• 2. 



arg5 



on 



31 



fald, 

 vheii 



:d, i 



IS 



; foil , 



or 



ion of 



done 



' foil • 



I than 



a new 



foil of 

 From 



ur feet 

 at the 



ore one 



It. 



At 



e 



fe be- 



>t; 



: and 



now a 



lej 



joints 



e. 



P 



if 



an 



be- 



otato, 

 leaves 



aei 



f ai 





ds, 



a 



Sect. XVII 



ROOTS AND BARKS 



475 



and like the viviparous polygonum ; but differs in this d..unaft^^^^^^ 



that in all thofe, I believe, the flowers are barren uyef ed to bear 



.re on the fummit of the fpike of polygonum 



o 



feeds 



parum 



thofe 

 but in th 



al potato 



there was alfo a feed-bearing 



flower at the fummit of the flem, and the new roots only at the la- 

 teral joints. I ftould hope this proliferons variety by cult.vat.ou may 

 become permanent, and give rife to a new fpecies, which may pro- 

 duce both aerial potatoes and fubterraneous ones, a twofold v■v:paI0.^s 



progeny 



The curling of the leaves of potatoes, which 



ded with fo 



D 



diminution of the quantity and fize of the new roots, is fup- 

 pofed to be owing to their continued propagation by fubterraneous 

 buds or root-wires, inftead of by feed ; that hence they acquire he- 

 reditary difeafes, like the canker or gangrene of apple trees, which 

 have for one or two centuries been propagated by grafting the fcions, 

 as mentioned in Sed. IX. 3. 4- and XV. i. 4. Hence by fowmg the 

 feeds of potatoes, and cultivating the roots thus produced, new va- 

 rieties may probably be foon acquired, exempt from the difeafe of the 

 curled leaf, and which may be as good in other refpeds as thofe 

 which have been too long propagated by their roots. Some have 

 neverthelefs affirmed, that they have feen curled potato- plants in the 

 fecond year from the feed ; and others, that they have feen numer- 



feds on thef 



led leaves ; and others, that the pot 



th 

 th 



foil 



f which are curled, remains hard, and lefs diffolubl 

 hich I have myfelf witiK 



ffed. More obfe 



are. 



wanted to elucidate this fubjed 



Another caufe of the degeneracy of potatoes h 



arifen, I d 



/ 



\ 



from planting the leaft inftead of the largeft roots, fee Seft. XVI. 5. 

 and which confequently poffefs lefs vigorous vegetation, as buds and 

 bulbs fo exaaly refemble the parent plant. Thus the fmall bulbs, 

 which arife from tulip-roots, will produce a rather larger bulb an- 

 nually for three or four years, as I am informed ; but it is the large 



3P2 new 



t 



^ 



•t 



