PRINCIPLES OF CLASSIFICATION. 



13 



which are used as ornamental climbers. The species is of little prac- 

 tical value except for the fact that the seeds are used to a small extent 

 in the Tropics as food for man. 



PRINCIPLES OF CLASSIFICATION. 



Garden beans naturally divide themselves primarily into the five 

 species of which American bean varieties consist. So far there have 

 been no hybrids between the different species of garden beans, and 

 all garden varieties belong unquestionably to one or the other of 

 these five species. Two of these, the Vicia faba, or English Broad 

 bean, represented in this country by about 10 distinct varieties, and 

 the Vigna sesquipedalis, or Asparagus bean, represented in this coun- 

 try by one distinct variety, contain so few contrasting types that 

 they are not separated into classes, but the remaining 3 species are 

 very readily classified. 



Phaseolus vulgaris, the Kidney bean, represented in this country 

 by 145 distinct varieties, has often been separated by botanists and 

 horticulturists, principally on the color and shape of the seed. The 

 objection to such a classification or to any classification based chiefly 

 or wholly on a single character is that it often separates varieties 

 which are very similar or identical in other respects and brings 

 together sorts which are very different in habit of vine or other qual- 

 ities. The best classification for Kidney beans seems to be as fol- 

 lows: (1) Into pole and bush, (2) into green-podded and wax-podded, 



(3) into different degrees of brittleness or toughness of pods, and 



(4) into various other divisions and subdivisions, based upon habit of 

 vine, shape of pod, color of seed, or on some other quality peculiar 

 to each subdivision, these final distinctions depending, as pointed out 

 in the classification on page 29, upon the quality which best brings 

 together identical or similar varieties. Such a classification separates 

 most of the field from the garden varieties, most of the horticultural 

 class from those not known as horticultural, most of the Red Valen- 

 tine class from other varieties, and makes various other characteristic 

 and useful divisions. 



L^Jiaseolus lunatus, the Lima bean, is also separated primarily into 

 pole and bush. In this species the shape of the seed is so very charac- 

 teristic that both the pole and bush varieties may be divided upon 

 this character as follows: (1) Into flat, large-seeded sorts typifying 

 large, wide, somewhat flat pods with large but not glossy leaf; (2) into 

 flat, small-seeded sorts typifying small, very flat pods with small, 

 glossy leaf; and (3) into thick, large-seeded sorts typifying thick-seeded 

 rather than large, flat-seeded sorts, and large dull rather than small 

 glossy leaves. Other than these divisions, there is no further classi- 

 fication of Limas which has any significance among American sorts. 



109 



