332 ESSENTIALS OF BOTANY 



The Gourd family furnishes many edible fruits. Of these 

 the pumpkin and the summer squashes are varieties of 

 the same species, and the large winter squashes belong to 

 another species of the genus Cucurhita, probably of Amer- 

 ican origin. The watermelon belongs to a genus (Citrul- 

 lus) of Asiatic origin. The muskmelons, nutmeg-melons 

 and other varieties, and the cucumber belong to another 

 genus (Ciioumis), and most of our varieties are descended 

 from two southern Asiatic species. 



408. Edible Leaves, Stems, and Roots. — Not many 

 kinds of food of prime importance consist of the leaves 

 or aerial stems of plants. The Lily family yields aspar- 

 agus ; the Pigweed family, spinach ; the Mustard family, 

 water-cress, cabbage, cauliflower, and Brussels sprouts; 

 the Parsley famil}'', celery ; and the Compositce, lettuce and 

 globe artichokes (^Cynara). 



Since the underground portions of the plant often store 

 up much reserve material (Sect. 76), it is evident that 

 bulbs, rootstocks, tubers, and roots must often be of 

 value as food. Only a few of the most important of these 

 are here mentioned. The Lily family yields onions; the 

 Yam family, yams ; the Pigweed family, beets ; the JMus- 

 tard family, turnips and radishes ; the Parsley family, 

 carrots and parsnips ; the Morning-glory family, sweet 

 potatoes; the Nightshade family, potatoes; and the Coin- 

 positcB, salsify and Jerusalem artichokes {Helianthus). 



The potato crop is so important that a few words maj- 

 here be said about it. The annual yield for the L'nited 

 States is usually over 200,000,000 bushels. Introduced 

 into cultivation from Peru, potatoes soon became one of 

 the principal foods of the cooler parts of the world. They 

 are particularly well suited for cultivation in regions where 



