108 



LOWER EOCENE FLORAS OF SOUTHEASTERN NORTH AMERICA. 



species from tl>e soutli of England hav(\ been 

 referred to it by EttLngshausen, and it lias also 

 been recorded from tlie Miocene of the island 

 of Saldialin. The greater number of Cupania- 

 like forms have, however, been referred to the 

 geuus Cupanites Schimper, of which 9 or 10 

 species have been described, and with the excep- 

 tion of extremely doubtful forms from the 

 l^pper Q-etaceous of New Zealand and the 

 Tertiary of Australia, the oldest authentic oc- 

 ciu-rences are the two species of the Wilcox 

 flora. There is a third species m the overlyuig 

 Claiborne group of the Mississippi enibayment. 

 The oldest European form comes from the late 

 Oligocene of Styria. Miocene species are 

 recorded from Germany, Bohemia, Austria, 

 Croatia, and Hiuigary. 



The genus Dodonfea Linne, often made the 

 type of a distinct family, the Dodonwaceffi, 

 includes about 50 existing species four-fifths 

 of which are Austrahan. Dodonsea viscosa 

 Linne is cosmopolitan in the Tropics and there 

 are one or two additional species in the Ameri- 

 can Tropics, as well as one in the Hawaiian 

 Islands and another m Madagascar. The 

 genus (including Dodonjeites) was evidently 

 widespread in fornier times and more than a 

 score of fossil species, based on both leaves and 

 fruits, have been described. The oldest known 

 forms are two species in the Ypresian of the 

 south of England and the two contemporane- 

 ous species in the Wilcox, which are repre- 

 sented by both leaves and characteristic 

 fruits. There are 5 Oligocene species in France, 

 T3T0I, Bohemia, and Styria, and 10 Miocene 

 species in Prussia, Baden, Switzerland, Bohe- 

 mia, and Croatia. A well-marked species 

 occurs in the Claiborne (Lutetian), rangmg 

 along the Claiborne coast from northeastern 

 Georgia to central Louisiana. 



It is impossible from the known facts to 

 determine the place of origin of the family, but 

 certain genera were obviously evolved toward 

 the close of the Lower Cretaceous in ecjuatorial 

 America and have hved there or in adjacent 

 areas throughout the long stretch of time until 

 the present. 



The order Rhanmales includes about 1,000 

 existing species of slirubs, trees, and vines, 

 about equally divided between the families 

 Rhamnacesc and Vitaceae. It closely parallels 

 the Sa|)indales in its floral development, but is 

 distinguished by its mostly tetracylic flowers 



with opposite stamens, many of th(>ni lucking 

 a coroUa. The leaves are simple and typically 

 alternate. Of the two families only the 

 Rhanmaceas is represented m the Wilcox flora. 



The family Rhanrnacese (Frangulacese) in- 

 cludes 47 genera and about 500 species of 

 shrubs and trees, mostly of the Tropics, though 

 several genera extend for considerable dis- 

 tances mto the Temperate Zone, the genus 

 Rhamnus m particular bemg mostly extra- 

 tropical in the Northeni Hemisphere. The 

 genera Zizyphus, Adelia, and Gouania are 

 found in aU tropical countries. Almost half 

 the genera are common to more than one con- 

 tmental area. America has the greatest num- 

 ber of pecuhar genera (15) with about 85 

 species. Two monotypic genera are confined 

 to Asia, 5 genera, including the large genus 

 Phylica Linne, which together mclude about 

 70 species, are confined to Africa, and 5 genera, 

 including the two large genera Sp\Ti(hum 

 Fenzl and Cryptandra Smith, in all about 70 

 species, are confined to Australia. 



Ten or 11 genera, of which 5 are represented 

 in the Wilcox flora, are found fossil, the three 

 largest being Rhanmus, PaUurus, and Zizyphus. 

 The genus Rhamnus Linne, which is cosmo- 

 politan in the northern warm temperate and 

 subtropical zones, includes about 70 existmg 

 species. There are considerably more than 

 100 fossil species, mostly well characterized, 

 the leaves of which arc simple, commonly 

 entire, and have ascending secondaries and 

 closely spaced fine percurrent nervilles. A 

 dozen or more species have been described from 

 the Upper Cretaceous, the genus appearing in 

 the Cenomanian in both Europe (Niederschoena, 

 Saxony) and America (Raritan formation). 

 There are 6 species in the Dakota sandstone, 2 in 

 theMagothyfonnation, 1 in the Atane, and 2 in 

 the Patoot beds of Greenland. The genus is 

 represented in the Montana group and the 

 Laramie formation of the western interior 

 region and in the Senonian of Westphalia. 

 There are about 30 Eocene species, most of 

 them North American. Species of Rhamnus 

 are very common in the Raton and Denver 

 formations along the Front Range of the Rocky 

 Momitains and from the base to the top of the 

 Wilcox. There are 4 species in the Raton, 

 8 in the Denver, and 6 in the Wilcox. The 

 genus is also well represented in the later 

 Eocene along the Pacific coast and in western 



