[*] Scales of the spikelet strictly 2-ranked, conduplicate and keeled.
[+] Flowers destitute of bristles and of beak to the achene, inflorescence terminal.
1. Cyperus. Spikelets few–many-flowered, usually elongated or slender.
2. Kyllinga. Spikelets 1-flowered (but of 3 or 4 scales), glomerate in a sessile head.
[+][+] Flower furnished with bristles; achene beaked; inflorescence axillary.
3. Dulichium. Spikelets 6–10-flowered, slender, clustered on an axillary peduncle.
[*][*] Scales of the several–many-flowered spikelet imbricated all round (subdistichous in n. 5).
[+] Achene crowned with the bulbous persistent base of the style (usually deciduous in n. 7); flowers without inner scales (bractlets).
[++] Hypogynous bristles (perianth) generally present; culm naked.
4. Eleocharis. Spikelets solitary, terminating the culm. Stamens 3.