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 

 Legtiminosm and 

 the common name 

 "Legumes." 



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

 nus), clover [Trifoiium), locust {Robinia), Wistaria, pea 

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

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

 {<rleditschia), indigo {Indigofera), sensitive-plants {Acacia, 

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



Fig. SSL 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. 



