POLYCARPICJE. 



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projecting thorny ribs on the lower surface. In the intercellular 

 passages of the leaves are some peculiar, stellate cells. 



Nuphar has 5 sepals, and an hi/pogynous flower. The petals, which 

 are small, have a nectary on the back; the coloured inner side of the sepals 

 functions as petals ; the ovate gynoeceum is quite free. N. luteum is a native 

 plant (Yellow Water-Lily), with, most frequently, 13 petals and 10-16 locitli in 

 the ovary. The rhizome is horizontal, as much as 5-6 cm. in thickness, and 

 bears on its under surface a number of roots, which on dying-off leave deep 

 scars ; the leaves are borne in spiral lines, and the flowers are solitary in 

 certain leaf-axils. The construction of the rhizome is very peculiar ; the 

 vascular bundles are scattered and closed as in a monocotyledonous stem. 



A P, C 



FIG. 383. Nympliaia: A flower in longitudinal section, the most external leaves being 

 removed ; B fruit ; C seed of Nuphar (longitudinal section) ; the perisperui at the. base, 

 the endosperm at the top surrounding the embryo. 



Nymphaea has 4 sepals, and the flower is more or less cpif/y- 

 nons. Petals and stamens are inserted at different heights on the 

 ovary to just beneath the stigma (Fig. 383). Nymphxa alba (White 

 Water-Lily). Victoria regia from the Amazon, and Enryale ferox 

 from Asia, have entirely epigynous flowers. The shield-like leaves of 

 Victoria areas much as 2 metres in diameter, and the edge is bent up to a 

 height of 5-14 cm. ; the flowers are 20-40 cm. in diameter, and change in 

 twenty-four hours from white to rose-red. A development of heat, as much as 

 14C. above the temperature of the air, together with a strong formation of 

 carbonic acid, has been observed during flowering. 



POLLINATION. Nymph<ea alba and other species of the sub-genus Kt/mpJii/- 

 topleura are self-pollinated ; the sub-genus Leptopleura is insect-pollinated. 

 NitpJutr and Victoria can effect self-fertilisation ; Enryale is self-fertilised, often 

 in entirely closed and submerged flowers. The dissemination of the seeds in 

 Nnphar luteum is effected by the fruit, which rests on the water, becoming de- 



