366 CRUCIFER^ 



frequently effect cross-fertilisation when searching tor honey. Self- 

 fertilisation is however common, and productive of good seed. 



The Order comprises about 1200 species, mostly of herbaceous 

 or slightly shrubby character ; practically all are non-poisonous 

 and extensively represented in temperate and cold regions. 



The inflorescences are usually simple racemes without bracts 

 or bracteoles. 



Many plants belonging to the Cruciferse, such as cabbage, kohl- 

 rabi, turnip, swede, rape, and white mustard, are very valuable 

 to the farmer. 



Acrid, pungent compounds are present in various parts of 

 mustard, charlock, radish, and many other cruciferous plants. 



Instead of starch being stored as reserve food-material for 

 the young plants, the tissues of the embryos of nearly all the 

 Cruciferae contain considerable quantities of oil. 



The seeds of several species belonging to the genus Brassica 

 furnish oil which is sold under the name of Colza oil or Rape oil. 



A number of plants, such as charlock, wild radish, shepherd's- 

 purse, Jack-by-the-hedge, and hedge mustard, belonging to the 

 order are common weeds of the farm, while others, such as 

 the wallflower, stock, and candy-tuft, are ornamental plants 

 of the garden. 



So far as the farmer is concerned, the most important genus 

 of the Cruciferae is the genus Brassica, which includes the turnip, 

 swede, rape, and the cabbage and its varieties : some botanists 

 include black mustard, white mustard, and charlock in it, while 

 others place these plants in a separate genus, Sinapis : the 

 former plan is adopted here. 



2. Wild Cabbage {Brassica oleracea L.). — This plant, which is 

 the parent of all the cultivated forms, grows on the sea cliffs in 

 the south of England and various parts of northern Europe. 

 It is a biennial, or perennial with a stout erect stem from i to 2 

 feet high. The lower large, broad leaves, are obovate with 

 lobed margins, smooth, and of ashy green hue. The upper 



