452 ANNUAL REPORT SMITHSONIAN INSTITUTION, 19 3 8 



a novelty in the plant kingdom, where did it come from and of what 

 sort were its ancestors? Such questions as these are ever present 

 in the thoughts and speculations of the curious people who search 

 for origins among the scanty and often illegible documents scattered 

 through the rocks in the course of geological history. As we follow 

 a group, a family, or a genus through the pile of sedimentary rocks 

 we reach at length the earliest records, and though it may seem that 

 the quest is ended, there always remains doubt and uncertainty 

 whether the lack of still older fossils may be due to imperfection 

 of the record. It was only in exceptional circumstances that samples 

 from nature's garden were preserved in the herbaria of the rocks. 

 As we pass from rocks containing the most ancient fossils that can 

 be regarded with confidence as undoubted allies of the maidenhair 

 tree to rocks older still, we discover fossil leaves which may or may 

 not be the foliage of trees of the same lineage. Leaves from Permian 

 and Carboniferous strata described under various names, Gink- 

 gophyllum, Psygmophyllum, and others, though similar in form to 

 those of Ginkgo, do not afford definite evidence of real affinity. The 

 most promising of the Paleozoic genera is known as Saportaea, called 

 after a French paleobotanist, the late Marquis of Saporta, a genus 

 founded on leaves first discovered in Permian rocks of Virginia and 

 more recently in central China: this genus may be allied to Ginkgo; 

 but that is as far as one can go. The ancestral stock may be recognized 

 some day in the petrified litter of the coal period forests; but as yet 

 we can only guess whence the Ginkgo group came. We must for the 

 present be content with the knowledge that trees of the Ginkgo type 

 had risen to prominence before the close of the Triassic period and 

 continued to flourish and occupy fresh territory in the course of the 

 Jurassic period: they held their own in the Cretaceous period and in 

 the earlier stages of the Tertiary era, but as the Quaternary age dawned 

 comparatively few examples remained. 



PART II 



OTHER MEMBERS OF THE GINKGO FAMILY 



Each of the families to which botanists have assigned the higher 

 plants, both Angiosperms and Gymnosperms, usually contains 

 several genera differing, it may be, widely in appearance and yet 

 possessing certain features in common believed to be indicative of 

 close relationship. It is generally agreed that such trees as larches, 

 cedars, firs, and pines are all members of one family which in the 

 course of time have deviated in their several ways from some ancestral 

 prototype. These genera are believed to be closely related one to 

 another because they possess in common certain features, especially 

 those exhibited by the fertile shoots, which suggest descent from a 



