112 



l.OWEK EOCENK FLOIiAS OF SOTTII EASTI-.ltN Xdimi AMEIilCA. 



^\jU('ricii. Thoro is a single s|iecics iti Africa, 

 about Giusouthorn^Vsia, and 1 in Australia. Tlie 

 fossil species number more than 20, the oldest 

 known l)ein£; a common form in the Porucer 

 beds (Cenonianian) of lk)lu'mia and Moravia. 

 An iUbian species of Bombax described t)y 

 Fontaine is entirely valueless. There an» .S 

 species in the Ypresian of southern Ens2;laud 

 and 2 well-marked foria-; in the Wilcox flora. 

 There are 3 additional Eocene forms from 

 Chile. There are 5 or 6 Oligocene species 

 recorded from South America, France, Saxony, 

 Bohemia, and Carniola. The genus is re|)re- 

 sented in the early Oligocene (Sannoisian) of 

 southeastern I'^rance not only by the foliage 

 but l)y l)eautifully pi-eserved flowers, so that 

 tliere is little ground for questioning the cor- 

 rectness of the identifications. There are 7 

 Miocene species in Bohemia, Croatia, St\Tia, 

 and Australia. 



The family Sterculiaceffi includes about 5 

 genera and 800 existing species of mostly 

 tropical shrubs and trees which bear prev;iil- 

 ingly large, simple, or digitately lobed or 

 divided leaves. Some of the flowers are 

 apetalous and differ from those of the Mal- 

 vaceae in their 2-ceUed extrorse anthers. 

 Syncarpy is more or less complete. 



The Stercidiacere of the existing flora are 

 found on all the continents except Europe. 

 Tlie genera Sterculia, Ilelicteres, Melochia, 

 Buettneria, and Ilermannia are represented 

 by species in both the Eastern and Western 

 hemispheres. The geologic history of the 

 family extends back to the base of the Upper 

 Cretaceous but is (-oniined to a relatively few 

 genera. The most al)undant of these genera 

 is Sterculia Linne, whicli in the existing flora 

 comprises about 100 species of large-leafed 

 trees. These species are grouped into three 

 tribes nanied from the habit of the leaves the 

 Digitatse, Lobata;, and Integi-ifoha'. Tlie first 

 of these tribes ranges from Farther India to 

 Austraha and includes only one or two Ameri- 

 can species. The second is most abundant in 

 the American Tropics but is also found in Asia 

 and Africa and sliows many paraLlelisjus be- 

 tween the American and Asiatic forms. It is 

 most abundantly represented in the past 

 history of the genus. The third and largest 

 modern tribe, the Integrifolia), contains 5 or 6 

 American species, and the remainder are found 

 in ^Vsia and ^Vfrica. 



The fossil foniLs (sometimes referred to 

 Sterculii)liyllum) comprise more than 50 spe- 

 cies. More than a score are known from the 

 I'pper Cretaceous. Tliey are mostly American 

 and are i-eferal)le to tlie tribe Lobatje, which 

 niay well liave oiiginated in tlie Western 

 IIemis])iiere. The Crediieria sandstone of Sax- 

 ony and the Perucer beds of Bohemia (both 

 Cenonianian) each contain a species, and a 

 third occurs in the Turoniaii of Boiiemia. 

 Tlie otlier forms are North American and in- 

 clude s])ecics in the Raritan formation, the 

 Cheyenne sandstone of southern Kansas, and 

 ill British Columbia, a species in the Patoot 

 beds of western Greenland, 6 species in the 

 Magotiiy fomiation of the Atlantic Coastal 

 Plain, and 8 species in the Dakota sandstone 

 of the western interior region. Tiiere are less 

 than a dozen Eocene species, most of tlicm 

 confined to the lower Eocene. Thus tliere are 

 .3 species in the Paleocene of France and 

 another in the Ypresian of England, as well as 

 1 or 2 in the Denver and Raton formations of 

 the Rocky Mountain Front Range. The single 

 large Wilcox species is entirely typical and 

 shows the usual variabihty in lobation and 

 size. It appears to be filiated with Sterculia 

 snoivii Lesquereux from the American Upper 

 Cretaceous and exactly matches several exist- 

 ing species. There is a smaU-leafed species in 

 the middle Eocene (Claiborne group) of the 

 en\bayraent, which exactly matches the typical 

 Sterculia labrusca linger from the European 

 Tertiary and the existing Sterculia diversifolia 

 Don. It is closely paralleled by 2 American 

 Upjier Oetaceous species — S. minima Berry 

 and S. mucronata Lesquereux. There arc 

 more than 10 Oligocene species widely scattered 

 over Europe and about 15 Miocene species, 

 mostly European, but including a single 

 species on the east coast of Asia (Sakhalin) 

 and 2 species in Colorado, one of them espe- 

 cially well marked. There are several Pliocene 

 species in southern Europe. 



Two somewhat different species of stercuh- 

 ac(M)us capsular fruits from the Wilcox are 

 referred to a new genus, Sti>rculiocarpus. The 

 larger of these forms, S. eocenicus, seems refera- 

 ble to the subfamily Buettneriere, and the 

 smaller, S. sezannelloides , is referable to the 

 Lasiopetalese or Ilelicterese. Both are very 

 similar to the fruits from the Paleocene of 

 Sezaiuie referred to the genus Sezannella, 



