GENERA AND SPECIES. 
Fruitlets 4; branches leafy; sepals 2; petals 2, 
small, bract-like. Aquatic plants, leaves usually 
stipulate ‘ ae ‘ 
Sepals present, 3, bract-like ; flowers bisexual. — 
Fruitlet one; branches leafy, flowers in spikes. 
Maritime Be ins age é 
Sepals absent ; flowers in spikes. 
Fruitlets usually 4; flowers bisexual, spikes on 
long spiral filiform stalks; stamens 2. Aquatic. 
Fruitlet solitary. Flowers of both sexes in 2 
alternate rows, enclosed in the sheathing base of 
floral leaves ; stamen of one anther ; stigmas 2. 
Maritime = Fee 
11. Flowers solitary, scattered, unisexual within 
sheathing bracts. 
Fruitlets 3, stalked; stamens 3, anthers connate ; 
stigma 1; leaves capillary, alternate. Calyx 3- 
lobed. Aquatic sak de; ie aa 
Fruitlets 2; style bifid; anthers 2, sessile, connate, 4- 
celled; flowers concealed by the clasping appressed 
leaf-sheaths ; leaves alternate. Maritime... 
Fruit simple, often connate with the small tubular 
calyx; leaves opposite, narrow; stigmas 2 to 4. 
Aquatic ... ore inl ah: 
Triglochin. 
1. Fertile fruitlets 3, separating when ripe from 
a central axis. 
Dwarf tufted terrestrial annuals; leaves filiform. 
Fruitlets linear, 3-ribbed, bidenticulate at the base; 
lower flowers often with 3 sepals and 1] stamen 
only, terminal flower with 6 stamens 
Fruitlets broadly ovoid and terminated by the 
spreading style; lower flowers mostly with 1 
stamen only, terminal flower with 3 stamens 
Semiaquatic, somewhat tall and slender, stoloniferous ; 
leaves filiform; flowers generally numerous, with 
3 stamens; fruits orbicular, compressed, dorsally 
streaked ... ‘ saa 
1. Fertile fruitlets usually 6, orbicular to narrow- 
oblong, often twisted; no central axis. 
Aquatic; leaves broadly linear, very long, 
upper part floating ... ‘* he 3 
175 
Potamogeton 
Posidonia 
Ruppia 
Zostera 
Lepilaena 
Cymodocea 
Naias 
centrocarpa 
mucronata 
striata 
procera 
