2SS SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 54 



In phrases like these does Tragtts almost always particular- 

 ize about the habitat, the soil, the exposure of the wild plants of 

 Germany which he describes ; and it would not be difficult to gather 

 out of these antiquated and yet living pages definite outlines of the 

 plant associations of every part of the country with which he was 

 familiar. 



The fungi, lichens, and mosses, already alluded to under this 

 heading, are not the only plants in connection with which he per- 

 mits ecological considerations to influence his taxonomy. He 

 collocates in an unbroken series, as plants nearly allied, broad- 

 leaved houseleeks, and sedum species the leaves of which are small 

 and terete. Such a series is of course a faultless one in the judg- 

 ment of modem botany, because the structure of flower and fruit 

 is the same in all; but the case was otherwise four hundred years 

 ago, when anthology was hardly yet in embryo, and even leaves 

 were more generally received as furnishing the criteria of afl&nity. 

 Tragus had to defend the position he had taken when placing certain 

 small plants regarded as leafless in the same line with live-forever 

 and houseleek as their next of kin. He himself could not claim 

 that Sedum acre and its cognates had leaves at all. They exhib- 

 ited, he said, in what seemed to be the places for leaves, grain- 

 like things which he preferred to call acini ; and an acinus may be a 

 seed, a grain, a germ, or even a berry. He has but one argument 

 to offer in defense of this line of broad-leaved things and things 

 green though leafless, as being a natural series, and that argument 

 is purely ecological. All of them inhabit peculiarly the roofs of 

 buildings, and thrive there much better than elsewhere. Even 

 such of the species as now and then establish themselves on the 

 ground are never seen but in the most open exposures. All of 

 them everywhere avoid all protection from extremes of tempera- 

 ture, retaining their fresh verdure unimpaired under the rigors 

 of the severest winter. ^ Such ecologic groupings are of course 

 traditional, having come down from earlier times; and under such 

 defense as Tragus makes of this one, his contemporaries would 

 perhaps admit its validity despite the great diversity among the 

 members of it as to foliage. 



Another instance of this kind of procedure to which I wish to 

 call attention is the reverse of the above as to the result attained. 

 German species of the rather ample genus Veronica are placed in 

 widely sundered groups on principles as purely ecologic. In one 



' Stirp. Comm., pp. 373-380. 



