210 TREE ANCESTORS 



Oligocene records are all European, and include France, Tyrol, 

 Italy and Prussia, the last found in the celebrated Baltic amber 

 deposits. Two-thirds of the known Oligocene sumachs have been 

 found in France, and the bulk of these along with a most interesting 

 and varied fauna and flora, come from the gypsiferous clays of 

 southeastern France. At the time these clays were being formed 

 and these fossil plants and animals were living the region was one 

 of retreating seas and coastal evaporating lagoons in which hosts 

 of fishes perished and were fossilized, along with insects, and ter- 

 restrial animals and plants. There is considerable of an African 

 flavor to this life with which the fossil sumachs are in accord. In 

 most of the tree histories the reader will note a falling off in the 

 number of forms during OHgocene time due to the climatic condi- 

 tions which were rather warm and dry and which were more favor- 

 able for plants of what are now exotic types rather than of the 

 familiar temperate trees, but the sumachs are an exception to this 

 general condition having been particularly adapted to the climate 

 of the OHgocene. 



During succeeding Miocene times the sumachs reached their 

 maximum development and probably were more abundant and wide- 

 spread than they are at present, although only about 70 Miocene 

 species are actually known. They were especially abundant about 

 the shores of the Mediterranean in the latter half of the Miocene. 

 Four of these Miocene sumachs were survivors from Oligocene 

 times. In Europe these Miocene sumachs have been recorded 

 from southern Spain to eastern Greece, and they were especially 

 varied in France, Styria and Croatia. Every European region with 

 Miocene plant beds has its species of sumach. In North America 

 Miocene sumachs have been found in Maryland and Virginia on 

 the Atlantic coast, and in Oregon and Cahfomia on the Pacific 

 coast. Seven different forms are known from Cahfomia. In the 

 interior they have been found in Idaho, Nevada and Colorado. In 

 the deposits of the celebrated fossil lake at Florissant in the Colorado 

 Rockies, 7 different sumachs have been found entombed, and this 

 vista furnished by the life of this tiny lake basin suggests that 

 similar assemblages must have been present during Miocene times 



