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

LOLIUM/POACEAE
973
Charmet et al. 1997; Gaut et al. 2000; Torrecilla & Catalán 2000), it is not yet clear what is the
best arrangement of these genera (i.e., one large genus, a number of smaller genera, etc.). We are
therefore following recent authors (e.g., Yatskievych 1999; Terrell ined.) in continuing to recognize
Lolium and retaining subgenus Schedonorus in Festuca, at least for the present. As more
information becomes available, a reassessment of generic boundaries may be necessary. See generic
synopsis of Festuca for more detail. Lolium is well known (e.g., Terrell 1966; Loos 1993a;
Charmet et al. 1996) to contain both cross-pollinated (e.g., L. perenne) and self-pollinated species
(e.g., L. temulentum). (Old Latin name for darnel, Lolium temulentum, apparently first
mentioned in Virgil’s Georgics—Terrell ined.) (subfamily Pooideae, tribe Poeae)
REFERENCES: Terrell 1966, 1968a, ined.; Bulinska-Radomska & Lester 1985a, 1988; Loos & Jarvis
1992; Darbyshire 1993; Loos 1993a, 1993b, 1994; Charmet et al. 1996, 1997; Tucker 1996;
Zwierzykowski & Naganowska 1996; Aiken et al. 1998; Pasakinskiene et al. 1998; Gaut et al.
2000; Torrecilla & Catalán 2002.
1. Glume markedly shorter than rest of the spikelet, 1/3 to 2/3 as long, (4–)5–10(–12) mm long;
lower lemmas firmly membranous basally; florets (2–)5–15(–22) per spikelet; plants annuals to
short-lived perennials _____________________________________________________________ L. perenne
1. Glume ca. 3/4 as long as to longer than the rest of the spikelet (excluding awns), 5–25 mm long;
lower lemmas hard basally OR not so; florets (2–)4–10(–11) per spikelet; plants annuals.
2. Spikelets � sunken in thickened axis of inflorescence and partly concealed by glumes; lower
lemmas firmly membranous basally, usually awnless or with an awn to 3(–10) mm long; caryopsis
3–5 times longer than wide; species rare, if present, in East TX ________________________ L. rigidum
2. Spikelets not sunken in thickened axis of inflorescence, not partly concealed by glumes; lower
lemmas hard basally, usually awned, but varying from awnless to with awn 5–18(–23) mm
long; caryopsis 2–3 times longer than wide; species widely scattered in East TX __________ L. temulentum
Lolium perenne L., (perennial), PERENNIAL RYE GRASS, ENGLISH RYE GRASS. Annual or short-lived
perennial forming tufts or clumps; culms 25–100(–120) cm tall; ligule 0.5–3 mm long; inflorescence
5–25(–30) cm long; spikelets usually 5–15 mm long excluding awns; glume (4–)5–10(–12)
mm long, 1/3–2/3 as long as spikelet; lemmas awned or awnless. Cultivated for winter-green
lawns, erosion control, and forage, escaped to roadsides, disturbed areas; throughout TX;
throughout most of Canada and the U.S. Mar–Jun. Native of Eurasia. Humphries (1980), Wilken
(1993b), and Terrell (ined.) treated the following two varieties as distinct species, while Kartesz
(1994, 1999) and Diggs et al. (1999) recognized them as subspecies. Gould (1975b), however, did
not recognize infraspecific taxa, and indicated that, “Texas plants exhibit much variation in
plant and spikelet size and may have awnless or awned lemmas. The grouping of these plants
into more than one species does not appear justifiable, and even recognition of two varieties is
not satisfactory.” Hatch (2002) also combined them into one species without recognizing infraspecific
taxa. Recently, Turner and Nesom (2000) discussed the use of the categories variety
and subspecies. After analyzing the morphological variation seen in East TX material, considering
the fact that the two freely hybridize and intergrade (Humphries 1980; Terrell ined.), and
contemplating the use of the categories variety and subspecies, recognition of the taxa as varieties
seems most appropriate. We are thus following a number of recent authorities (e.g., Jones et
al. 1997; Yatskievych 1999) in treating the variation within this species at the varietal level.
However, considering that these two introduced entities are maintaining more or less distinct
morphologies even when sympatric, a detailed study is needed to determine whether treatment
as separate species might indeed be more appropriate. According to Hitchcock (1935,
1951), this species was the first pasture grass to be cultivated in Europe, and it is considered one
of the best pasture species in temperate regions (Clayton & Renvoize 1986). While widely
planted for forage or hay, there are potential problems in livestock (e.g., tremors, staggers, “ryegrass
staggers”) if plants are infected with an endophytic (= growing within the plant tissue)