RELATION TO BOTANY. The facts relative to the phylog.eny, or ancestral development, of the vegetable kingdom supplied by palcobotany have materially aided in placing modern vegetable taxonomy upon a firm and philosophical basis.
:Many of the now recognized early errors in tax onom• might have been avoided if the path indicated by phylogeny had been followed. Nearly every change which systematic botanists have made in the sequence or grouping of living plants, in their efforts to bring supposed allied forms together, has resulted in producing a taxonomic arrangement more closely approximating the phylogenetie sequence in the evolution of the fossil ancestors. The recognition of the fact that our living flora consists merely of the remnants of that which preceded it enables us to under stand the meaning of many otherwise puzzling phenomena, such as that of monotypic genera, like Gingko, Liriodendron, Sassafras, etc.. each of which is represented by a single species more or less widely separated biologically from its near est living allies. Any apparent isolation of this kind in systematic botany was not capable of explanation by means of any known facts in connection with the existing flora.
Paleobotany has been of material assistance in solving many of the problems connected with time geographical distribution of living plants.
The genus Sequoia, represented by the redwoods (Sequoia semperrirens) and the giant trees (Sequoia gigantea) of California, is restricted in its range to a narrow belt on the west coast of the United States, but its fossil remains demonstrate that the genus had in the past a large number of species and a distribution which embraced practically the whole of North Amer ica, Europe, and Asia. Geological changes re
sulted in its extermination throughout the latter region and in all except the one limited area in the former. The genus Nelumbo is represented by two living species, one of which is restricted in distribution to Asia, the other to Eastern North America, When the fossil representatives of the genus were discovered they showed that the genus once extended over the whole of North -1me•ien and Europe, and it is now recognized that changes in environment almost eaused its extinction and left only one representative species in each continent. The problems of abnormal growths or of apparently useless organs in living plants have frequently been explained satisfac torily on the theory of atavism or reversion to ancestral characteristics when their fossil repre sentatives have been examined.
Plants have always been regarded as'excellent climatic indices. The fact that certain species or genera or families can exist only within cer tain extremes of temperature is well known, and hence it a relationship between a fossil flora and living plants of restricted climatic range can be established. it may be accepted as good evidence that the fossil flora was associated with a cli mate comparable with that of the region in which the similar living flora is now found. Fossil re mains of eyead.s and palms found in the Creta ceous and Tertiary strata in the Arctic zones prove conclusively that tropical or subtropical conditions formerly prevailed there.