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Published In: Species Plantarum 1: 73. 1753. (1 May 1753) (Sp. Pl.) Name publication detailView in BotanicusView in Biodiversity Heritage Library
 

Project Name Data (Last Modified On 8/27/2009)
Acceptance : Accepted
 

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75. Festuca L. (fescue)

Plants perennial, sometimes with rhizomes, forming tufts, clumps, or loose colonies. Flowering stems erect or ascending, sometimes from spreading bases, glabrous. Leaf sheaths open nearly to the base (closed nearly to the tip in F. rubra), the ligule relatively short, truncate or slightly concave. Leaf blades flat, folded, or with inrolled margins, with flat, sharply pointed tips. Inflorescences open or narrow panicles with ascending to spreading or downwardly angled branches, these sometimes arched or curved, the spikelets single or in small clusters toward the branch tips, but not regularly paired, all similar in size and appearance and with fertile florets (rarely some of the florets replaced with vegetative bulblets in F. arundinacea). Spikelets elliptic‑lanceolate to ovate in outline, somewhat flattened, with 3–10 florets. Glumes shorter than the rest of the spikelet, pointed at the tip, awnless, glabrous or rarely roughened or hairy, the lower glume shorter, 1‑nerved, the upper glume 3‑ or 5‑nerved. Lemmas sharply pointed or less commonly bluntly pointed to rounded at the tip, often awned, rounded on the back, faintly to strongly 3‑ or 5‑nerved with the nerves converging (arched inward) toward the tip, glabrous (hairy in some forms of F. rubra). Paleas as long as or slightly longer than the lemmas, narrowly elliptic. Stamens 3, the anthers yellow. Ovaries sometimes hairy at the tip. Fruits oblong‑elliptic in outline, nearly circular in cross‑section, with a narrow groove along 1 side. About 450 species, worldwide, especially in temperate regions.

Generic limits among Festuca and its relatives remain controversial. Most botanists accept the separation of the annual fescues into the genus Vulpia, although a few non‑Missouri species are intermediate between the two groups for some characters. A more difficult problem is the relationship between Festuca and Lolium. Traditionally, these have been easily separable because of the spicate inflorescence and single glume of Lolium, as opposed to the paniculate inflorescence and pair of glumes in Festuca. Recent studies involving a number of independent lines of evidence, including hybridization experiments, cytogenetic details, examination of leaf anatomy, seed protein analysis, and investigation of chloroplast DNA restriction site variation (reviewed by Darbyshire, 1993) have shown that the traditionally classified Festuca subgenus Schedonorus (P. Beauv.) Peterm. (represented in the Missouri flora by the widespread, introduced F. arundinacea and F. pratensis) is more closely related to Lolium than to Festuca subgenus Festuca (which includes the rest of the Missouri species of perennial fescues). Darbyshire (1993) concluded that subgenus Schedonorus should be transferred to Lolium and published the necessary new combinations under that genus. However, questions remain about the appropriate level at which to recognize these groups (Aiken et al., 1997). It may prove more acceptable to combine all of them into a single, broadly defined, genus or to recognize all three as distinct genera, once other subgenera of Festuca have been studied in more detail. Thus, it seems most expedient to retain the traditional classification of Festuca (to include subgenus Schedonorus) for now, with the caveat that future studies may require large‑scale changes in the generic delimitation of Festuca.

Several species of Festuca and Lolium are susceptible to fungi of the ascomycete family Clavicipataceae (which also can infect some species of Cyperaceae and Juncaceae). These fungi are systemic, perennial endophytes (living inside the host plants) that have developed a mutualistic relationship with their hosts, in which the fungi both allow the grasses to grow and reproduce more effectively and provide a defense against herbivory by producing toxic alkaloids (Clay, 1988). In exchange, the fungi live within the grasses and are spread with the host seed. In Missouri, the principal fungi involved are the asexually reproducing Acremonium coenophialum Morgan‑Jones & W. Gams and a related, sexual species Epichloe typhina (Pers.)Tul., both of which commonly infect F. arundinacea and F. rubra as well as other grasses (Aiken and Darbyshire, 1990). Related species infect Lolium. The alkaloids produced by the fungi result in various responses in insects, including avoidance of the plants, reduced feeding and egg‑laying, reduced growth, and delayed maturation (Clay, 1988). Of more direct economic impact are the potential effects on herbivorous mammals, including livestock. The symptoms in cattle are known as “summer syndrome” or “summer slump” and include reduced weight gain, reduced milk output in dairy cattle, and increased body temperature (Ball et al., 1993). Cattle whose diets include infected grasses frequently are seen standing in farm ponds during the summer months, in response to heat stress. In severe cases, intoxication can result in spontaneous abortions (especially in horses), “staggers and shivers,” and “fescue foot,” a type of gangrene that develops on the extremities (Clay, 1988; Ball et al., 1993). Nationally, the impact of this problem on the livestock industry has been estimated as between $500 million and $1 billion annually (Ball et al., 1993). Oddly enough, because of improved performance and increased drought resistance, infected stocks of fescues are considered superior for lawns and other turf applications. Several resistant strains of fescues have been developed, but much of the F. arundinacea in Missouri pastures potentially contains the fungi. Land managers who suspect their cattle are being poisoned should rotate their stock frequently to uninfected sites, such as native, warm‑season grass plantings.

 

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1 Leaf blades 0.3–2.0 mm wide, usually folded or with inrolled margins (2)
+ Leaf blades 3–12 mm wide, flat (4)
2 (1) Leaf sheaths closed nearly to the tip, the uppermost persistent, the basal sheaths becoming shredded into brown, stringy fibers at maturity 5 Festuca rubra
+ Leaf sheaths open nearly to the base, persistent, sometimes turning light brown at maturity, but not becoming shredded into fibers (3)
3 (2) Spikelets 5–7 mm long; anthers 2.0–2.5 mm long 2 Festuca ovina
+ Spikelets 7–10 mm long; anthers 2.5–3.0 mm long 8 Festuca trachyphylla
4 (1) Lemmas 3–5 mm long; anthers 1.0–1.6(–2.0) mm long (5)
+ Lemmas 5–9 mm long; anthers 1.8–4.0 mm long (6)
5 (4) Lowermost inflorescence branches with clusters of 8–20, strongly overlapping spikelets toward the tip; spikelets 4–5 mm wide, obovate before flowering (ovate to obovate at maturity) 3 Festuca paradoxa
+ Lowermost inflorescence branches with 2–7 spikelets toward the tip, these mostly widely spaced and not or only slightly overlapping; spikelets 2–4 mm wide, lanceolate before flowering (ovate to obovate at maturity) 7 Festuca subverticillata
6 (4) Leaf blades without auricles at the base; spikelets with 3 or 4(5) florets; lemmas roughened 6 Festuca sororia
+ Leaf blades with a pair of short auricles at the base; spikelets with (3)4–9 florets; lemmas glabrous or slightly roughened only near the tip (7)
7 (6) Auricles sparsely to densely hairy along the margins; spikelets with (3)4–6 florets; lemmas 7–10 mm long 1 Festuca arundinacea
+ Auricles glabrous; spikelets with (4–)6–10 florets; lemmas 4–7 mm long 4 Festuca pratensis
 
 
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