1638 A TEXTBOOK OF THEORETICAL BOTANY 



Fig. 1499. — Co}'ydaUs liitea. Longitudinal section of flower 

 to illustrate the description of pollination in the text. 



result that, in young flowers, their under surface is dusted with pollen, 

 which has been shed on to the stigma, and transfer it to the stigmas of older 

 flowers which have already lost their pollen. When the weight of the insect 

 is removed the hood springs up by its elasticity and again covers the stigma. 

 The pollination mechanism in Fumaria (Fig. 1500) is essentially similar to 



Fig. 1500. — Futnaria sp. Longitudinal section of flower 

 to illustrate pollination. See in text. 



that in Corydalis, but the flowers are usually smaller and owing to their late 

 flowering it seems likely that self-pollination is more common. This is 

 emphasized by the fact that viable seed is often set in very wet weather. 



Cruciferae (Brassicaceae) 



Included in this family are a large number of important vegetable crops 

 as well as many well-known garden and wild flowers. Probably the most 

 important is the wild Cabbage, Brassica oleracea, from which all the 

 vegetables known as "Greens" have been developed. Among these we 

 may mention the Cabbage, Brussels Sprout, Cauliflower, Broccoli, Kohl- 

 rabi, Kale or Borecole and Savoy, all of which are varieties derived from 

 the above species. Other species of the same genus have also contributed 

 to the vegetable crops: Brassica rapa has given rise to the Turnip and B. 



