400 FIELD CROPS 



was probably introduced into the United States during the 

 colonization period by early Spanish settlers. 



643. Botanical Characters. The potato is a fibrous- 

 rooted plant which is perennial by means of the tubers it 

 produces. It is for these tubers that it is grown, and by 

 means of them it is propagated. As the tubers will not 

 stand freezing, they are stored over winter, and thus the 

 potato is grown as an annual. The plants grow from 2 to 4 

 or 5 feet long: the stems are smooth and somewhat angular. 

 When the plant reaches its maximum length it is usually re- 

 cumbent, with the leaves and branches stretching up from 1 

 to 3 feet. The compound leaves vary with the different va- 

 rieties and stages of growth. The leaflets are generally ovate. 



The white or purple flowers appear in terminal clusters. 

 They are about 1 inch in diameter, with a five-parted, bell- 

 shaped corolla. Each flower has five stamens and a two- 

 celled pistil which occasionally matures seed. When seed is 

 matured, it is often unhke the parent plant, because the 

 flowers are cross-fertiHzed. Most of the new varieties of 

 potatoes are obtained by planting this seed and making selec- 

 tions from a large number of seedlings, most of which are 

 practically useless. Potatoes are most universally repro- 

 duced from tubers, and when one ordinarily speaks of seed 

 potatoes he has reference to the tubers and not to the true 

 seed. Numerous sUght indentations, or ''eyes," are to be 

 found on the surface of the tubers. These are most numerous 

 at the "seed" end, while there are comparatively few at 

 the "stem" end where the tuber was attached to the parent 

 plant. It is from the buds in these eyes that new plants are 

 produced when the tubers or portions of them are planted. 



There are about nine hundred species of the genus 

 Solanum, but only a few are cultivated plants. The tomato 

 and nightshade belong to this genus, and tobacco belongs to 

 the same family. Potatoes and tomatoes are so closely re- 

 lated that the branches of one may be grafted upon the other. 



