Habit: herbs, often semi-aquatic, stems often triangular
Leaves: alternate or basal, 3-ranked, simple, entire, linear, basally sheathing, sheath closed, ligulate or eligulate, blades flat, terete, triangular, or absent.
Plants: synoecious, monoecious or dioecious.
Inflorescence: 1-many spikelets, secondarily aggregated into panicles, etc.
Flowers: perfect or imperfect (dioecious or monoeceous), subtended by bractlets, regular or naked
Perianth: reduced to bristles (rarely scales) or absent
Ovary: 2-3 syncarpellate, ovary superior, 1 locule, 1 basal ovule, style 1 with 2-3 branches