1	"Upper lemma obtusely rounded at apex and with distinct mucro; lower glume abaxial to spikelet bearing axis"	2
1	"Upper lemma obtuse to acute, usually muticous; lower glume adaxial to spikelet bearing axis"	4
2	"Lower glume c. 1/3 spikelet length"	"Urochloa panicoides"
2	"Lower glume at least 1/2 spikelet length"	3
3	"Lower glume 5-7-nerved"	"Urochloa oligotricha"
3	"Lower glume 3-nerved, rarely sub-5-nerved"	"Urochloa mosambicensis"
4	"Inflorescence ± open or with spikelets in several untidy rows; lower racemes sometimes branching"	5
4	"Inflorescence strictly regular and racemose with spikelets in two regular rows; lower racemes never branching"	10
5	"Plant with robust ascending culms 2-6 m tall, with stolons"	"Urochloa mutica"
5	"Plant with slender culms 1 m tall, without stolons"	6
6	"Spikelets c. 6 mm long"	"Urochloa foliosa"
6	"Spikelets less than 6 mm long"	7
7	"Spikelets c. 2 mm long"	"Urochloa reptans"
7	"Spikelets 3-4 mm long"	8
8	"Glumes and lower lemma with cross veins"	"Urochloa fasciculata {Urochloa fasciculata var. reticulata}"
8	"Glumes and lower lemma without cross veins"	9
9	"Spikelets hairy, 3.5-4.6 mm long; rachilla pronounced between glumes"	"Urochloa pubigera"
9	"Spikelets glabrous, 2.8-3.5 mm long; rachilla not pronounced between glumes"	"Urochloa praetervisa"
10	"Spikelets up to 3 mm long"	11
10	"Spikelets more than 3 mm long"	13
11	"Ligule a fringed membrane"	"Urochloa distachya"
11	"Ligule a fringe of hairs"	12
12	"Spikelets glabrous, not turgid"	"Urochloa kurzii"
12	"Spikelets sparsely hairy, ± turgid"	"Urochloa ramosa"
13	"Strong perennials"	14
13	"Annuals or weak perennials"	16
14	"Lower glume 3/4 to as long as spikelet"	"Urochloa humidicola"
14	"Lower glume 1/3-1/2 as long as spikelet"	15
15	"Rachis c. 2 mm wide, flattened; spikelets ± hairy"	"Urochloa decumbens"
15	"Rachis c. 0.75 mm wide, flattened to convex; spikelets glabrous"	"Urochloa brizantha"
16	"Lower glume 1/8-1/6 spikelet length"	17
16	"Lower glume 1/3-1/2 spikelet length"	18
17	"Spikelets 3-4 mm long"	"Urochloa occidentalis"
17	"Spikelets 4-5 mm long"	"Urochloa gilesii"
18	"Spikelets hairy"	19
18	"Spikelets glabrous"	25
19	"Spikelets with a subapical fringe of silky hairs"	20
19	"Spikelets evenly hairy or if with longer apical hairs these are not arranged in a fringe"	21
20	"Hairs of subapical fringe ± the same length; lower lemma not drawn out to an apical point"	"Urochloa argentea"
20	"Hairs of apical fringe of varying lengths; lower lemma drawn out to an apical point"	"Urochloa holosericea"
21	"Hairs increasing in length towards spikelet apex"	"Urochloa piligera"
21	"Hairs evenly distributed on spikelet"	22
22	"Spikelets more than 3.6 mm long"	23
22	"Spikelets less than 3.5 mm long"	24
23	"Spikelets 3.6-4.5 mm long; lower floret sterile"	"Urochloa atrisola"
23	"Spikelets 4.7-6 mm long; lower floret male"	"Urochloa texana"
24	"Pedicels without long white bristly hairs"	"Urochloa whiteana"
24	"Pedicels with long whitebristly hairs"	"Urochloa advena"
25	"Spikelets reddish; leaf margins serrate"	"Urochloa polyphylla"
25	"Spikelets green to yellow"	"Urochloa subquadripara"