SOME IMPORTANT FAMILIES OF ANGIOSPERMS 305 



have false fruits in whose formation the calyx takes part ; to 

 this division belong the quince, pear, apple, and crab-apple, 

 the thorn-apple or hawthorn, the mountain ash, and the 

 service berry. Another division includes the strawberry, 

 the cinquefoil, and the avens ; to another belong the 

 brambles, the raspberry, blackberry, and some related plants 

 with edible fruits ; another includes the many species and 

 varieties of roses ; and to still another division, whose mem- 

 bers have stone fruits, belong the cherry, plum, apricot, 

 peach, and almond. The almond, as we buy it, corresponds 

 to the stone of a plum or a peach ; the outer layer of the fruit, 

 corresponding to the fleshy part of a peach, has dried and 

 split off. 



317. The Pulse Family. With one exception, this, with 

 over 12,000 species, is the largest family of seed plants. 

 The bean may be taken as a type. Most of the members 

 have flowers and fruits constructed much like those of the 

 bean, although not a few have regular or nearly regular 

 flowers. Some of the more important plants of the pulse 

 family were mentioned in Chapter XII. 



318. The Flax Family. This is very small, and is men- 

 tioned here only because of one important member, the flax 

 plant. Flax has been cultivated for its strong bast fibers, 

 which are used in making linen thread, in the countries about 

 the eastern end of the Mediterranean for four or five thousand 

 years. It is now raised chiefly in Europe, the United States, 

 and India, both for the fibers and for linseed oil, which is 

 made from its seeds. 



319. The Rue Family. This family is of practical interest 

 because of one tropical and subtropical genus (Citrus}, to 

 which belong the orange, lemon, citron, and lime, all of 

 which probably originated in southern Asia, and the grarje- 

 fruit, a native of the Malayan and Polynesian islands. 



320. The Spurge Family. This is a large family, whose 

 flowers, usually clustered, vary greatly in structure. Most 



