132 THE BOOK OF NATURE STUDY 



Cabbage Sprouts Ellams Early, Enfield Market, Daniel's 



Defiance. 

 Savoy Sprouts Drumhead, Perfection. 



THE POTATO (Solanum tuberosum) 



This vegetable is indigenous in Chili, where it grows in the 

 wild state at considerable heights above the sea level. For 

 this reason, probably, the cultivated Potato is found to thrive 

 on the uplands in this country. The Spaniards introduced it 

 into North America from Chili, and Sir Walter Raleigh brought 

 it to England late in the sixteenth century. The Potato plant 

 possesses a green herbaceous aerial stem, and a short rhizome 

 with closely clustered tuberous branches which constitute the 

 edible part. On the tubers are depressions arranged spirally, 

 called the " eyes," and in the " eyes " are a number of buds. 

 As in the case of an aerial stem, the " eyes " are more numerous 

 at the apex of the tuber. The tubers if exposed to light develop 

 chlorophyll and turn green. The tubers are classified by the 

 growers into three divisions, namely : the round, the oval, and 

 the kidney shape. The tubers contain from 18 to 20 per cent, 

 of starch, and it is on the proportion of this substance that 

 their value for food depends. Other things being equal, the best 

 Potatoes are those containing abundance of starch grains packed 

 in large cells with thin cell walls. 



The fruit of the Potato plant is a berry containing numerous 

 seeds. New varieties are obtained by sowing the seeds produced 

 by cross fertilisation and propagating the tubers for four years, 

 when they are large enough for their value for food purposes 

 to be determined. The tubers of the first year are only about 

 as large as peas. Potatoes are grown in immense quantities in 

 Ayrshire and in Lincolnshire. The total annual production in 

 the United Kingdom is about eight million tons. 



The Potato is propagated by means of the tubers. Now, the 

 tuber is a part of the stem, and hence, since the life of a plant 

 is limited, it follows that propagation by this method cannot 

 be continued for an indefinite period. It follows from this that 

 any given variety must after a time die out, and as a matter of 



