130 



LOWER EOCENE FLORAS OF SOUTHEASTERN NORTH AMERICA. 



the l'])])!'!- Cretaceous eoiiie fi-oiii the Dakota 

 saiidslono of the western interior States and 

 from Australia, Westphalia, and Saxony. 

 More than a score of Eocene species are widely 

 distributed. Of 5 species in the Wilcox flora 

 sev(>ral are exceedingly well marked and 

 common. There are also 5 species in the 

 Ypresian of southern England. Other Eocene 

 records mclude GreeiUand, New Zealand, and 

 Chile. The score or more of knowm Oligocene 

 species are confined to European localities. 

 The Miocene species number about 25, mostly 

 confined to Europe, but recortUxl also from 

 Australia. 



Fossil fonns have been sparingly refen-cd to 

 the followhig genera: AUamanda, Hsemadict- 

 yon, and Thevetia have been recognized liy 

 EngeUiardt in the early Tertiary of Chile. 

 Alyxia, Alstonia, Cerbera, and Tabernsemon- 

 tana have been recognized m the Em-opean 

 Tertiary by different students. Tlie genus 

 Neritiniimi Unger mcludes 4 or 5 species in the 

 European Miocene. Tlie genus Plumeria con- 

 tains 4 Miocene species m Europe and a Pliocene 

 species in Brazil. The genus Echitonium 

 Unger mcludes more than a dozen fossil species. 

 There are 5 species m the Eocene, includmg a 

 well-marked form in the Wilcox flora; 2 m the 

 Oligocene and 5 in the Miocene of Europe. 



The genus Nerium Linne contams only 3 or 4 

 existing species of shrubs or trees in the 

 warmer parts of Eurasia. However, the com- 

 monly cultivated Nerium oleander Lume of the 

 Levant grows to a relatively large size and is 

 extensively nattiralizcd in Florida, Bermuda, 

 and the West Indies. Saporta recorded an 

 Upper Cretaceous species, Nerium rohlii, from 

 the Campanian of Westphalia, but it is almost 

 certainly a member of the Myrtacese and not a 

 Nerium. Undoubted species do occur in the 

 Eocene of Em-ope, including the remains of a 

 characteristic flower from the Paris Basin. 

 There are several Oligocene and Miocene 

 species in Europe, and the existing Nerium 

 oleander or its immediate ancestor occurs in the 

 Pliocene of southern Europe in France and 

 Spain. The Wilcox species ApoeynophijUum 

 iahellarum is \evy suggestive of Nerium, but tlie 

 genus is not certainly known in the Western 

 Hemisphere. 



It may be noted that with tlic exception of 

 species of Apocynophyllum, which are not 

 certainly identified, the family is not repre- 



sented in tlie abundant knowni Upper Creta- 

 ceous floras of the world, which might indicate 

 that it origmated in the Southern Hemisphere. 



The order Polemoniales or Tuliiflora) (not the 

 Tubiflora?. of Engler, which includes the orders 

 Polemoniales and Personales, here regarded 

 as distinct) contams the foiu* families Convol- 

 vulace;¥, Polemoniacea", Hydrophyllacea\ and 

 Boraginacea'. The first tlu-ee are character- 

 istically American. The Convolvulaceae are 

 chiefly tropical, and the largest family, the 

 Boragmaceae, is typically developed in the North 

 Temperate Zone. 



The family Boraginacea?, the only one of the 

 order known in the Wilcox flora, contains 

 about 8.5 genera and 1,600 existmg species, 

 clucfly of widely distrilmted North Temperate 

 herbs and shrubs, or of trees m tropical coun- 

 tries, characterized by alternate, exstipulate, 

 mostly entire leaves. The known fossil forms 

 are few and of slight significance. They com- 

 prise for the most part Tertiary remains de- 

 scribed as species of Boraginites and Helio- 

 tropites. The family is represented in the 

 Wilcox by two species of Cordia, a genus that 

 contains about 2.30 existing species of shrubs 

 and trees of the warmer regions of both hemi- 

 spheres, especially the western. There is a 

 species in the Upper Cretaceous of the Missis- 

 sippi embayment area (Tuscaloosa formation) 

 and a Miocene species in Europe. Early Ter- 

 tiary forms arc recorded .from Clnle by Engel- 

 hardt and from Tasmania by Ettingshausen. 

 The slight evidence available indicates that 

 the genus originated in the American Tropics 

 and that the bulk of the family is of late Ter- 

 tiary origin. 



The order Personales or Labiatiflor.'e in- 

 cludes 16 families distmguisiied from the 

 Polemoniales by the zygomorphism of the 

 flowers. The specific difi'ercntiation is great 

 and the lines of descent arc confusing. The 

 largest famihes are the Labiatre, which con- 

 tains more than 3,000 existing species; the 

 Scrophulariacere, which contains about 2,500 

 species; the Acanthacese, which comprises about 

 2,000 species; and the Sohuiacea', which com- 

 prises about 1,800 species. Two of the 16 

 families, the Verbenacea) and Solanacese, are 

 represented in the Wilcox flora. 



The family Verbenacea) includes about 73 

 genera and 1,300 existing species of widely 

 distributed luu'bs, shrubs, or, in tropical coun- 



