28 :©otan« 



« 



each ring start fibrous roots. The lower end of the 

 stem looks as if it had been bitten short ofT by some 

 animal. Every ring on this buried stem marks a 

 year of the plant's life ; thus nature keeps some of 

 her chronicles. We Avill mention but one other 

 underground stem, that of the potato. 



The potato has three kinds of stems. First, green 

 stems which bear leaves ; second, green stems which 

 bear flowers and seeds only ; third, underground 

 stems which are the fleshy tubers that we eat. The 

 chief part of the food stuff of the potato plant is 

 carried down the leaf stem into these thickened 

 underground branches, and there stored up, chiefly 

 in the form of starch. The great supply of a very 

 nourishing food stuff whi(^h the potato is able to la}'' 

 up, has made it a valuable article of diet for man. 

 The care of the farmer lias been directed to increas- 

 ing this tendency of the potato to store up food. 

 The potato comes from the uplands of the Andes of 

 Chili, and since its discovery, in 1563, it has been 

 cultivated in almost every country cool enough for 

 its growth. 



A remarkable form of stem is shown in the cactus 

 family. These plants grow in hot, sandy countries, 

 subject to long droughts. The amount of food and 

 moisture which they are enabled to la}^ up in their 

 stems fits them well for their habitation. These 



