170 OF THE FULCRA, 



rhamnoides. E}2(j;L Bot. t. 425, Rhamnus cathar- 

 ticus, t. 1 629 ; or lateral as Cratcegus (or Mespilus) 

 Crus-galli, tomentom^ parvi folia, &c. 



Linnaeus observes that this sometimes disappears 

 by culture, as in the Pear-tree, Pyrus sativa, which 

 when wild has strong thorns ; hence he denominates 

 such cultivated plants tamed, or deprived of their 

 natural ferocity. Professor Willdenow, Principles 

 of Bot. t, 270, considers thorns as abortive buds, 

 and thence very ingeniously and satisfactorily ac- 

 counts for their disappearance whenever the tree re- 

 ceives more nourishment. 



The permanent footstalks of the Gum Tragacanth 

 shrub. Astragalus Tragacantha, are hardened into 

 real spines, as are the flower-stalks in Pisonia, as 

 well as the stipulas of Xanthium spinosum and the 

 Mimosce. -^Linn. Mss. 



4. Aculeus, f. 121, a Prickle, arises from the bark 

 only, and comes off with it, having no connexion 

 with the wood, as in Rosa, Riibiis (the Bramble 

 Raspberry, &c.), and Zizyphus, JVilld. Sp, PL 

 V. 1. 1102. 



This is not liable to disappear by culture, being 

 very distinct in nature from the last. 



5. Cirrus, t. 9- /. 122. A Tendril. This is indeed 

 properly called o. fulcrum or support, being intended 

 solely to sustain weak and climbing stems upon more 



