384 CRUCIFER^ 



Inflorescence, Flower and Fruit. — The inflorescence is 

 a long raceme, the flowers small, about ^ an inch across, 

 with narrow spreading sepals and pale, yellow petals. The fruit 

 is a hisped silique, about ij or 2 inches long, with a long, 

 slightly curved sword-shaped beak; the valves of the silique 

 have three nerves. 



When ripe the siliques and seeds are of pale colour, hence 

 the name white mustard in contrast to the black species with 

 dark-coloured siliques and seeds. 



Its leaves and siliques at once distinguish it from the other 

 species of Brassica mentioned. 



For sheep-feed it is usually sown broadcast any time from 

 April to August, at the rate of 20 lbs. of seed per acre. Its 

 chief merit is its very rapid growth, which makes it of service for 

 catch-cropping after vetches, potatoes, and other similar crops, 

 or where turnips have failed and the time for sowing a more 

 useful crop has past. It is ready for folding with sheep from six 

 to eight weeks after the seed is sown. For use as 'green 

 manure ' it is generally sown in July or August ana ploughed in 

 during October and November. 



Composition. — The green plant in full bloom contains on an 

 average about 83 per cent, of water, i\ per cent, of carbohydrates, 

 2 per cent, albuminoids, and 6 per cent fibre. 



The seeds contain 26^ per cent, of a fixed oil similar to that 

 in other cruciferous seeds ; when extracted it is used for mixing 

 with rape oil. 



The seeds of white mustard when ground and stirred with 

 cold water, have not the odour so characteristic of the black 

 species; nevertheless the pungent taste is very similar in both 

 species. 



A glucoside, which is named sinalbin, is present in the seeds 

 of white mustard, and also myrosin. When water is added to 

 both, the myrosin decomposes the sinalbin into sugar, an acid 

 salt of sinapin, and sinalbin mustard oil (CyHjO'NCS). 



