MONOCOTYLEDONS AND DICOTYLEDONS 



265 



(Fig. 250). The petals are very dissimilar, the upper one 

 (standard) being the largest, and erect or spreading, the two 

 lateral ones (wings) oblique and descending, the two lower 

 ones coherent by their edges to form a projecting boat-shaped 

 body (keel), which 

 incloses the sta- 

 mens and pistil. 

 From a fancied re- 

 semblance to a but- 

 terfly such flowers 

 are said to be papil- 

 ionaceous. 



The whole fam- 

 ily is further char- 

 acterized by the sin- 

 gle carpel, which 

 after fertilization 

 develops a pod 

 (Fig. 250, 5), which 

 often becomes re- 

 markably large as 

 compared with the 

 carpel. It is this 

 peculiar pod (le- 

 gume) which has 

 given to the family 

 its technical name 

 Leguminosm and 

 the common name 

 "Legumes." 



Well-known members of the family are lupine (Lupi- 

 nus), clover (Trifolium), locust (Kobinia), Wistaria, pea 

 (Pisum), bean (Phaseolus), tragacanth (Astragalus), vetch 

 (Vicia), redbud (Cercis), senna (Cassia), honey-locust 

 (Oleditschia) , indigo (Indigofera), sensitive-plants (Acacia, 

 Mimosa, etc.) (Fig. 251), etc, 



FIG. 251. A sensitive-plant (Acacia), showing the 

 flowers with inconspicuous petals and very nu- 

 merous stamens, and the pinnately branched sen- 

 sitive leaves. After METER and SCHUMANN. 



