io6 THE STORY OF PLANT LIFE 



the bottom is gravelly, and is extremely local. Its 

 associates are Water Lobelia, Bladderwort, Lake- 

 weed, and, amongst others with floating leaves, Quill- 

 wort and Pillwort. 



The habit is the rosette habit, and the plant grows 

 under water. The roots have long white fibres, 

 densely tufted and matted, the root-stock being small. 

 The leaves are cellular, radical, slender, lance- 

 shaped, pinnatifid, or entire, in clusters of one to three, 

 long, round in section, and awl-like (hence Stibu- 

 laria). The plant is quite smooth. 



The flowers are few, white, borne on a naked scape 

 I to 3 in. long. Ten of them placed side by side 

 would measure but an inch across. The petals are 

 extremely minute. The stalks are short and ascend- 

 ing. The sepals are equal and spreading. The 

 stigma is stalkless and entire. The pods are small, 

 oblong, or globular, shortly stalked, the valves ribbed 

 and convex. The septum is membranous. The 

 seeds are few, five to six in each cell, in two rows. 

 This plant differs from Draba in having the radicle 

 or root portion of the embryo incumbent on the back 

 of the linear cotyledons. It bends above their base, 

 as in Wart Cress, not where they meet the radicle. 

 The seeds are pale-brown and dotted. 



The flowers are in bloom in July and August. The 

 plant is a herbaceous perennial, and is not more than 

 3 in. high. 



Sometimes the flowers, on the rather long aerial 

 scapes, project above water, in which case they may 



