472 BOTANY or CROP PLANTS 



is loosely cymose. The flowers vary in color from white to 

 deep blue. The same plant always bears flowers of the 

 same color. Yellow-flowered varieties are not found in 

 this species. The petals are large, conspicuous, wedge- 

 shaped, and about twice as long as the sepals. 



Pollination.^Studies of flax varieties indicate that there 

 is close-pollination. Individual flowers produce seed freely, 

 whether associated with other flowers or not. Examination 

 of flax flowers at the proper time shows anthers in close 

 proximity to the stigmas, and the latter covered with pollen. 



Mature Fruit. — The flax fruit (Fig. 21) is a round capsule 

 known commercially as the "seed ball." The seed ball is com- 

 posed of five fused carpels. The balls are divided into five 

 true cavities or locules by means of five true partitions (septi) 

 extending from the wall (pericarp) to the axis. Each locule 

 contains two seeds and is divided more or less incompletely 

 into two loculi by means of false septi. The seed balls are 

 3^ inch or more in diameter. When fully ripe, they are 

 easily separated into parts at the points where the carpels 

 are joined. 



Seeds. — The seeds vary in length from J^ to }4, inch. 

 They are lenticular, compressed, and slightly longer than 

 wide. They have a very smooth, polished surface and vary 

 in color from yellow to dark brown. Light brown is the 

 standard color. A mucilaginous material which quickly 

 becomes sticky (viscid) in hot water is found filling the 

 epidermal cells of the seed. It is this substance which gives 

 flax its medicinal value. The embryo is surrounded by a 

 thin layer of endosperm which, in the mature seed, contains 

 starch. 



Geographical. — Common flax is a native of Europe. It is now widely dis- 

 tributed over the world, being grown commercially in many countries. India 

 is a heavy producer of seed, and in Argentina it is grown extensively for oil. 



