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

TRISETUM/POACEAE
1089
low areas; nearly throughout TX but more common in the e part; e U.S. from MA s to FL w to NE
and TX. Late Apr–Jul, less commonly to Nov. This is a variable species sometimes divided into
varieties (de Wet et al. 1982) that are not clearly defined (Yatskievych 1999); if varieties are recognized,
all East TX material would fall into var. dactyloides. EASTERN GAMA GRASS is a valuable
native prairie grass, prized for both hay and grazing. It is sometimes referred to as an “ice cream
plant” because it is quickly targeted by grazing animals (H. McCarley, pers. comm.). m/306
TRISETUM Pers. FALSE OAT
AA C3 genus of ca. 75 species of temperate, subarctic, and alpine areas (Rumley ined.) worldwide
except Africa; it is apparently closely related to Koeleria (Tucker 1996) and is similar to
Sphenopholis. According to Rumley (ined.), “Trisetum differs from Sphenopholis, with which it
occasionally hybridizes, in having spikelets that disarticulate above the glumes (also below in a
few species), and awns that are inserted lower on the lemmas and are usually longer.” Some species
are cultivated as pasture grasses or for fodder (Watson & Dallwitz 1992). (Latin: tres, three,
and seta, a bristle, from the awned and 2-toothed lemma—i.e. three-awned appearance in the
type species, Tr isetum flavescens (L.) P. Beauv.—Rumley ined.) (subfamily Pooideae, tribe Poeae)
REFERENCES: Louis-Marie 1928; Tucker 1996; Rumley ined.
Trisetum interruptum Buckley, (interrupted, not continuous), PRAIRIE TRISETUM, PRAIRIE FALSE
OAT, PRAIRIE WEDGESCALE. Annual 7–50(–60) cm tall; leaf sheaths short scabrous to hispid or pilose;
ligule an asymmetrical, ragged-margined membrane (1–)1.5–2(–2.5) mm long; leaf blades
ca. 1–4 mm wide, flat; panicle (2–)5–10(–15) cm long, narrow, � spike-like, the branches short;
spikelets 2–3-flowered (upper floret often reduced and sterile), 3–6 mm long (excluding awns);
disarticulation below glumes and between florets; glumes subequal, ca. as long as the lemmas;
lemmas with 2 slender acuminate to usually bristle-like apical teeth ca. 1–1.5 mm long, also
awned from back at or just below base of the teeth, the awn 4–8 mm long, twisted and geniculate.
Disturbed sites; throughout much of TX; AZ, CO, LA, NM, OK, and TX. (Late Mar–)Apr–
May. Jones et al. (1997) and Hatch (2002) treated this taxon in the genus Sphenopholis as [S.
interrupta (Buckley) Scribn.]; however, we are following Rumley (ined., forthcoming Flora of
North America treatment) in recognizing it in Trisetum.
TRITICUM L. WHEAT
AA C3 genus of 4 (Mabberley 1997) to 10–20 (Tucker 1996) species, depending on the authority.
Many cultivated genera have such variation in the number of species due to differing taxonomic
interpretations (e.g., depending on whether the variation is recognized at the level of
species, subspecies, or variety). Triticum species range from the Mediterranean to Iran. The genus
is related to Aegilops, which may have contributed one or more genomes to polyploid
WHEAT (e.g., An et al. 1985). Worldwide, WHEAT (all species together) ranks first in grain production
and accounts for more than 20% of total food calories consumed by humans. WHEAT is also
the most widely cultivated plant in the world and is thought to have been one of the first two
cultivated plants (BARLEY—Hordeum vulgare, is the other); as such it was probably important in
the development of early civilization in the Near East (Heiser 1990). It is thought to have been
domesticated prior to 7,000 BC (Clayton & Renvoize 1986). WHEAT is superior to many other
grain crops because of its high (8–14%) protein content (Zohary & Hopf 1994); it is particularly
important for bread-making because gluten, the characteristic protein, makes bread dough
stick together and gives it the ability to retain gas, thereby making it ideal for making leavened
(or raised) bread (Heiser 1990). Triticum aestivum (BREAD WHEAT) is the most important temperate
cereal and represents ca. 90% of the total world WHEAT crop. Intergeneric hybrids with
many other members of the Triticeae are known including Aegilops, Agropyron, Elymus,
Elytrigia, and Secale (Watson & Dallwitz 1992; Saufferer ined.). For example, various