LANDMARKS OF BOTANICAL HISTORY GREENE 245 



morphology, which, at least for the moment, is held subordinate 

 to the qualitative. 



After Ruta there is at once a return to the line of the quadrangu- 

 lar stem and opposite leaf. The genus is now Hypericum, and five 

 species of it are described and figured. These harmonize with the 

 main series as to an undivided foliage set oppositely and at regular 

 intervals up and down square stems; and also as being notably 

 odoriferous even if not distinctly aromatic like labiates. At the 

 same time they have manifest points of contact with rue, that 

 genus which they immediately follow; for their leaves are dotted, 

 and small flatly opening yellow flowers crown the stems and bran- 

 ches. Next after hypericum stands the undershrub, Santolina, an 

 anthemideous composite; and, viewed in the light of twentieth- 

 century taxonomy certainly rue and hypericum and santolina 

 placed in line together make a motley order; but, what we are here 

 in quest of is, the set of principles on which sixteenth-century 

 taxonomy was grounded. We are certain that Tragus had his 

 taxonomic reasons for locating santolina where he did, for he states 

 them. Every one who knows the plant is aware of its being 

 notably odoriferous; and he gives as one reason why it may well 

 stand next hypericum the fact that its aroma is that of hypericum 

 intensified. Now on the other side we shall find santolina flanked 

 by two labiate plants; and in respect to its mode of growth, and its 

 aspect as clothed thickly with small grayish foliage, Tragus says 

 that in these things it well resembles lavender and hyssop and 

 thyme. So then, judged by the criteria employed at that period, 

 this was not a motley arranging of things. 



From santolina there is a return to labiates. Two species are 

 figured and three described. We wish to know why he thus sepa- 

 rated them from the rest of their line. .It would be interesting if 

 we could learn his reasons for intruding almost into the midst of 

 the line of the mintworts Asarum, Ruta, the whole series of the 

 Hypericum species and Santolina. There is one thing which gives 

 to these last members of the line of labiates an aspect very unlike 

 that of the others; for their leaves are much dissected, while in 

 the line of more than thirty that precede rue and hypericum there 

 is not one that displays any other than simple leaves. This short 

 concluding series consists of compound-leaved species of the genus 

 Teucrium. Did Tragus, blinded by foliage so exceedingly different, 

 fail to see that these are true allies of that simple-leaved series 

 that has been interrupted by rue and hypericum? We have the 

 most positive proof that he did perceive the relation; for he says 



