"POLYCARPIC" JIMSON WEED 



The habit and character of this mutant is strikingly different from the normal plant 

 shown in (Fig. 7). The most conspicuous peculiarities are its narrow entire leaves 

 and its slow growth. (Fig. 8.) 



a distinct type from its narrow, slightly 

 toothed leaves. Fig. 8 is typical in 

 habit for pot-grown plants inasmuch 

 as the stems are weak and inclined to 

 droop when grown under greenhouse 

 conditions. In Fig. 12, a typical " Cock- 

 lebur" seedling is shown at the left 

 beside a normal from the same pedigree. 

 The differences are such that these 

 mutants can usually be picked out in 

 the seedpan. 



'' Poinsettia" (Fig. 14). — The mutant 

 "Poinsettia" is one of the most distinct 

 in habit of all the mutants so far dis- 

 covered. Its long, narrow, dark-green 

 leaves are clustered at the ends of the 

 branches in a fashion suggestive of the 

 plant from which it has been named. 

 Masses of adventitious buds often 

 extrude from the young stems, causing 

 irregularities in the branching and in- 



creasing its strangeness of appearance. 

 For comparison with this and the next 

 mutant to be described, there is shown in 

 Fig. 13 a few-noded nonnal plant on the 

 left and a many-noded normal on the 

 right. 



"A^. 5." — The original plant of the 

 mutant provisionally designated by "N. 

 vS.," the initials of the words New 

 Species, is represented in Fig. 15. This 

 plant proved sterile in several attempted 

 crosses with normals although fertile 

 with itself and with its own offspring 

 produced by self-pollination. Further 

 tests have shown that the mutant differs 

 from all others investigated in that it 

 breeds true and seems to ha\^e estab- 

 lished itself as a distinct new race which 

 is almost entirely, if not absolutely, 

 sterile with other forms. This physio- 

 logical incompatability between a muta- 



115 



