1	Panicle open to contracted with obvious, spaced branches; spikelets usually subtended by a solitary bristle (some lacking a bristle, or rarely with up to 3)		(2)
+	Panicle densely spikelike with congested branchlets, sometimes lobed; spikelets subtended by several to many bristles		(8)
2 (1)	Leaf blades plicate, fusiform-lanceolate to linear-lanceolate, narrowed toward base		(3)
+	Leaf blades flat, not plicate, linear or linear-lanceolate, straight or rounded at base		(4)
3 (2)	Leaf blades 2–7 cm wide; panicle branches up to 20 cm long; lower glume 1/3–1/2 spikelet length, usually acute to obtuse; lower lemma with narrow falcate apex, longer than upper lemma.		1 S. palmifolia
+	Leaf blades 1–3 cm wide; panicle branches up to 8 cm long; lower glume 1/4–1/3 spikelet length, usually broadly obtuse to truncate; lower lemma equaling upper lemma.		2 S. plicata
4 (2)	Upper glume subequaling spikelet; only branch or branchlet tips extending into a bristle, rarely a solitary bristle below a few spikelets.		3 S. yunnanensis
+	Upper glume distinctly shorter than spikelet; most spikelets subtended by one or more bristles		(5)
5 (4)	Tufted annual; upper lemma coarsely rugose.		4 S. intermedia
+	Perennials, sometimes rhizomatous; upper lemma smooth or finely punctate-rugose		(6)
6 (5)	Plant tufted; bristles stiff, stout; lower floret usually staminate with well-developed palea.		5 S. forbesiana
+	Plant with long scaly rhizomes; bristles slender; lower floret neuter with reduced palea		(7)
7 (6)	Spikelets elliptic; lower lemma equal to spikelet; upper lemma smooth, shiny.		6 S. chondrachne
+	Spikelets lanceolate; lower lemma slightly shorter than spikelet; upper lemma punctate-rugulose.		7 S. guizhouensis
8 (1)	Each branchlet from the main axis with only one mature spikelet; upper glume up to 1/2 as long as spikelet, upper floret clearly exposed		(9)
+	Each branchlet from the main axis with several mature spikelets; upper glume 2/3 as long to equaling spikelet		(10)
9 (8)	Spikelets (2.2–)2.5–3.5 mm; lower floret often staminate, its palea ovate, as wide as upper floret; upper lemma coarsely rugose.		8 S. pumila
+	Spikelets 1.8–2.3(–2.5) mm; lower floret neuter, its palea lanceolate, much narrower than upper floret; upper lemma finely rugose.		9 S. parviflora
10 (8)	Upper glume 2/3–3/4 length of fertile floret, upper lemma exposed above it; spikelets 2.8–3 mm, acute.		10 S. faberi
+	Upper glume subequaling fertile floret, almost completely covering upper lemma; spikelets 2–2.5(–3) mm, usually obtuse		(11)
11 (10)	Upper floret falling free from the glumes and lower lemma at maturity; cultivated plant.		11 S. italica
+	Upper floret retained within spikelet, this falling whole; wild plants		(12)
12 (11)	Bristles retrorsely scabrous.		14 S. verticillata
+	Bristles antrorsely scabrous		(13)
13 (12)	Spikelets 2–2.5 mm; lower glume 1/4–1/3 as long as the spikelet, usually obtuse.		12 S. viridis
+	Spikelets 2.5–3 mm; lower glume ca. 1/2 as long as the spikelet, acuminate.		13 S. arenaria