17. Tribe Triticeae Dumort.

Plants with C₃ photosynthesis, annual or perennial. Aerial stems annual, not woody, erect or ascending, sometimes arched, unbranched or branched near the base. Ligules membranous, the margin sometimes uneven. Inflorescences consisting of a single terminal, dense spike or raceme, the main axis persistent or sometimes breaking apart into joints at maturity, the spikelets 1–4 at each node and positioned with a flat side against the axis, sometimes in clusters of 1 fertile and (1)2 sterile, reduced spikelets, the central spikelet sometimes appearing subtended by awnlike bristles, disarticulating above or below the glumes, or shed intact with the joints of the main axis. Spikelets with 1–7 perfect florets, the axis sometimes extended past the florets, usually as an awnlike bristle. Glumes 2, often hard or leathery in texture, sometimes awnlike. Lemmas rounded or keeled. Paleas shorter than the lemmas, usually strongly 2‑keeled Stamens 3, the anthers (in Missouri material) yellow to pale yellow. (One)15–30 genera, about 350 species, nearly worldwide, but most diverse in temperate regions of the Northern Hemisphere.

The Triticeae are a very close‑knit group that is easily recognized among Missouri grasses. However, generic classification within the tribe remains highly controversial. Even the available evidence from various molecular studies is discordant (Kellogg et al., 1996). The present treatment is relatively conservative and includes only six genera for the state. Readers should note that a more highly dissected classification (Baum, 1982, 1983; Barkworth and Dewey, 1985; Kellogg, 1989) is beginning to gain broader acceptance among botanists. Although the recognition of an increased number of genera presumably results in more natural phylogenetic groups, several practical considerations make application of such a classification difficult in a floristic manual. These include the fact that the generic segregates are mostly defined by cytogenetic (genomic), rather than morphological, characters and that hybridization is rampant between the genomically defined groups. Where appropriate, segregate genera are discussed as part of the treatments below.