SECT, ir 



PHANEROGAMIA 



687 



runners ; tliey pass the winter at the bottom of the water, in some cases as special 

 winter buds (cf. p, 277), and grow up again in the spring. Flowers dioecious ; 

 perianth differentiated into calyx and corolla. The male floAver has several 

 trimerous whorls of stamens ; the female flower possesses staminodes and two 

 trimerous whorls of carpels. Ovary inferior. Entomophilous. Vallisneria spircdis 



Fig. 7i3.—Potamogeton natans. Flowering shoot. (J nat. size.) 



(cf. p. 495), a fresh - water plant of the tropics extending to the Italian lakes. 

 Elodea canadensis, the Canadian water- weed. 



Ordep 2. Glumiflorae 



This order consists entirely of annual or perennial plants of grass- 

 like habit. A woody stem only appears in the genus Bamhusa. The 

 association in more or less complex inflorescences of numerous flowers, 

 which lack a proper perianth but are enclosed by scaly bracts (glumes), 

 is a common character of the order. The perianth is either completely 

 wanting or reduced to a series of scales or bristles. The inner whorl 

 of stamens is also usually wanting, The superior ovary is always 



