15 



MODK OI- LIFE I\ rKUKNMALS. 



29. 



>ots. But 

 y ; so that 

 t" the root, 

 le ground, 

 more and 

 neath, and 

 dose to the 

 [)sed to the 

 r of its two 

 the youn;w 

 isture and 

 'mosj)here, 

 'e digested 

 iage while 

 wanted by 

 down into 



for next 



large and 



bter, which 



In it, in 

 ' products, 

 ails of its 

 n the next 

 it, a stem 

 ers abun- 

 uishment 

 so is the 



B to \i\Q 

 Is. So a 

 le spring, 

 [•ed up in 



in which 

 )t in the 



leaves and in the short stem or stalk. Those accordingly become thick and 

 nutritions in the (.'abhago, jiist as the root does in the Turnip, or the base^ 

 of the short stem alone in Kohlrabi, or even the 

 flower-stalks in the C'aulitlower ; all of which Ixdong 

 to the same fannly, and exhiiut mer(dy ditl'erent 

 wavs of accomplishing the same result. 



73. Perennials are plants which live on year after 

 year. Shrubs and trees are of course perennial. So 

 are nmny herbs; but in the.se only a portion goncr- 

 allv survives. Most of our perennial herbs die down 

 to the ground l)efoi-e winter; in many species all but 

 ceitain se})arate jiortions under ground die at the 

 close of the year ; but some parts of the stem con- 

 taining buds are always kept alive to renew the 

 growth for the next season. And a stock of nour- 

 ishment to begin the new growth with is also pro- 

 vided. Sometimes this sto(;k is laid up in the roots, 

 as for instance in the Peony, the Dahlia (Fig. 58), 

 and the Sweet Potato. Here some thick roots, filled 



58 

 Dahllu roots. 



with food made by last j'ear's vegetation, nourish irv 

 spiing the buds on the Ijiise of the stem just above 

 {<!,'(), enabling them to send up stout leafy stems, 

 and send down new roots, ia some of which a new 

 stock of food is laid up during summer for the next 

 spring, while the exhausted old ones die ofT ; and so 

 on, from year to }ear. 



74. Sometimes this sto(k of food is laid iip in par- 

 ticular portions of branches-, 

 '>f the stem itself, formed 

 under groiuid, and which 

 contain the buds ; as in the 

 Ground Artichoke and the 

 Grouna-Artidioke. Potato. Here these parts, 



with their buds, or eyes, are all that live over winter. These thickened ends of 

 stems are called Tubers. In Fig. 59, a is a tuber of last year, now exhausted and 



