^ Per. o or simple and hypogynous {or, if 
double, not coloured). Carp, nearly or 
quite free. 
Family 2. POTAMOGETONACEiE.^ Submerged 
or floating. Lea. 2-ranked, with sheathing base. 
Flow, inconspicuous, solitary or spicate, ^ or 
i-sexual. Per. of 4 small segments or o. Sta. i — ^4. 
Carp. I — ^4 (rarely more), each with i pendulous 
orthotropous ovule. Fr. a drupel or achene. Seeds 
exendospermous. 
Potamogeton, Ruppia, Zannichellia, Zostera 
Family 3. NAIADACE^.* Submerged. Stem 
with central bundle. Lea. opposite, linear. Flow, 
i-sexual; of 2 cup-shaped envelopes and i ter- 
minal anther; 9 of i cup-shaped envelope or o, 
with I carp, containing i basal anatropous ovule. 
Fr. a drupe. Seeds exendospermous. Naias. 
[Aponogetonace.^.* Lea. submerged or floating. 
Flow, g , spicate, enclosed in a deciduous spathe. 
Per. I — 3, petaloid. Sta. 6 or more. Carp. 3 — 6, 
with 3 — 6 styles; each carp, with 2 — 00 erect 
anatropous ovules. Aponogeton (inch Ouvirandra) .'j 
Family 4. JUNCAGINACE^.* Marsh herbs, 
with narrow lea. Inflor. a racemose scape. Flow, 
small, greenish, actinomorphic, ^ or i-sexual. Per. 
6, herbaceous, in 2 similar whorls. Sta. 6. Carp. 6 
or 3, each with i or 2 basal anatropous ovules. Fr. 
schizocarpous or of follicles. Seeds exendosper- 
mous. Triglochin, Scheuchzeria. 
* These four families are considered by Bentham and 
Hooker to form one family, Naiadeae. 
4 
