Tribe XII Spikelets all of one kind A. Spikelets sunken in the cavities of the flattened corky rachis (Stenotaphrum) AA. Spikelets not sunken in the rachis B. Spikelets subtended or surrounded by 1 to many distinct or more or less connate bristles C. Bristles persistent, the spikelet deciduous) (Setaria) CC. Bristles falling with the spikelet at maturity Bristles united into a burlike involucre, the bristles retroously barbed (Cenchrus) BB. Spikelets not subtended by bristles D. Glumes or sterile lemma awned, inflorescence paniculate; spikelets silky (Rhepachelytrium) DD. Glumes and sterile lemma awnless E. Fruit flexible, usually dark colored, lemma with white hyaline margins Spikelets in slender racemes more or less digitate at the summit of the culms (Digitaria) EE. Fruit rigid Spikelets placed with the back of the fruit turned towards the rachis of the spike-like racemes Fruit not long acuminate; at least one glume present F. First glume wanting; spikelet plano-convex (Paspalum) FF. First glume present, spikelets in panicles, culms herbaceous (Panicum)