150 LEGUMINOS^. [CLASS 



As type of the Tribe Mimoseae, principally tropical and 

 Australian, we may employ 



Broad-winged Acacia (Acacia filatypterd). 



It differs from the Pea-flower type in its regular corolla 

 with valvate aestivation, and numerous stamens. 



In a large number of Australian species of Acacia the 

 leaves are reduced to phyllodes : the blade of the leaf, 

 which is developed in some of the species, is usually very 

 much divided. 



Some species of Mimosa (especially M. pudicd) are re- 

 markable for the great degree of " irritability " exhibited 

 by the leaflets when touched or shaken. This irritability 

 is but an extreme case of a condition (called " sleep ") 

 common to many Leguminosse, the leaves of which fold 

 together in the evening, and remain closed until the next 

 morning. 



Gum Arabic is afforded by African species of Acacia. 

 It was formerly brought from Arabia or Egypt, but is 

 now chiefly imported from West Africa. Catechu, an 

 astringent used by tanners, is obtained by boiling the 

 heart- wood of A. catechu, an East Indian tree. 



The tree called Acacia, commonly planted in England, 

 does not belong to the genus Acacia. It is a North 

 American Robinia, and belongs to the Pea-flower tribe. 



22. Natural Order Rosacese. The Rose Family. 



DISTRIBUTION. Widely dispersed throughout both 

 hemispheres, though specially affecting the North Tem- 

 perate Zone. British genera 17, species 43. 



Shrubs or herbs. Flowers regular. Stamens indefinite (usually 

 4 in Alchemilla and Sanguisorba}. Pistil apocarpous (spuri- 

 ously syncarpous when the ovary is adherent). 



Type Blackberry or Bramble (Rubus fruticosus). 

 A trailing prickly shrub, with stipulate digitate leaves, 

 and panicled regular flowers. 



