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

1090 POACEAE/UROCHLOA
�Triticosecale hybrids, the result of hybridization between Triticum and Secale, “are becoming
increasingly important as cereal crops” (Barkworth ined.). While sometimes treated within
Tr iticum (e.g., Gould 1975b; Hatch 2002), Aegilops appears to be morphologically, ecologically,
and phylogenetically distinct (van Slageren 1994; Morrison ined.; Saufferer ined.) and is widely
recognized as a separate genus (e.g., Yatskievych 1999; Morrison ined.; Saufferer ined.). The
Triticeae has a complex evolutionary history and there is still no general agreement on generic
concepts in the tribe (Barkworth 2000). (The classical name for wheat, possibly from Latin:
tritus, rubbed, in reference to the rubbing or threshing needed to separate the grain from the
chaff—Zimdahl 1989) (subfamily Pooideae, tribe Triticeae)
REFERENCES: Bowden 1959; Helbaek 1966; Baum 1982, 1978, 1983; Waines et al. 1982; Löve 1984,
An et al. 1985; Gupta & Baum 1986, 1989; Waines & Barnhart 1992; Zohary & Hopf 1994;
Tucker 1996; Barkworth 2000; Mason-Gamer & Kellogg 2000; Campbell ined.
Triticum aestivum L., (summer), BREAD WHEAT, WHEAT, COMMON WHEAT. Glabrous annual 40–
120 cm tall; culm with internodes usually hollow; ligule a membrane 2–3 mm long; leaf blades
prolonged at base into 2 narrow, thin, early-withering, pointed auricles on summit of leaf
sheath; spike terminal, unbranched, rather stiff, bilateral, dense, usually 5–12 cm long (excluding
awns if present) and ca. 1 cm thick, the spikelets sessile, solitary at each node, borne on opposite
sides of the zigzag persistent spike axis (the axis not disarticulating, even under pressure);
spikelets ca. 8–15 mm long, 2–5(–9)-flowered, only the lower 2 or 3(–5) florets perfect;
glumes � equal, broadly ovate, (3–)3.6–6.5 mm wide, asymmetrical, 3(–more)-veined, loosely
enclosing the florets, awnless or with awn to 60 mm or more long; lemmas broad, slightly
keeled, awnless or with awn to 150 mm or more long. Commonly cultivated, sometimes
planted for erosion control near construction sites, frequently seen as a transitory escape along
highways, railroads, and waste places; scattered throughout TX; throughout most of Canada
and the U.S. Apr–May. Along with RICE and CORN, WHEAT is one of the three most important
food plants for humans worldwide. It is used to make bread flour, pastry-grade flour, Orientalstyle
soft noodles, and cereals (Campbell ined.). It is a hexaploid (= 6 sets of chromosomes) species
believed to have originated in sw Asia through hybridization between the wild diploid
Aegilops squarrosa L. and a tetraploid cultivated species, Tr iticum turgidum L. (RIVET WHEAT)
(Zohary & Hopf 1994). Like many other cultivated species (e.g., CORN, SUNFLOWER), WHEAT has
been artificially selected for retention of the fruits on the inflorescence and thus less loss of the
grain crop—therefore disarticulation of the inflorescence does not occur as in non-domesticated
members of the genus. WHEAT is sometimes infected by the rust fungus Puccinia
graminis Pers. (black stem rust of wheat) which can cause significant economic losses; this heterecious
(= using more than 1 host to complete its life cycle) rust also infects some species in the
genus Berberis (e.g., the introduced B. vulgaris L.—EUROPEAN BARBERRY). Because of this, the sale
or transport of certain BARBERRY species is illegal in the U.S. and Canada. WHEAT pollen is reported
to cause hay fever (Steyermark 1963). I
UROCHLOA P. Beauv. SIGNAL GRASS, LIVER-SEED GRASS, PARA GRASS
Annuals or perennials, often rooting at lower nodes; ligule a ciliate membrane 2 mm or less
long; leaf blades flat, rounded or abruptly narrowed basally; inflorescence a panicle, the primary
spike-like branches rebranched or unbranched (inflorescence sometimes resembling that of
Panicum or Paspalum), terminating in a spikelet (unlike those of Paspalidium or Setaria
which terminate in a bristle), the spikelets conspicuously arranged on one side of the branches
or not so; inflorescence branches and pedicels often with some long whitish hairs; spikelets
usually awnless or with only minute awns, 2-flowered, the lower floret sterile or staminate, the
upper perfect; disarticulation below the glumes; glumes usually both present, the first shorter
(ca. 1/5–3/4 as long as the second); lower lemma resembling upper glume; lemma of perfect
floret hardened, glabrous, usually roughened-rugose, with inrolled margins; stamens 3.