48 Elementary Species 



may be cultivated in the same garden without 

 any real danger of their intercrossing. They 

 remain as pure as under perfect isolation. 



It is very interesting to observe the aspect of 

 such types, when growing near each other. 

 Hundreds of rosettes exhibit one type, and are 

 undoubtedly similar. The alternative group is 

 distinguishable at first sight, though the differ- 

 entiating marks are often so slight as to be 

 traceable with difficulty. Two elementary spe- 

 cies occur in Holland, one with narrow leaves in 

 the western provinces, and one with broader 

 foliage in the northern parts. I have cultivated 

 them side by side, and was as much struck with 

 the uniformity within each group, as with the 

 contrast between the two sets. 



Nearly all organs show differences. The 

 most marked are those of the leaves, which may 

 be small or large, linear or elliptic or oblong and 

 even rhomboidal in shape, more or less hairy 

 with simple or with stellate branched hairs, and 

 finally of a pure green or of a glaucous color. 

 The petals are as a rule obcordate, but this t\T)e 

 may be combined with others having more or 

 less broad emarginations at the summit, and 

 with differences in breadth which varv from al- 

 most linear types to others which touch along 

 their margins. The pods are short and broad, 

 or long and narrow, or varying in sundry other 



