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

950 POACEAE/FESTUCA
2–10 florets, glabrous or nearly so; disarticulation above glumes and between florets; glumes 2,
unequal, the upper one longer, usually slightly shorter than lower lemma; lemmas usually
rounded on back, not toothed at apex, awnless or with a short awn; stamens 3.
AA C3 genus of ca. 400–450 species (Mabberley 1997; Darbyshire & Pavlick ined.) of temperate,
alpine, and polar areas of all continents except Antarctica, and in tropical mountains. Some
are important as pasture and lawn grasses, while others are considered significant weeds (Watson
& Dallwitz 1992). Vulpia (SIXWEEKS GRASS, ANNUAL FESCUE), treated here as a separate genus,
has in the past sometimes been included in Festuca. A number of workers (e.g., Bulinska-
Radomska & Lester 1988; Pasakinskiene et al. 1998) have noted similarities between the genera
Festuca, Lolium, and Vulpia, and it now seems clear that Lolium is most closely related to some
species of Festuca (Gaut et al. 2000). In addition, intergeneric hybrids between Lolium and
Festuca are known (Terrell 1966; Watson & Dallwitz 1992). Darbyshire (1993) suggested that
Festuca subgenus Schedonorus, the broad-leaved fescues (including F. arundinacea and F.
pratensis), be shifted to Lolium based on a number of types of experimental evidence including
hybridization. Tucker (1996) followed that classification. More recently (Darbyshire ined.) has
recognized subgenus Schedonorus at the generic level and considers it to comprise 3 species
native to Europe and temperate Asia. However, other recent studies (e.g., Aiken et al. 1997;
Charmet et al. 1997; Gaut et al. 2000) suggest the situation is more complex. In fact, some molecular
data (e.g., Charmet et al. 1997) indicate that Lolium, Vulpia, and possibly Dactylis are
derived from within Festuca and even raise the possibility that Festuca might be polyphyletic.
A more recent study (Torrecilla & Catalán 2000) suggests that only Festuca in the broad sense
(including Lolium and Vulpia) is monophyletic. It is thus not yet clear what is the best arrangement
of these genera (i.e., one large genus, a genus with subgenera, a number of smaller genera,
etc.). We are therefore following such recent authors as Yatskievych (1999) in retaining subgenus
Schedonorus in Festuca, at least for the present. As more information becomes available, a
reassessment of generic boundaries may be necessary. Clayton and Renvoize (1986), while recognizing
the similarities between F. arundinacea (and related species) and Lolium, said, “Nevertheless
the two genera are so easily distinguished that it seems unrealistic to unite them.” Indeed,
the two genera are readily separated morphologically: Lolium has spicate inflorescences
and spikelets with a single glume, while Festuca has paniculate inflorescences and spikelets
with two glumes. The key below is in part modified from Aiken and Lefkovitch (1993). (Latin:
festuca, stalk, stem, or straw; a name used by Pliny for a weed—Darbyshire & Pavlick ined.) (subfamily
Pooideae, tribe Poeae)
REFERENCES: Piper 1906; Terrell 1966, 1967, 1968b; Bulinska-Radomska & Lester 1985b, 1988;
Aiken & Darbyshire 1990; Darbyshire & Warwick 1992; Aiken & Lefkovitch 1993; Darbyshire
1993, ined.; Tucker 1996; Aiken et al. 1997, 1998; Charmet et al. 1997; Soreng & Terrell 1997; Thomas
et al. 1997; Pasakinskiene et al. 1998; Gaut et al. 2000; Soreng et al. 2001; Torrecilla &
Catalán 2002; Darbyshire & Pavlick ined.
1. Inflorescence contracted, at least above, with lower branches often bearing spikelets well below
the middle; spikelets 8–15(–20) mm long, with 3–10 florets; lower lemmas 4–12 mm long; introduced
species usually of roadsides, fields, and disturbed or open areas.
2. Auricles at summit of leaf sheath usually with ciliate margins; spikelets usually with 3–6 florets;
leaf sheaths with age pale straw-colored, often staying intact; leaf blades 3–12 mm wide;
lemmas usually 6–12 mm long, usually minutely scabrous (use dissecting scope), with a short
awn 0.3–2(–4) mm long, rarely awnless; rachilla scabrous; shortest branch (if more than one)
at each main node of inflorescence usually with 3 or more spikelets; lowest inflorescence
node with 2 or 3 branches ____________________________________________________ F. arundinacea
2. Auricles at summit of leaf sheath with glabrous margins; spikelets usually with (4–)6–10 florets;
leaf sheaths with age brown, breaking down to form fibers; leaf blades 2–7(–8) mm wide;
lemmas usually 4–6(–8) mm long, usually glabrous or scabrous only at apex, usually awnless;