COMPOSITION' OF THE FLORA. 



87 



t'litiro coriaceous l<(aves from t-Ii<! Sauuoisian of 

 soutluM'u Frauc(5 and is an ontirciy cxiiuct. tyjx". 

 It is spars<dy roprcsentdd in tho WiJcox by ji 

 single spocios. Tlio ijenus J'rot-eoidcs was (es- 

 tablished by H(HU' for t;;(!ii<(7-aliz(!d ]irot<!ace()Us 

 types, which are w(ill i-e])res<!uted in the l'pp<»r 

 Cretaceous floras of the ciinbaynieut area as 

 well as elsewhere. It is repr<!S(ni.t(Hl in, iIk! 

 Wilcox ])y a single ^\•(ill-ulark(Ml sp(ici(w tlial^ is 

 confined to the IloUy Springs sand and (irena.da, 

 fonnatiou. 'J'lie genus KnightiopJiylhuu is 

 first proposed here for a well-marked long- 

 petiohul aquiline-toothed coriaceous fonn wliicli 

 is common at Puryear, Tenii. It is named from 

 its roseml)lance to the genus Knightia K. 

 Browai, which contains a few existing s])(!ci<!s 

 confined to the Australian region, tlioiigh a]>- 

 parontly it was represonttnl in I'hn-o]ie dm-ing 

 the Tertiary period, as alrtiady indicated. 



The genus Banksia includes 3 Wiloox species, 

 2 of which are particularly well marked and a 

 probable fruit, CarpoVithns protcoido^. It is 

 confined in the existing flora to the Australian 

 region and contains abcnit 50 species. The 

 other genus of the tribe Banksioa' is Dryantlra 

 R. Browai, which also includes about 50 exist- 

 ing species confined to tlie Australian region. 

 It is much like Banksia in its foliar characlcu's. 

 Both genei'a are alnmdant in the Euroj^san 

 Tertiary formations and undoubtedly enjt)yed 

 a more or less cosnicjpolitau range during th<( 

 early Tertiary period. Their ancestors prob- 

 ably entered the Australian region during the 

 Upper Cretaceous epoch, probal)ly ])y way of 

 the Antarctic continent, and became adapted 

 to the peculiar soils and climate, but tlie stock 

 in the Northern llemisplierci ajipears to liave 

 been imabls to stand the climatic changes and 

 competition during the Tertiary ])eriod, and 

 thus became extinct. 



The Aristolochiales is placed by some stu- 

 dents among the Gamopetala?. It includes 

 besides the Ai'istolochiacea3 the two parasitic 

 families, the Rafflesiacese and Hydneracese, 

 altogether containing about 235 existing spe- 

 cies, of which 1205 belong to the Aristolochiacea^, 

 the only family of this order represented ui 

 the Wilcox flora. The genus Aristolochia, to 

 which a typical fruit from the Wilcox is i-eferred. 

 is found in the American Upper CJretaceous and 

 in both Europe and America in the Tertiary. 

 There are about ISO existing species, all per- 

 ennial herbs or climbing vines and widely dis- 



tributed in iioth tropical and temperate re- 

 gions. Al)out 10 species are I'ound within tlie 

 UiHted States. 



TIic order Polygoiiales incdudes the singlt^ 

 family I'olygonaceiB with about 800 existhig 

 s])(>cies segi'egated in about 30 genera and 

 wi(kdy distrilnited. They embrace herbs, 

 slu-uiis, vines, and trees. The flowers are 

 mostly cyclic, and in their morphologic features 

 show some evidences of transition l)e(ween 

 the ])revious clioripel.-doiis aUiances a,nd tlie 

 Chenoi)()(liales. Exce])t tiie widely distributed 

 and much diflVrentiated lierbaceous genera, 

 Polygomim and Ivumex, the fanujy is essen- 

 tially American. The geologic history of the 

 family is practically unknown, but a large part 

 of the specific variation, particularly of the 

 tem])erate herbaceous forms, steems to be rela- 

 tixcly modern. The family is represented in 

 the Wilcox by the single genus Coccolobis, 

 wliich is represented by two speci(>s that- appear 

 to be the Eocene ])rototypes of th(! only two 

 existing arliorescent species of Polygomxceje 

 that reacli the United States (tlie sea grape and 

 the pigeon ])lum). The geims Coccolobis con- 

 tains about 120 existmg species, all confined to 

 the Amei'ican Tropics, and it appears to ])e of 

 American origin. These sj)ecies, most of whicli 

 are coastal forms, range fi-om southern Florida 

 to Mexico, Central America, Brazil, and Peru. 

 The two modern species, which are so mucli 

 like thes(> two ancestral f(U'nis in the Wilcox, 

 are strand types, found from the Florida. Keys 

 through the West Indies to th<>. northei'U coasts 

 of Soutli America. The conclusion is almost 

 irresistible that the Wdcox forms had a similar 

 range and an identical habitat. 



The genus Ruprechtia C. A. Meyer, of the 

 Polygonacese, which in(dude about a score of 

 existing species of shrubs and trees in tropical 

 and subtropical America, uicludes a species iii 

 the Tertiary of Bolivia. 



Tlie Clienopodiales (Centrospernne of Engler) 

 incdude 10 families whicli culminate in the 

 (^aryophyllacea^ and contain about 3,500 exist- 

 ing species. They a])pear iOy assorted and 

 show a wide range in floral and other morpho- 

 logic characters. Perhaps a majority are mod- 

 ern types. The single family Nyctaginaceje 

 represents this order in tlie Wilcox. 



The Nyctaginacea>, wliich inidude about 150 

 existing species, are i)redoniiuantly American 

 They occur within the limits of the southern 



