Ceratophyllum L.

1. Ceratophyllum L. View in CoL 2

Submerged aquatics, perennating by dormant terminal buds. Leaves in whorls of 3-8, dichotomously divided. Flowersaxillary, sessile, the male and female at different nodes. Perianth green in female flowers, whitish in male. Stamens c. 15. Nut usually spiny.

The species are distinguished principally by the fruit; since flowers are produced rather rarely many records are open to doubt.

All species inhabit still or slow-moving waters.

1 Nut without basal spines 2. submersum 1 Nut with two conspicuous basal spines at least 2 mm long

2 Nut muricate with small spines on the lateral faces

4. muricatum 2 Nutwithsmoothfaces;spinesarisingonlyfrommarginsor apex

3 Terminal spine of nut 5-9 mm; leaves forked once or twice

1. demersum 3 Terminal spine of nut less than 2- 5 mm (sometimes absent); leaves forked 3-5 times 3. tanaiticum