CLASSIFICATION OF PLANTS BY EVOLUTION. 



141 



P.S. — After the preceding lecture was written I met with a paper on 

 " The Phylogeny and Taxonomy of Angiosperms," by C. E. Bessey, 

 Ph.D., published by the Botanical Society of America, 1897 ; and it was 

 satisfactory to know that from the researches of Schimper and Lesquereux 

 upon fossil plants of the Cretaceous, Eocene, and Miocene floras of the 

 United States these authors follow almost precisely the same general lines 

 herein suggested by myself as based upon morphology. Thus Dr. Bessey 

 summarises the results as follows (abridged). He places Monocotyledons 

 first because of their simpler structure ; but I regard this as not indicat- 

 ing primitive but degraded features, the result of an aquatic medium. 



"It is probable that Monocotyledons and Dicotyledons appeared at 

 about the same time, namely, early in the Mesozoic or late in the 

 Palaeozoic. 



" The hypogynous Monocotyledons appear to have preceded the 

 epigynous ; and similarly the petaloideous, hypogynous species seem to 

 have somewhat preceded the spadiceous * and glumaceous species. 



" Apparently the Thalamirlone and Calycifione are the two earlier 

 types of the Dicotyledons. 



" The Bicarpellahe [common in the Gamopetahe, Labiates, &c] and 

 Infers [inferior ovaries] appear to have developed later than the other 

 types, and to have rapidly increased to the present time. 



" In the development of the *Bicarpellataj, the Polemoniales and 

 Gentiales [with regular flowers] preceded the Personales and Lamiales 

 [with irregular bi-symmetrical flowers]. 



" 1 Polype taly ' appears to have been the common condition in the 

 Cretaceous, Eocene, and Miocene periods. 



4< The first modification from polypetaly probably was in the direction 

 of apetaly [by degradation], a condition reached by many plants in the 

 earlier periods, but by relatively smaller numbers in the present. 



" Gamopetaly, from small beginnings, has increased rapidly to the 

 present. 



" Hypogyny has measurably decreased, while epigyny has corre- 

 spondingly increased." 



The author has given an elaborate scheme as to the distribution of 

 orders on evolutionary lines, but it appears to be rather too speculative 

 to be altogether trustworthy. 



* The Aroidea and Lemnacetz are undoubtedly degraded aquatic forms 



