98 THE STORY OF PLANT LIFE 



it seems to be a casual plant. Watson regarded it 

 as a colonist in all cases. On waste ground the 

 Treacle Mustard is found with Pepperworts, Penny- 

 cress, and the ordinary waste ground plants. Another 

 habitat is gravelly banks and fields. 



The habit of the plant is erect. The stem is stiff, 

 or rigid, with sharp angles, or round in section, and 

 is somewhat hairy, the hairs being closely appressed 

 to the stem. The leaves are almost stalkless, long, 

 oblong, or are lance-shaped, narrow, tapering to the 

 base into a short stalk, and not auricled as in Sisym- 

 brium, entire or with few small teeth. The hairs are 

 two- to three- partite, and stellate — that is, radiating 

 from a centre. 



The flowers are small, yellow, about a quarter of 

 an inch across. The ultimate flower-stalks are two 

 or three times longer than the calyx, shorter than 

 the pods. The stigma is somewhat dilated at the 

 top, and blunt. The style is short. The pods or 

 siliquas are numerous, and borne on spreading stalks, 

 being about an inch long, and twice or three times as 

 long as the stalks, straight, with acute, strongly 

 keeled valves. The seeds are very small and 

 numerous, and nearly two-nerved. 



The flowers are somewhat scented and fairly con- 

 spicuous. The honey is protected by the erect sepals, 

 being secreted in honey-glands at the base of the 

 short stamens, the petals being closed in wet weather. 

 The anthers and stigma open about the same time, 

 and as the style is short and the stigma enlarged 



