104 NYMPHLEACE.<E. 



and rind. Arillus wanting. Seeds smooth, and with the 

 albumen, embryo, &c, of essentially the same conformation 

 as in Nymphsea. Cotyledons parallel with the raphe, or 

 rarely at right angles to it. 



Herbs, growing in quiet or stagnant water ; the floating 

 or frequently emersed and erect leaves cordate, sagittate, or 

 reniform, thickish, entire, involute in vernation, fixed at the 

 sinus to the long and stout petioles, which with the one- 

 flowered peduncles spring from a prostrate rhizoma, as in 

 Nympluea. Flowers dull yellow, not showy. 



Etymology. A name used by Dioscorides, said to be of Arabic origin. 



Geographical Distribution. Natives of the cooler parts of the north- 

 ern hemisphere : a genus of five or six species, of whieh there are three in 

 the United States. 



PLATE 44. Nlthar advena, Ait. (From spontaneous specimens.) 



1. A flower-bud, of the natural size. 



2. An expanded flower ; natural size. 



3. Diagram of the eestivation of the sepals (in two series). 



4. Vertical section of an unexpanded flower ; natural size. 



5. Enlarged petal, outside view ; and 6, lateral view of the same. 



7. A stamen, enlarged, seen from the inside. 



8. Same, as seen from the outside ; and 9, seen laterally. 



10. Half of a transverse section of an ovary, moderately magnified. 



11. An ovule, more magnified. 



12. Fruit, of the natural size, with remains of stamens, &c, at the base. 



13. Vertical section of a fruit with the receptacle, dividing one of the cells. 



14. A pulpy cell or carpel, detached entire from the adjacent side of fig. 13. 



15. A seed, enlarged. 



16. Vertical section of the hilar end of a seed, magnified, cutting through 



the fleshy sac, removing one cotyledon, and showing the plumule. 



17. The sac removed entire ; enlarged. 



18. Same, cut through, showing the embryo (edgewise) entire. 



19. Embryo, more magnified, the cotyledons opened to show the plumule. 



