1. Saltwater species...16

1. Plants in fresh water (rarely brackish water); fruits not inflated (but see semifleshy ripe fruits in Cladium); leaves usually restricted to top or base of plant, or absent, or sometimes cauline...2

2. Achenes with a bonelike white covering;  plants with a tuft of bracts at the top AND with spikelets in globose heads...

2. Achenes not with a white covering;  spikelets only rarely in globose heads (see also Cyperus difformis, C. croceus)...3

3. Plants leafless except for sheaths...4

3. Plants with leaves at the base or at the summit, or occasionally along the culm...5

4. Plants usually < 1 m tall; style base expanded into a bulb on the top of the achene; spikelet 1...

4. Culms usually > 1 m tall; style base not expanded or scarcely so; spikelets numerous...

5. Perianth parts (structures resembling sepals or petals) 6 and persistent around fruit; fruit opening into 3 segments; seeds numerous in each fruit...

5. Perianth absent or represented by bristles (or with 2-3 expanded lobes in Liopcarpha, Fuirena, and Scirpus); fruit an achene that does not open, and contains one seed...6

6. Flower and achene encased by leafy sheath or envelope (perigynium), this flat and waferlike... (Break open a dry spikelet and look for paper-thin wafers that flutter on the wind.)

6. Perigynium absent...7

7. Spikelets black (see also Rhynchospora nitens), in a tight cluster on the side of a "knitting needle" culm, the achene white with a black style base...

7. Plants otherwise...8

8. Large sedges > 2 m tall of Everglades and open marshes, leaf blades > 1 m long with severe serrate margins.  Inflorescences large plumose panicles. Fruits slightly fleshy when ripe... (Sawgrass)

8. Plants otherwise...9

9. Flowers with broadened perianth scales (resembling tiny paddle-shaped petals)...10  (Perianth = sepals, sepals, or organs resembling these.  Some sedges have bristles around their flowers/fruits, and in some the bristles are broadened resembling mini-petals.   For our purposes bristles or broadened bristles are called perianth parts.)

9. Flowers with no perianths, or the perianth limited to bristles...11

10. Flowers with broadened perianth parts AND with bristles; spikelets mostly > mm long...

10. Flowers with 2 broadened perianth parts but no bristles; spikelets usually < 8 mm long...

11. Plants with leaves along the stem; fruits glossy white (or gray), glossy and conspicuous...

11. Plants usually with leaves confined to the base and/or top, or absent; fruits usually brown or black...12

12. Achene with a beak or tubercle on the summit (may be difficult to see in Fimbristylis but this with the style having a broad base, fringed beneath the stigmas,  and with no perianth bristles)...13

12. Achene with no beak at the summit (see note on Fimbristylis above)...14

13. Perianth bristles usually present (rarely absent); leaf sheath margin solid; styles usually 2 and the fruit usually flat (but may have 3 styles and triangular fruit)...

13. Perianth bristles absent; leaf sheath delicate, torn, and fringed; fruit triangular and styles 3...

14. Beach plants < 20 cm tall...

14. Plants not on the beach (or rarely so but then > 15 cm tall)...15

15.  Spikelet scales 1-3; plants under 25 cm tall... (often weeds in turf and in low vegetation of moist disturbed areas)

15. Spikelet scales 5 or more; plants often (not always) > 25 cm tall... (Usually but not always with a whorl of bracts at the summit of the plant)

16. Low (10-25 cm) sedge on dunes... (Rachis corky)

16. Plants > 25 cm tall...17

17. Spikelets 1-25 in number, 10-30 mm long, 6-10 mm in diameter...

17  Spikelets 10-60 in number, 6-22 mm long, 2-4 mm in diameter ... (Similar to .  See these species)