90 The Waterlilies. 



the sepals and outer four petals remain and become stiff and turgid and 

 develop a good deal of additional chlorophyll. The fruits of N. tetragona 

 And/lava are small (2 to 2.5 cm. long), and the persistent carpellary styles 

 form only an insignificant crown around the top. In Eu-castalia the 

 stigma grows very little if any after anthesis, but is about half as wide as 

 the diameter of the spheroid fruit. But in Brachyceras and Lotos, where 

 the fruits become 8 to 12 cm. across, the stigma keeps pace with the 

 growth of the rest of the pistil, so that the fruit has much the same shape 

 as the ovary of the flower. 



The seeds of waterlilies offer marked characteristics which are often 

 of great systematic value. They were made an object of special study by 

 Weberbauer (1894), from whose valuable paper many of the following 

 details, especially regarding N. alba, are taken. Some important species, 

 however, e. g., N. tetragona and flava, did not come under his notice. 

 The largest seeds are those of Xanthantha and Anecphya, then N. tetra- 

 gona, followed by N. tuberosa, Candida, alba, and odorata ; those of Lotos 

 and Brachyceras are considerably smaller than the preceding; the smallest 

 are found in Hydrocallis. They vary in number inversely as the size. 

 N. flava may have only seven perfect seeds to a fruit, or one to three per 

 carpel ; N. tuberosa has sixty to seventy, while N. lotus, rubra, caerulea, 

 capensis, zanzibariensis, and amazonum have thousands. They are nearly 

 globular in N. flava, flavo-virens, elegans, and amazo?ium, and ellipsoid in 

 the rest. The micropylar end is always slightly pointed, and in Eu-castalia 

 and Chamaenymphaea the raphe forms a gentle swelling along one side. 

 In Castalia the color of the seed is usually greenish black, but brown is the 

 regular color in N. tuberosa. Dark brownish-olive tints are found in all 

 others that I have seen, except N. amazonum, which is reddish brown, 

 covered with silvery hairs. 



The micropyle and hilum lie near together at one end of the seed. 

 The character of the surface, whether smooth or ridged or hairy, can best 

 be discussed in describing the microscopic details of structure. 



The aril which is attached to the ripe seed is a bell-shaped outgrowth 

 of the funiculus. It is whitish and translucent, mucilaginous, and holds 

 between its two coats tiny air bubbles. It is much shorter than the seed in 

 N. tuberosa, a little longer than the seed in N. odorata (Fig. 41, a), lotus, 

 caerulea, capensis, zanzibariensis, and amazonum, but in these the seed is 

 visible at the open end of the aril. In N. alba (Weberbauer) and glad- 

 stoniana the seed is completely inclosed and hidden by the aril, while the 

 aril of N. flava is a large, wrinkled bag, big enough, if stretched out, to 



