136 



FAMILIES OF FLOWERING PLANTS 



liisceut (not splitting open) at maturity, is one-seeded, and structurally 

 a pod. Tlie genus was formerly placed with the Polj^galaceae, and by 

 many authors is now regarded as a distinct family. 



Family Papilionaceae. Pea Family. This, the typical group of 

 the Leguminosae, is at the same time the largest and most important 

 family of the Order Resales, The plants range in size from the small- 

 est of herbs to the loftiest of forest trees, and are comprised in about 

 310 genera and 5000 species, most abundant in tropical and subtropical 

 regions, though some extend to the Arctic zone. The character from 



From Coulter's Plant Structures. Copyright, 1900, D. Appleton & Co. 

 Fig. 119. A leguminous plant {Lotus) showing flowering branch; (i), detached flower; (2), clus- 

 ters of 10 .stamens; (3), single carpel; (4), fruit, a pod; (5), petals dissected apart; (6), consisting of 

 standard {a); wings {b); and keel (c); and floral diagram (7). After Wossidlo. 



which the family takes its name is found in the peculiar and very irreg- 

 ular shape of the flower (see Fig. 119). The upper petal, usually the 

 largest, is known as the banner or standard; the two lateral are called 

 wings, and the lowermost or forward pair jointly form the keel, which 

 usually closely enfolds and protects the stamens and pistil. The lat- 

 ter is 1-celled, forming a pod in fruit. The stamens are usually 10, and 

 may be distinct, diadelphous (united into two sets by their filaments, 

 or monadelphous (similarly united into a single set). 



The papilionaceous flower, as it is usually called, is in most of the 

 genera identifiable at sight, but there are some exceptions; thus in 

 A)norpha the corolla consists of only one petal, the standard, which is 

 folded over the pistil like the keel in an ordinary flower. So also the 



