PLANTS. 259 



pinnate, leaflets numerous, small, oblong, five to seven 

 pairs ; it is a high tree, trunk one foot in diameter, bark 

 black, branches armed with numerous thorns. Flowers 

 bloom in small clusters ; pods six inches long, and filled 

 with brown seeds. The sap, which abounds in this tree, 

 and exudes from the bark as the gum from the common 

 cherry furnishes the well known Gum Arabic of the 

 shops. It is the type of all gums ; many species of 

 acacia, as well as the plum and cherry yield it. Used 

 in Europe and America partly for medicinal, and partly 

 for various other purposes. In Arabia, Egypt, and 

 Senegal, where the tree is native, the inhabitants use 

 it as food. h. 



The Sensitive Plant (Mimosa pudica) has a stem 

 clothed with prickles and bristles ; leaves twice pinnate 

 and digitate ; leaflets small, linear, and of many pairs ; 

 seldom reaches above two or four feet in height; stalk 

 reddish colored, with crooked thorns. If the leaves are 

 even slightly touched they suddenly shrink, and, together 

 with the branch, bend downward to the earth. A native 

 of South America, but cultivated in the conservatories 

 of Europe, if. 



TWENTY-SEVENTH FAMILY. ROSACEJE or ROSE GE- 

 NUS. (Class 13, L.) Are plants with regular flowers, 

 numerous distinct stamens inserted on the calyx, and 

 1. with many pistils, which are quite distinct, or (in 

 the Pear Tribe} united and combined with the calyx 

 tube. Seeds few, and without albumen. Leaves alter- 

 nate, and with stipules at the base of leaf. 



The Almond Tree (Amygdalis communis) much re- 

 sembles a peach tree. The calyx is campanulate, five cleft, 

 and colored ; with five petals. The flowers solitary or 

 in pairs, mostly alone, and of a beautiful rose color. 



