218 NYMPH AKACKAF 



This is the only species of water-lily [plotnb] within 

 our limits'. It inhabits permanent vleis, ponds and calm 

 pools along rivers, bearing sweet scented, mostly blue, but 

 occasionally purple flowers. They open only in sunshine, 

 closing again at night and re-opening next morning when 

 the sun is fairly high. This movement is effected by the 

 sepals, for ii these be cut away when spread out, the 

 flowers cannot close again. They do not float on the 

 surface of the water like those of the European water- lil\ 

 [IV. a3a)y but stand upright about a foot above the surface. 

 Pedicels and peduncles are traversed by spacious air- 

 channels, and the tissue contains numerous stellate sclerotic 

 cells, which are a means of defence against snails like the 

 raphides of the sorrels. After flowering, owing to the escape 

 of some of the air in its cavities, the receptacle becomes 

 submerged, and the fruit develops underneath the water. 

 When ripe the walls of the fruit decay, and the pseudo- 

 capsule breaks up, thus liberating the seeds. As each seed 

 is enclosed in the inflated, membranous arillus, it floats 

 on the water and is carried about until the air escapes, 

 finally sinking to the bottom. If the water be not too 

 deep, the seed germinates at once, producing at first only 

 linear leaves without a blade. In very shallow water even 

 the first leaves develop a floating blade. (Fig. 95, 1.) 



The only S. A. genus (2 species in S. A.). Nymphaea /.. 



Fam. 25. Ceratophyllaceae. 

 Submerged aquatic herbs. Leaves in whorls, 

 simply or repeatedly furcate. Flowers in the axils of 

 the leaves, whitish, monoecious; $ flowers with about 12 

 segments and 12-16 stamens, the anthers with a 2 -pointed 

 connective, v flowers with 9 10 segments. Carpel 1, 

 1 -celled, i-ovuled; style long, subulate; ovule orthotropous 

 with 1 integument. Fruit a nut. Seed with a thin 

 endosperm and 2 large cotyledons. 



The on!)' genus (3 species, 1 extending to S. A.). Ceratophyllum /.. 

 * Wood & Evans, Natal Plants, Vol. 1, t. 53, is apparent!) .V. madagascariensis. 



