THE PEA TKIBE. 123 



mastered, to proceed to the second half of this long 

 letter. 



There is, perhaps, no natural order which is more 

 easily recognized than the Pea tribe, nor one in which 

 greater interest is usually taken ; it is so rich in 

 plants useful for food, as the Pea, Bean, &c. or for 

 forage, as Clover and Lucerne ; or dyes, as Indigo and 

 Logwood; or timber, as Brazilwood, Rosewood, and 

 the American Locust Trees ; or medicine, as the Senna 

 plant; or gums, as the Arabian Acacia; and attrac- 

 tive for their beauty, as Jiobinias, Laburnums, Bladder 

 Sennas, and the noble tropical species of Butea, Jonesia, 

 and Bauhinia, that it would be difficult to point out 

 any group of plants in which there is more to instruct 

 and delight the student. 



The Pea tribe is so vast that the last enumeration 

 of the species by Professor De Candolle, occupies 

 between four and five hundred closely printed octavo 

 pages. It will, therefore, be impossible for me to do 

 more than give you a sketch of the general character 

 by which this extensive assemblage is held together. 

 It consists of plants bearing pods, formed upon the 

 same plan as that of the Pea, and called Legumes ; 

 this is the great essential character, and the only one 

 which is universal. It is, therefore, necessary to 

 teach you, in the first instance, how you are to know 

 a Legume with certainty. Imagine to yourself a carpel 

 which grows long and flat, and usually contains seve- 

 ral seeds, and which, when ripe, separates into two 

 valves or halves; recollect, also, that the seeds all 

 grow to one angle only of the inside of the carpel ; 



