keys to the vascular plants of east texas - Botanical Research ...

FESTUCA/POACEAE
951
rachilla glabrous; shortest branch (if more than one) at each main node of inflorescence with
only 1–2 spikelets; lowest inflorescence node with 1 or 2 branches _______________________ F. pratensis
1. Inflorescence open, with lower branches usually without spikelets below the middle; spikelets
4–9 mm long, with 2–5(–6) florets; lower lemmas 3–7(–8) mm long; native species of open woods,
forest margins, or other partially shaded places.
3. Lower lemmas 5–8 mm long, awnless or with minute awn to 1.5(–2) mm long; upper glume
4–7.5 mm long; species ranging from ne part of East TX south to e Edwards Plateau __________ F. versuta
3. Lower lemmas 3–5 mm long, awnless; upper glume 2–5 mm long; species limited to the n
and ne parts of East TX.
4. Inflorescence branches reflexed or drooping at maturity; spikelets often widely separated
on the lower inflorescence branches, sometimes overlapping slightly toward the ends of
the branches; spikelets lanceolate in bud; upper glume usually shorter than the first lemma
______________________________________________________________________ F. subverticillata
4. Inflorescence branches loosely ascending at maturity (can be drooping before maturity);
spikelets clustered, consistently overlapping each other by 1/3 to 1/2 their length on the
lower inflorescence branches; spikelets clavate in bud; upper glume almost as long as or
longer than the first lemma ____________________________________________________ F. paradoxa
Festuca arundinacea Schreb., (reed-like), TALL FESCUE, ALTA FESCUE. Nearly glabrous perennial
forming clumps, with short rhizomes; culms 60–150(–200) cm tall; ligule 0.2–1 mm long; leaf
blades 3–12 mm wide, with veins prominent on adaxial (= upper) surface; panicle rather narrow
and dense; spikelets 8–15(–20) mm long; some florets are reportedly replaced on occasion
by vegetative bulbils (Yatskievych 1999); anthers 2.5–4 mm long; chromosome number variable—2n
= 28, 42, 56, 63, 70 (Darbyshire ined.). In calcareous clay, roadsides, open or disturbed
areas, also cultivated; widespread in East TX but more common in the ne part; widely scattered
in TX; s Canada and nearly throughout the U.S. Mostly Apr–Jun. Native of temperate Eurasia
and n Africa. [F. elatior L. var. arundinacea (Schreb.) Wimm., F. elatior L. subsp. arundinacea
(Schreb.) Hack., Lolium arundinaceum (Schreb.) Darbysh., Schedonorus arundinaceus (Schreb.)
Dumort., Schedonorus phoenix (Scop.) Holub] Darbyshire (1993) presented evidence that
Festuca is polyphyletic and that this species is best treated in the genus Lolium; Jones et al.
(1997) and Kartesz (1999) followed Darbyshire (1993). More recently, Darbyshire (ined.) has
transferred the species to Schedonorus under the name S. phoenix. However, there is conflicting
evidence (Aiken et al. 1997; Charmet et al. 1997; Gaut et al. 2000), and until the taxonomic situation
is more stable, we are treating the species conservatively and continuing to recognize it in
Festuca (see additional discussion in generic synopsis above).
This species, introduced as a cool-season hay/forage, is considered to be one of the most important cultivated
pasture grasses in the U.S. It is now also used as a turf grass and for erosion control, and it is reported
to occupy more acreage in the U.S. than any other introduced grass species (Ball et al. 1993). However, it can
be a problematic invasive weed in native prairie remnants. Livestock can sometimes be poisoned by eating
this species, with the resulting condition variously called “fescue toxicity,” “gangrenous fescue poisoning,”
“fescue foot,” “summer syndrome,” “summer slump,” “summer toxicosis,” “fat necrosis,” or “staggers and
shivers.” While the symptoms are similar to those produced by ingestion of ergot alkaloids (see discussion
under genus Secale), a different endophytic (= growing within the plant tissue) fungus is at fault. The fungus
infecting fescue has been identified as Neotyphodium coenophialum (Morgan-Jones & W. Gams)
Glenn, C.W. Bacon & Hanlin (previously in genus Acremonium), a relative of ergot fungi. The fungus produces
alkaloids (including ergot-like and pyrrolizidine) which cause a number of symptoms (e.g., low
weight gain, reduced milk production, increased body temperature, intolerance to heat, abortion). A number
of these symptoms are caused by vasoconstrictive action in small blood vessels, which reduces blood
flow to the skin and extremities—even gangrene and loss of extremities (e.g., feet, tip of tail, tips of ears) can
occur (Kingsbury 1964; Clay 1988; Hardin & Brownie 1993; Weathers 1998; Yatskievych 1999; Burrows &
Tyrl 2001; Hart et al. 2001). According to Burrows and Tyrl (2001), “Diseases associated with fescues are
probably the most important toxicologic problems of livestock in North America” and conservative estimates
of livestock-related losses nationwide are between 1/2 and 1 billion dollars per year (Ball et al. 1993).