CLASSIFICATION OF ANGIOSPERMS. 567 



the wild strawberries the fruit is smaller, usually somewhat flesh- 

 colored and the achenes are either embedded in the torus as in F. 

 virginiana or borne on the surface as in F. vesca. The strawberry 

 fruit contains about 87 per cent, of water; 6 per cent, of cane 

 sugar; 5 per cent, of invert sugar (a mixture of dextrose and 

 levulose) ; I per cent, of free fruit-acids; and about 2 per cent, 

 of nitrogenous substances. 



g. LEGUMINOS^E OR PULSE FAMILY. The plants are 

 herbs, shrubs, trees, or vines with alternate, stipulate and usually 

 compound leaves. The flowers are complete, and the corolla is 

 either regular or irregular; the stamens are usually united, and 

 the pistil is simple and free, becoming in fruit a legume. The 

 plants are widely distributed, many of them being found in the 

 Tropics. Three principal sub-groups, which have been ranked 

 as families by some botanists, are recognized. 



1. PAPILIONAT.E. Those species with papilionaceous flowers 

 are separated into a group called the Papilidnatae. This sub-group 

 has a number of representatives in the United States, as clover, 

 locust, and Baptisia (Fig. 280, L). 



2. CESALPINIOIDE.E include the sennas and have flowers which 

 are nearly regular, or imperfectly, or not at all papilionaceous. 



3. The MIMOSOIDE^E include the acacias and have flowers that 

 are regular. 



Cassia acutifolia is a small shrub with leaves that are 8- to 

 i o- foliate. The leaflets are official as Alexandria or Tripoli senna ; 

 the flowers are yellowish and in axillary racemes; the fruit is a 

 smooth, flat, dehiscent pod, with 6 to 8 seeds. 



Cassia angustifolia is a shrub which is cultivated in Southern 

 India and resembles Cassia acutifolia. The leaflets which consti- 

 tute India senna or Tinnevelly senna are longer and narrow-lanceo- 

 late, and the pods are longer, and slightly crescent-shaped, as 

 compared to those of C. acutifolia. 



Cassia Fistula or purging cassia, the pods of which are used 

 in medicine, is a tree about 15 M. high. The leaves are 10 to 12- 

 foliate ; the flowers golden-yellow and in racemes ; and the fruit 

 is a very long, cylindrical, indehiscent legume. The leaves of 

 quite a number of species of Cassia are used in medicine and the 



