230 BERRY— LOWER EOCENE FLORA OF [April 25, 



The family Melastomaceae is a relatively large one with about 

 150 genera and over three thousand existing species. It is almost 

 strictly tropical although some members range southward to 40 

 south latitude. It is a typically American family, seven of the fifteen 

 tribes into which the family is divided being confined to tropical 

 America, and about 2,500 of the existing species being also endemic 

 in this region. While the geologic history of this vast assemblage of 

 forms is practically unknown, there is no evidence to disprove the 

 theory that it, like the allied families Combretaceae and Myrtacese, 

 had its origin in that most prolific region — the American tropics. 



The few fossil forms that have been found, including leaves, 

 flowers and calices, have been referred to the form-genus Melasto- 

 mites first proposed by Unger. A doubtfully determined species, 

 which probably belongs to the Lauraceas, had been recorded from the 

 Upper Cretaceous of Westphalia. The only known Eocene species 

 is the well-marked form present in the Wilcox flora. Four Oligocene 

 species have been described from Bohemia, Styria and Egypt; four 

 Miocene species from Switzerland, Prussia and Croatia; and a 

 Pliocene species from Italy. 



The order Umbellales (Umbelliflorae of Engler) includes but 

 three families — the Araliacese, Umbelliferae and Cornacese, together 

 with upwards of 3,000 existing species of which more than two- 

 thirds belong to the Umbelli ferae. The three families are closely 

 related and stand somewhat apart from the rest of the choripetalous 

 orders. While undoubtedly there has been great specific variation in 

 very modern times especially among the herbaceous forms of Umbel- 

 li ferae, some members of the alliance go back as far as undoubted 

 dicotyledons have been found, and this fact is one of the strongest 

 arguments for considering its relationships to the Gamopetalae to be 

 less close than some botanists have suggested, a suggestion based 

 primarily on a consideration of the floral structures apart from the 

 morphological features of the whole plants As regards floral evo- 

 lution the Umbellales clearly mark its highest expression among the 

 Choripetalne and parallel the Gamopetalne. The flowers are epigy- 

 nous, with cyclic stamens, reduced carpels, and often reduced sepals. 

 The Araliaceae and Cornaceae are both positively and the Umbel- 

 li u-ra- doubtfully represented in the Wilcox flora. 



