14 



THE PHYLOGENETIC METHOD IN TAXONOMY. 



in 1920. These at once revealed a striking similarity between the traditional treatment 

 of the species as exemplified by Linnaeus, Bentham, Gray, and others and the ecological 

 treatment based upon the fullest recognition of evolutionary processes. This was not 

 merely evident in the total number of species, but with rare exceptions the numbers 

 were also in close agreement for the 91 genera considered. While the evidence can 

 not, in the nature of the case, be regarded as conclusive, it is strongly suggestive of 

 the fact that the traditional concept and the ecological concept of the species are based 

 upon the same phylogenetic unit and are essentially identical. 



The scientific basis of species. — The basic essentials of the evolutionary treatment of 

 species are a fixed species concept and their determination primarily in the field. In 

 spite of occasional exceptions, the traditional species concept, crystallized by Linnaeus, 



Table 2. — Number of species in representalive genera. 



Ranunculus. . 



Aquilegia 



Delphinium . . . 



Aconitum 



Draba 



Arabis 



Lepidium 



Erysimum . . . . 

 Lesquerella. . . 



Roripa 



Viola 



Geranium 



Arenaria 



Glaytonia 



Polygonum. . . 



Eriogonum 



Chenopodium . 



Atriplex 



Salix 



Euphorbia . . . . 

 Dodecatheon. . 

 Polemooium.. . 



Phlox 



Gilia 



Gentiana 



Frasera 



Phacelia 



Lithospermum 

 Krynitzkia. . . . 



Mertenaia 



Lappula 



Pentstemon. . . 



Mimulua 



Castilleia 



Pedicularia. . . . 



Monarda 



Rosa 



Potentilla 



Fragaria 



Geum 



Lupinus 



Astragalus . . . . 



Aragalua 



Vicia 



Lathyrus 



Trifolium 



Saxifraga 



Heuchera 



Coulter 

 and 



Nelson, 

 1909. 



Rydberg, 

 1917. 



Clement.3, 

 1913. 



Ribes 



Quercua 



Epilobium 



Oenothera 



Mentzelia 



Opuntia 



Ligusticum 



Lomatium 



Galium 



Valeriana 



Gutierrezia 



Grindelia 



Chrysopsis 



Haplopappua . . . 

 Chryaothamnua 



Solidago 



Aster 



TowQsendia. . . . 



Erigeron 



Antennaria 



Helianthua 



Hymenopappus. 



Actinella 



Artemisia 



Arnica 



Senecio 



Carduus 



Crepis 



Agoseris 



Tradescantia . . . 



Allium 



Zygadenua 



Sisyrinchium . . . 



Juncus 



Carex 



Agrostis 



Stipa 



Poa 



Featuca 



Bromus 



Agropyrum . . . . 

 Elymus 



Total 



Average No. of 

 species per 

 genus 



Coulter, 

 1885. 



Coulter 



and 

 Nelson, 

 1909. 



Rydberg, 

 1917. 



elements, 

 1913. 



