Multitribe: Answers to key questions leading to this tribe. 

	Mature inflorescence, if breaking into units, then the units not as below; NOT [Mature inflorescence breaking into spikelet units consisting of a sessile fertile spikelet, a hairy pedicel with or without a sterile spikelet at tip, and a hairy rachis joint, all arising at the same point (a node) in specialized panicle branches called rames]
	Spikelets not as below; sterile florets if present, either located distal to the fertile floret(s) on the rachilla or paired and attached at the base of a single fertile floret, not paired with the upper glume as below; lemma and palea variously textured, enclosing the flower or not; disarticulation usually above the glumes; NOT [Spikelets usually dorsally compressed, appearing 1-flowered but containing 1 fertile floret and 1 sterile floret, the latter attached to the base of fertile floret opposite the upper glume, resembling the upper glume, and together with the upper glume enveloping the fertile floret; lower glumes minute (sometimes absent) to 3/4 as long as upper glumes and typically wrapping most of the way around the pedicel at base; fertile floret seed-like with chartaceous-indurate lemma and palea enclosing flower and fruit; disarticulation below the glumes with rare exceptions]
	Spikelets 1 to many-flowered, subtended by a pair of glumes (only 1 on lateral spikelets in Lolium); palea margins enclosed or not; plants of dry or wet habitats; NOT [Spikelets 1-flowered, lacking glumes; margins of the palea tightly enclosed by the lemma margins on female or perfect florets; plants of wetlands, often emergent aquatic]
	Inflorescence not as below; if a terminal spike, then the lateral spikelets attached edgewise to the rachis with inner (upper) glume wanting (as in Lolium); NOT [Inflorescence a terminal spike with sessile or subsessile spikelets attached broadside at nodes on opposite sides of the rachis]
	Lemmas and lemma awns not as below; if lemma indurate and enveloping the floret, then glumes distinctly dorsally compressed and calluses glabrous (as in Milium); NOT [Lemmas stiff to indurate, firmer than the glumes, surrounding the palea and often overlapping along the margins, closed at the tip as well as at the base, often pubescent; lemma awns (caducous or wanting in some species) terete and encircled at the base by the closed tip of the lemma; calluses usually pubescent, rarely glabrous]

Group1: Answers to key questions leading to this group. 

If plants mat-forming, then inflorescences not as below; NOT [Mat-forming annuals or perennials either with clusters of spikelets hidden by sharp-pointed leaves at branch tips, or with pistillate inflorescences consisting of burs partially hidden within expanded leaf sheaths with only the staminate inflorescences exceeding the upper leaves]

Inflorescence consisting of spike-like panicle branches with sessile- subsessile, closely imbricate, regularly-spaced, parallel spikelets all directed toward 1 side of the branch like the teeth of a comb (loosely so in Bouteloua curtipendula); fertile florets 1 per spikelet; NOT [Inflorescence not as above, the spikelets usually on pedicels in panicles that range from spike-like to open; if spikelets sessile, then they either have more than 1 fertile floret per spikelet or are not arranged like the teeth of a comb]

Bouteloua: Answers to key questions leading to this genus. 

Glumes unequal, the lower glume distinctly narrower and shorter than the upper glume, upper (exterior and longer) glume (2.5) 3.5-25 mm long; ligules <= 3 mm long, a fringe of hairs with or without a membranous base; NOT [Glumes subequal, D-shaped in side view, about 3 mm long; ligules 5-11 mm long, membranous, entire or lacerate]

Plants slender, 0.7-8 dm high; rhizomes absent or slender; panicle branches erect to reflexed; upper glumes (2.5) 3.5-8 mm long; lemma apex with 3 excurrent nerves or 3 awns up to 6 mm long; ligules up to 0.5 mm long; NOT [Plants coarse, 3.5-20 (25) dm high; rhizomes present and thick (1.5-8 mm wide); panicle branches erect to ascending; upper glumes 6-25 mm long; lemma apex unawned, obtuse to slightly rounded, sometimes lobed at tip; ligules 0.5-3 mm long]

Gracilis: Answers to key questions leading to this species 

Culms with 1-3 (6) panicle branches, these terminating in a spikelet; spikelets (20) 40-130 per branch; anthers yellow or purple; disarticulation above the glumes; culms tufted, often sod-forming, rhizomes, if present, short; NOT [Culms with more than 6 (usually >20) panicle branches, these terminating in a 3-5 mm long point rather than a spikelet; spikelets fewer than 7 (15) per branch; anthers usually red to red-orange; disarticulation at base of branches; culms solitary or in small groups from long rhizomes]