PALEOBOTANY BERRY. 



403 



Fig. 40. — Restoration of lower Eocene Dalbergias from Tennessee (after 

 Berry) much reduced. 



Another genus belonging to this alliance, Dalbergia, to which the 

 rosewood of commerce belongs, is represented by four species. The 

 leaves of two of these combined with the characteristic one-seeded 

 pods as they occur in the clays of western Tennessee are shown 

 in the restoration, 

 figure 40. 



One other genus 

 of legume deserves 

 special mention, 

 since it has an 

 abundance of fossil 

 leaves and pods. 

 This is the genus 

 Cassia, to which the 

 senna, as well as our common herbaceous sensitive plants belong. 

 The modern cassias range from herbs to trees and are very abundant 

 and varied, between three and four hundred species having been 

 described from the warmer temperate and tropical climes of all the 

 continents. It is especially common in tropical America and had a 



long geological 

 history extending 

 back to the Upper 

 Cretaceous. Over 

 a dozen species 

 have been brought 

 to light in the Ter- 

 tiary bordering the 

 Gulf of Mexico, 

 and a restoration 

 of one of these 

 from the lower 

 Eocene, in which 

 both the pods and 

 leaflets were pre- 

 served, is shown in 

 figure 41. 



The genus Pali- 

 urus of the family 

 Rhamnaceae 

 (Buckthorn) is of 

 especial interest, not only because it is represented by the very char- 

 acteristic fruits as well as by the leaves, but because it has such an 

 extended geologic history and was formerly cosmopolitan. In the 

 later Tertiary it dwindled, and in the existing flora it has only two 

 species which are found from southern Europe through southern 



Fi i. 41. — Restoration of a Cassia abundant in the lower Eocene of Missis- 

 sippi and Tennessee (after Berry), X 1/2. 



