Habit: herb

Important diagnostics: aquatic plants

Taxon group: dicots

Leaf: blade: margin: dentate

Flowers: inflorescence: solitary

Flowers: disc: present

Flowers: sepal number/calyx lobes: 4

Flowers: petal number/corolla lobes: 4

Stamen: number: 4

Pistil: style: style 1, or styles more or less connate

Pistil: ovary: 2-loculed

Pistil: ovule: 1 per locule

Pistil: pistil: ovules attached to the apex of the ovary

Ovary: position: half-inferior

Stigma: 2-cleft

Fruit: types and characters: a nut (incl. achene, caryopsis, schizocarp, pyrene, etc.), spiny

Seed: endosperm: seeds without endosperm

Google Image Search: Link

Dictionary of The Families & Genera of Chinese Seed Plants: Link

Vascular Plant Type Catalog at NYBG: Link