NYMPHS ACE.E 115 



Brasenia, Euryale, and one to two in each carpel or nut of 

 Nelumbium. The ripe seeds are often covered with a pulpy or 

 fleshy aril, which in Euryale is large and fleshy, and serves to 

 float the seeds after liberation from the spongy, baccate fruit, 

 until it bursts or gets broken, when the seeds immediately sink. 



The embryo of Cabomba differs from that of Nuphar or 

 Victoria in being shortened, flattened, and rhomboid in vertical 

 section with a scarcely discernible caulicle connecting the coty- 

 ledons. 



The seeds of Nelumbium differ from all others of the Order 

 in being exalbuminous. The seed contains an embryo con- 

 sisting of two large, hemispherical, fleshy cotyledons connected 

 by the caulicle or primary axis. Between these is a strongly 

 developed plumule, the leaves of which are closely longitudin- 

 ally involute at the margins. The petiole is also bent back- 

 wards in the direction of the radicle. Germination is very 

 rapid after access of water to the embryo and takes place in a 

 very few days if a small hole is artificially made in the woody 

 pericarp. 



Cotyledons. The typical cotyledons of this Order as far as 

 observed are subterranean that is, remain in the seed even 

 after germination. Nymphsea, Victoria, and Euryale may 

 be given as examples. Another type is seen in Nelumbium, 

 which, alone in the Order, has exalbuminous seeds. These are 

 larger than any other of the Nymphaeaceae, and contained in 

 a thick and lignified pericarp, while the embryo occupies the 

 whole of the interior, to which it conforms. The cotyledons are 

 hemispherical and lodge between them the greatly enlarged or 

 advanced plumule. They are also subterranean during ger- 

 mination, serving merely as a storehouse of reserve-material. 



Leaves. The leaves of most species of the Order are 

 floating and exhibit but a few types. Seedlings are generally 

 heterophyllous, a circumstance of frequent occurrence amongst 

 aquatic plants whether phanerogams or cryptogams. In the 

 adult state of the plants, all of which are aquatic or marsh- 

 loving herbs, four distinct types may be given, namely, those 

 which are oblong, orbicular, scutiforni, or subsagittate, repre- 

 sented by Nymphsea and Nuphar; secondly, peltate and floating 

 leaves, as seen in Brasenia, Victoria, and Euryale ; thirdly, 



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