128 



LOWER EOCENE FLORAS OF SOUTHEASTERN NORTH AMERICA. 



remains of the calices of viirious species. One 

 of tliese eulices from another early Cn'taceoiis 

 species, recently describecl hy the writer as 

 Diospyros vera, is found in wliat is known in 

 the Potomac River valley as tlie Raritan for- 

 mation. Apparently the habit of accrcscencc 

 hail not been fully formed, but the calyx was 

 pei-sistent then as now and entirely like a mod- 

 ern calyx m appearance. It was four-parted, 

 as is the rule m existmg persimmons, but other 

 fossil forms had a five-parted calyx, like manj' 

 present-day tropical species. 



In the Eocene epoch, which succeeded the 

 (Cretaceous, the records of the fossil occurrences 

 of UiospjTos show that it was truly cosmopoli- 

 tsm. These records include about 20 species 

 in Siberia, Alaska, and Greenland on the north 

 and in Caiaada and various localities in Europe, 

 as well as Colorado, Montana, Wyoming, Ne- 

 vada, Oregon, Washington, and other West- 

 ern States. Unfortimately we have no Eocene 

 or later Tertiary records along the Atlantic 

 coast of North America outside the embayment 

 region, since the preserved deposits are all of 

 marme origui and contain no fossil plants. 

 There is little doubt, however, that Diospyros 

 continued to be an abundant element in the 

 arborescent flora of this area. 



Tlaere are 2 well-marked species of Dios- 

 p>TOs in the WUcox flora, one of which contin- 

 ues in this region through the Claiborne. A 

 large calyx is found in deposits of Jackson age 

 in southwestern Texas. 



There are about 24 Oligocene species, most of 

 them especially common tiirougliout southern 

 Europe. There is an American species of this 

 age in the Apalachicola group of western 

 Florida and abundaiit petrified fruits in the 

 Oligocene of the Istlunus of Panama. The 

 luxuriant forests of the Miocene have furnished 

 about 20 species of Diosp\Tos. Tlie known dis- 

 tribution at this time includes European locali- 

 ties from Spain to Hungary and American 

 records in Oregon, California, Yellowstone 

 Park, and Colorado. There are 7 Pliocene 

 species in southern Europe and in Java, and 

 the genus is still represented hi Holland. 



Tiie allied genus Royena Linne is represented 

 by splendidly preserved fruits from the oasis of 

 Chargeh in Egypt (Tapper Cretaceous) as well 

 as by 4 Oligocene and 2 Miocene species in 

 Europe. It seems never to have been cosmo- 

 politan like DiospjTos, since it has never been 



recognized in tlie Western Hemisphere. The 

 fossil history of tiie geiuis Euclea Liime was 

 evidently similar to tliat of Rovena. It makes 

 its appearance in the basal Ohgocenc of Europe, 

 where it is represented throughout the Oligo- 

 cene and Miocene epochs and becomes con- 

 fined to Africa in Pliocene and Pleistocene 

 times. 



The genus Macrciglitia De Caiidolle includes 

 9 or 10 existing species, one occurring in tro]>- 

 ical Afi-ica and the remainder in iVmerica. 

 Macrciglitia is represented by both leaves and 

 flowers in fossil floras and it has been a favorite 

 receptacle for tripartite calices, not all of them 

 of assured ])otanic identity. The oldest form 

 comes from the German Oligocene, and there 

 are 5 or 6 species in the European Miocene. 

 It has not been deflnitely recognized in Nortli 

 America, although some of the Wilcox mate- 

 rial is not unlike some European material 

 referred to Macrciglitia. 



Felix has recognized wood of this family 

 (Ebenoxylon) in the Oligocene of Antigua. 



The order Gentianalcs (Contortie of Engler) 

 includes 6 families and between 4,000 and 5,000 

 existing species. The largest famQy is the 

 Asclepiadacea?, which contains more than 2,000 

 species. The families are complexly related 

 among themselves and with the next two 

 orders, almost the only constant characters 

 being the opposite leaves and the generally 

 twisted corolla in aestivation. The Asclepiada- 

 cea?, not found in the Wilcox, shares with the 

 ApocynaceiB in the development of a latex 

 system and in other specializations, and the 

 elaborate contrivances for entomophily in the 

 Asclepiadacese reach a degree of complexity 

 almost comparable with that of the Orchida- 

 ce;e. The LoganiaccEe, also not represented in 

 the Wilcox flora, are lianas characteristic of 

 South America and Asia, which are regai-ded 

 by Engler as r(4atively primitive and possibly 

 the ancestral stock of the Gentianalcs and 

 Rubiales. The order as a whole is numerically 

 massed in the Tropics by reason of the many 

 tropical genera of the two largest families, the 

 A,sclepiadac(>;e and Apocmacca>, whicli together 

 contain three-fourths of the existing species of 

 the order. 



The family Oleaccfc, sometimes considered as 

 an order, thci Oleales, contains 2] genera and 

 about 400 existing species. Three small genera 

 are peculiar to Asia and 4 are peculiar to 



