88 



LOWER EOCENE FLORAS OF SOUTIIEASTEKX NORTH AMERICA. 



I'nited States on tli(> nin-th and Chile and Ar- 

 p;(>ntiua on the south. The iicuus I'isouia 

 Plumier, tho only genus thus far found in the 

 Wilcox flora, is represciited by throe well-marked 

 species. It includes about 40 existing species, 

 which Uve chiefly in the American Tropics, and 

 contains the only arborescent form of the family 

 found within the United States. It has an 

 extended geologic history, well-marked forms 

 l)emg found in the European and American Uji- 

 per Cretaceous. The Wilcox species were un- 

 doubtedly strand types, as are so man\' of the 

 modern species which inhabit the sea beaches, 

 the shores of salt-water lagoons and marshes, tlie 

 scrub of beach ridges, and the jungle behind 

 them. In the existmg flora Pisonia is associated 

 with Pithecolobium, Reynosia, Metopium, Aca- 

 cia, Bumelia, Cordia, Coccolobis, Ocotea, Fa- 

 gara, Mimusops, Conocarpus, Cassia, Eugenia, 

 Anona, Ficus, and the like, exactly as it was 

 during the Wilcox time. Species of Pisonia 

 occur in the Upper Cretaceous of the Atlantic 

 Coastal Plaui (Black Creek formation), as well 

 as in the middle (Claiborne) and upper (Jack- 

 son) Eocene. 



The order Ranales appears to me to be a 

 highly umiatural assemblage, which doubtless 

 explains the prolonged discussion and wide range 

 of opinion regarding its true status. As treated 

 in Engler and Prantl, it includes 16 families 

 and more than 4,000 existing species. Though 

 most of these forms have a distinct calyx and 

 corolla, this feature is combmed with such 

 primitive features as apocarpy and hypogynv, 

 by a well-marked tendenc}' to indeflnite repeti- 

 tion and spiral arrangement of the floral mem- 

 bers. I have removed the Lauracese, which 

 contain a fourth of the existuig species, to a 

 place in the more evolved order Thymeleales. 



The Ranales as a whole show no very close 

 filiation with earlier allied types. They include 

 forms that are more nearly monocotyledons than 

 dicotyledons (Nj-mphseaceaj), and many bota- 

 nists (as Wieland, Arber, and Hallier) see in 

 them the zenith of evolution of the Mesozoic 

 Cycadophytes and thus regard them as repre- 

 senting the ancestral stock from which the 

 angiosi^erms were descended — a most remark- 

 able derivation, apparently, if any except floral 

 features are considered.' 



1 For <iiseussion of this theory see recent paper.s by Wielau'l, Arber 

 and Parkin, and Uallicr. 



Since I regard the Ranalian alliance as a 

 plexus containing unn-laled elements, any 

 extended consideration of their geologic histor}^ 

 would be fruitless. Certain forms are well 

 represented among the oldest known angio- 

 sperms in the middle Cretaceous. Only two 

 Ranalian families, the Magnoliaceaj and Anona- 

 cex, are represented in the Wilcox flora and 

 these two are both natural groups, closely re- 

 lated and typically Ranalian. 



The family Magnoliaceas comprises about 70 

 existing species segregated into 9 or 10 genera, 

 by far the largest of which is the genus Mag- 

 nolia, which includes about 21 species of eastern 

 and southern Asia, southern Mexico, and the 

 eastern United States. The famih^ is mauily 

 tropical, and most of the existing forms occur 

 in southeastern Asia, the magnolias of that 

 region being largely found in tropical uplands. 



There are many apparent anomalies in the 

 distribution of the recent forms. Thus, none 

 are native in Europe, although Magnolia per- 

 sisted in that region as late in geologic time 

 as the early Pleistocene. Only one genus, 

 Drunys Forster, occurs in South America or 

 Australasia and a species is recorded by 

 Deane from the Tertiary of New South 

 Wales. This genus extends southward from 

 Mexico along the Andes to Cape Horn and 

 from New Zealand and Australia northward 

 to Borneo, a range which suggests that it will 

 eventually be recorded from the Antarctic 

 Upper Cretaceous or Tertiary deposits. There 

 is a smgular pairing of fonns of the Magno- 

 liacea? in southeastern Asia and southeastern 

 North America. For example, Magnolia in- 

 cludes 14 Asiatic species and 7 American; 

 Talamna Jussieu is represented by 3 species in 

 Farther India and 1 in the West Indies; Lirio- 

 dendron Linne and Schizandra Michaux each 

 contain 1 species in Asia and 1 in North 

 ^imerica; and Illicium Linne includes 5 Asiatic 

 species and 2 iVmerican. The genera IMichelia 

 Linne (13 species) and Kadsura Jussieu (7 

 species) are confined to southeastern Asia, and 

 Zygogynum Baillon is confined to tho island of 

 New Caledonia. 



The leaves of ah the ^lagnoliaceie arc entire 

 and are more or less elliptical. They have a 

 coriaceous texture, many of them are ever- 

 green, and they possess a characteristic camp- 

 todrome venation. Of the 7 species of Mag- 



