444 



SYSTEMATIC BOTANY. 



leaves. Sepals and petals 3 or 4, alternating with each other. 

 Stamens definite or niimerous. Thalamus flattened, small. Car- 

 pels 2 or more, distinct. i^rwiYindehiscent. Seeds few; embryo 

 minute, enclosed in a vitellus, and outside of abundant fleshy 

 albumen. 



Diagnosis. — The only orders likely to be confounded with this, 

 are the Nymph£eacese, and Nelumbiacese. The plants belonging 

 to the Cabombacece are distinguished from the Nymphseacese, 

 by having distinct carpels, sutural placenta, few seeds, no evident 

 thalamus, and by the presence of fleshy instead of farinaceous 

 albumen ; and from the Nelumbiacese, by their small thalamus, 

 by having more than one seed in each carpel, by their minute 

 erpbryo, and abundant albumen. 



Distribution, ^c. — There are only 2 genera, and 3 species 

 belonging to this order. They occur in America, Australia, and 

 India. Examples : — Cabomba, Hydropeltis. 



Properties. — They have no important properties. Hydropeltis 

 purpurea is said to be nutritious. 



Natural Order 10. Nymph.^ace^. — The Water- Lily Order 

 (figs. 850 — 852). — General Character. — Aquatic herbs. 



Fig. 850. 



Fig. 851. Fig. 852. 



Fig. 8.'>0 Flower of Yellow Water-Lily {ytiphar lutea) Fig. 8.51. Ovary 



of Nvj)har with numerous radiating stigmas Fig. 852. Vertical section of 



the seed of Kymiiltmi alba, showing the embryo euclosed in a viteUus, and on 

 the outside of albumen. 



Leaves floating, peltate or cordate. Flowers solitary, large and 

 showy. Sepals usually 4 (fig. 438, c, c, c, c), persistent, generally 

 petaloid on their inside. Petals numerous (fig. 438, p), deciduous, 

 often passing by gradual transition into the stamens (fig. 438, p, 

 1, 2), in the same way as the sepals pass into the petals ; inserted 

 on a fleshy thalamus below the stamens (fig 509). Stamens 

 numerous, placed upon the thalamus; filaments petaloid (figs. 

 438, e, 1, 2, 3, 4, 5, and 850). Thalamus large, and forming a 

 disk-like expansion, more or less surrounding the ovary, and 



