140 Retrograde Varieties 



hedgehog burweed, a stout and common weed 

 of the western States. Its latin name is Xan- 

 thium canadense or X. commune and the form 

 referred to is named by Mr. Cockerell X. Woo- 

 toni, in honor of Professor E. 0. Wooton who 

 described the first collected specimens. 



The burs of the common species are densely 

 covered with long prickles, which are slightly 

 hooked at the apex. In the new form, which is 

 similar in all other respects to the common 

 cocklebur, the burs are more slender and the 

 prickles much less numerous, about 25 to the 

 bur and mostly stouter at the base. It occurs 

 abundantly in New Mexico, always growing 

 with the common species, and seems to be quite 

 constant from seed. Mr. Cockerell kindly sent 

 me some burs of both forms, and from these I 

 raised in my garden last year a nice lot of the 

 common, as well as of the Wootoni plants. 



Spineless varieties are recorded for the bas- 

 tard-acacia, the holly and the garden goose- 

 berry (Ribes Grossularia, or R. Uva-crispa). A 

 spineless sport of the prickly Broom (Ulex eu- 

 ropceus) has been seen from time to time, but it 

 has not been propagated. 



Summarizing the foregoing facts, we have ex- 

 cellent evidence of varieties being produced 

 either by the loss of some marked peculiarity or 

 by the acquisition of others that are already 



