102 NYMPH^EACEjE. 



branaceous cellular arillus, which is open at the extremity : 

 testa crustaceous, marked with a narrow raphe ; the inner 

 integument membranaceous. Albumen farinaceous, perforat- 

 ed with a central canal leading to the membranaceous clos- 

 ed sac, immersed in a depression at its hilar extremity, 

 which is filled by the globular embryo. Radicle very mi- 

 nute, next the hilum : cotyledons fleshy, rounded, excavat- 

 ed internally to contain the two-lobed plumule. 



Herbs, growing in quiet water, with rounded peltate 

 leaves and solitary showy (white, purple or blue) flowers, 

 raised to the surface on long petioles and peduncles, which 

 spring from a fleshy prostrate lactescent rootstock. Verna- 

 tion involute. Blossom closing in the afternoon, usually- 

 sweet-scented. Fruit ripening under water. 



Etymology. Niyjc^nm, dedicated to the Water-Nymphs. 



Geographical Distribution. Natives of the northern temperate and 

 subtropical regions. Our single United States species is one of the finest of 

 these beautiful plants. 



Note. The arillus in N. alba is pretty well figured by Schkuhr (1791). 



PLATE 42,43. Nymph^ea odorata, Ait. ; — flower-bud, flower, and a 

 small leaf; natural size. 



1. Diagram of the aestivation and position of the parts of the flower. 



2. An outer petal, natural size. 



3. An inner petal, showing the rudiment of an anther at its tip. 



4. 5. Exterior petaloid stamens, natural size ; inside view. 



6. An inner stamen, seen from within. 



7. Pistil, &c. ; the floral envelopes and all the stamens but one removed. 



8. Vertical, and 9, transverse section of the pistil ; magnified. 



10. An ovule, more magnified. 



1 1 . Fruit, covered with the scaly bases of the persistent petals ; nat. size. 

 13. Vertical section of the same, showing the seeds on the partitions. 



13. Magnified seed in the arillus ; and 14, with the arillus divided. 



15. Longitudinal section of a magnified seed, dividing the albumen, and the 



sac, and cutting away one cotyledon, so as to show the plumule. 



16. Transverse section of the base of a seed, cutting through the sac and 



embryo. (Shows that the cotyledons are parallel with the raphe.) 



17. Embryo, magnified ; the cotyledons opened, showing the plumule. 



