366 E. C. ANDREWS. 
Hedysareze. On the other hand a study of the seedlings 
of legumes suggests that the Mimosez are relatively young 
as compared with genera such as Cassia, Crotalaria, Rhyn- 
chosia, Psoralea, Dalbergia, Bauhinia, and Sophora. Still 
again, however, from a study of seedlings and from a study of 
allied families such as Rosacee, Connaracee, Saxifragacez, 
Passifloraceze, and Crassulacez, it is evident that the 
Papilionacee are extremely modified plant types, and that 
free stamens and regular corollas characterised the more 
primitive types of the order. To this point reference will 
be made subsequently. 
Itis not here maintained that Mimosez and Oczesalpinieze 
are older than Papilionacez, but on the other hand, it 
would be unscientific to assume that the Papilionacez are 
the older forms simply because the Mimosez and Cesal- 
pinieze belong to the tropics, rather than to the temperate 
regions, and because the Papilionacez have spread from 
the tropics into the temperate regions. 
In many genera there is a tendency to become fixed 
under peculiar conditions, while for certain elastic types a 
new geographical environment presents them with the 
opportunity to develop into new genera and species with 
great relative rapidity. A hasty consideration of Sophorez 
would suggest its youth as compared with that of Poda- 
lyriez, nevertheless, as may be shown later, the former 
appears to be an old, decadent tribe, while the latter is a 
vigorous offshoot from this vanishing tribe. Indeed, the 
geographical distribution and the morphology of Leguminosze 
and Myrtacee suggest that small genera sporadically dis- 
tributed over wide areas are decadent types, while local 
floras of peculiar type with large genera and numerous 
individuals are relatively young. | 
An example of this may be seen in the infrequent mem- 
bers of Dalbergia, Sophora, and other types, confined to 
