples from collections in California. Leaf blades are 0.35–0.65 mm wide and 0.35–0.95 mm deep, with 3–5(-7) veins. Adaxial to abaxial sclerenchyma strands are absent. Abaxial sclerenchyma strands are poorly developed, in discrete, relatively narrow bands opposite the veins, but sometimes more strongly developed than in arctic specimens of subsp. brachyphylla. There is one well defined rib and 2–4 variously defined lateral ribs. • 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 strands are poorly developed, in discrete, relatively narrow strands opposite the 1 well defined rib and 2–4 variously defined lateral ribs. • Holotype specimen: C. Type specimen of F. brachyphylla subsp. coloradensis, scanned from Frederiksen, S. (1982, with permission). U.S.A. Colorado: Summit Co., Hoosier Ridge, 18 August 1960, K.A. Holmen, A.E. Porsild, & Weber fix 850. C. • Type specimen of name in synonymy: CAS. Type specimen of F. brachyphylla subsp. breviculmis, scanned from Frederiksen, S. (1982, with permission). U.S.A. California: Inyo Co, Mono Mesa, 24 July 1946, J. Th. Howell 22706. CAS. • Colorado Herbarium specimen. Plants of F. brachyphylla subsp. coloradensis collected in Colorado that are similar to the type of F. brachyphylla subsp. breviculmis published by Frederiksen (1982). • Arizona Herbarium specimen. Festuca brachyphylla subsp. coloradensis collected in Arizona. • 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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