I9I4.] SOUTHEASTERN NORTH AMERICA. 151 



ten species of the southeastern Asiatic area. These range from the 

 northwestern Himalayan region, where they extend a short distance 

 north of the Tropic of Cancer, through farther India and Burma 

 to Java and the Phihppines. The pistillate flowers are small and are 

 grouped in paniculate spikes. They develop into small drupe-like 

 fruits, each of which is connate at the base to a large expanded tri- 

 alate involucre. 



A single little known species, rarely represented in even the larger 

 herbaria, occurs in Central America and is the type and only species 

 of the genus Oreomnnnea of Oersted. This is much more restricted 

 in its range than are its kin beyond the Pacific. Oreomnnnea is very 

 close to Engelhardtia, and for the purposes of the paleobotanist the 

 two may be considered as identical since they represent the but 

 slightly modified descendants of a common ancestry which was of 

 cosmopolitan distribution during the early Tertiary. The present 

 isolation of Oreomnnnea furnishes a striking illustration of the enor- 

 mous changes which have taken place in the flora of the world in the 

 relatively short time, geologically speaking, that has elapsed since the 

 dawn of the Tertiary. 



The principle has frequently been enunciated that when closely 

 related forms are found in the existing flora of the world, restricted 

 in range and isolated from their nearest relatives, or when other 

 existing genera are monotypic, it is quite safe to predict an interest- 

 ing and extended geological history. Engelhardtia proves to be an- 

 other illustration of this principle, for its peculiar three-winged fruits 

 have been known in the fossil state for almost a century. They were 

 long unrecognized, however, and the earlier students who described 

 them compared them with the somewhat similar winged fruits of the 

 genus Carpinus (Betulace?e). With the botanical exploration of dis- 

 tant lands in the early part of the nineteenth century, specimens of 

 Engelhardtia began to be represented in the larger European her- 

 baria, and Baron Ettingshausen, that most sagacious of paleobota- 

 nists, as long ago as 1851 pointed out that certain supposed species of 

 Carpinus were really fruits of Engelhardtia. He returned to the sub- 

 ject in 1858 without, however, actually changing the names of any 

 of the supposed species of Carpinus nor does he seem to have been 

 aware of the existence of a living species of Engelhardtia {Oreo- 

 munnea) in Central America. 



