474 



DICOTYLEDON ES. 



frame, but the intermediate portion divides, as in the transversely 

 divided siliqna, into as many nut-like portions as there are seeds. 

 Some species have a pod of enormous dimensions. The seeds of 

 Entada gigalobium are often carried from the West Indies to the 

 "N. W. coasts of Europe by the Grulf Stream. The fruit of Acacia 

 in some species is an ordinary pod, in others it is transversely 

 divided, or remains an undivided fruit, a nut. This order includes 



FIG. 514. Acacia farnesianu. : a inflorescence ; b flower. 



both trees and herbaceous plants, which are often thorny; the 

 leaves are usually bipinnate (Fig. 514) and are sensitive, and also 

 possess sleep-movements. Many Australian Acacias have com- 

 pound leaves only when young, but when old have phyllodia, i.e. 

 leaf-like petioles without blades, placed vertically. A large number 

 have thorny stipules, which in some (Acacia sphcerocephala) attain 

 an enormous size, and serve as a home for ants, which in return 

 protect their host- plant against the attacks of other, leaf -cutting 

 ants. 



