In this genus, for keying it is important to use mature spikelets. The spikelets continue to grow significantly after emergence of the inflorescence.

A. Rare in our area, E. secundiflora uniquely has second glumes and lemmas > 2.5 mm long.

A. If the dimensions are smaller, proceed with the key:

1. Plants (sheaths, glumes, lemmas) glandular OR with long cilia on the paleas. Inflorescences pencil-shaped or cylindric, usually < 4 cm in diameter…2

1. Plants not glandular, and paleas without long conspicuous marginal cilia (or with tiny cilia < 0.1 mm long). Inflorescences elliptic or ovate, usually (but not always) > 4 cm in diameter…3

2. Inflorescence narrow, so tightly congested as to hide the branches and pedicels, the shape and size of a pencil to cigar, resembling a furry tail (usually < 2 cm diam.)…E. ciliaris

2. Inflorescence usually 1- 5(7) cm wide, cylindric…E. amabilis (usually encountered as a small weed in open, sandy, highly disturbed places)

3. Glumes equal or nearly so, both glumes slightly longer than 1 mm (usually ca. 1.3 mm). Leaf blades 3-8 mm wide. (Note: glumes subequal also in E. atrovirens but its glumes 1.2-1.7 mm and the pulvinus glabrous. Glumes subequal may occur in E. scaligera but this with the inflorescence < 15 cm vs. > 25 cm long)…E. spectabilis (Inflorescences often purplish, branch bases with a tuft of hairs, the bases often included in subtending leaf base. Anthers 2)

3. Glumes unequal, or if equal not ca. 1.3 mm long; leaf blades usually < 5 mm wide…4

4. Lower glume 0.3-0.6 mm…E. pilosa (glumes extremely unequal; spikelet usually < 6 mm long; anthers 3)

4. Lower glume > (0.5)0.7 mm…5

5. Pedicels longer than spikelets AND spikelets erect on branches…E. elliottii

5. Pedicels shorter than or equal to spikelets; spikelets usually appressed to branches (spikelets may angle outward from branch but then the pedicels shorter than or equal to the spikelets)…6

6. Main inflorescence branches with long hairs at the bases…E. refracta

6. Main inflorescence branches glabrous (or nearly so) at the bases…7

7. Culms > 75 cm tall with the lowest inflorescence branch > 30 cm above the basal leaves. Leaf blades adaxially pilose. Bases of inflorescences branches bare…E. atrovirens (anthers 3)

7. Culms usually < 75 cm tall with the lowest inflorescence branches usually < 30 cm above the basal leaves. Leaf blades adaxially glabrous to ciliate. Bases of inflorescence branches often hidden by spikelets, or bare...8 [Eragrostis bahiensis infrequently exceeds 75 cm tall, but differs by having 2 vs. 3 anthers, by ranging to more florets per spikelet (8-30 vs. 10-22 florets), and by ranging to larger leaf blades less likely to be adaxially pilose: 12-40 cm X 2-5 mm vs. 8-20 cm vs. 2-3 mm.]

8. Leaf blades 4-8 cm X 1-2 mm. Lower glume > 1.4 mm. Upper glume (1.6) > 1.7 mm. Inflorescence 5-15 cm X 2-10 cm…E. scaligera (lemma 0.6-0.9 mm margin-to-keel vs. < 0.6 mm in E. pectinacea)

8. Leaf blades 12-40 cm X 2-5 mm. Lower glume < 1.4 mm. Upper glume < 1.7 mm; inflorescence 15-30 cm X 8-17 cm…E. bahiensis (E. gangetica similar but with smaller spikelets: 2-4.6 mm vs. > 6 mm)