LEGUMINOUS PLANTS. 



13 



deplete the soil, and the same is true, in a general way, of other 

 grasses. Leguminous plants (see page 18) accumulate nitrogen 

 from the air and are of great importance as soil improvers. Clovers 

 return nitrogen to the soil, and thus to a certain degree maintain its 

 fertility. 



LEGUMINOUS PLANTS. 



Name: These plants belong to a large family of a distinct type, 

 called LeguminoscB. Peas, Vetches, Beans, Red Clover, Alsike and 

 Alfalfa belong to this great family that is, the plants which farmers 

 commonly term legumes and clovers. As generally used, the name 

 "clovers" includes Red Clover, Alsike, Dutch Clover, Crimson 

 Clover, Alfalfa, Trefoil, Sweet Clover and other leguminous plants. 

 Botanically, however, only the first four are clovers in the true sense; 

 that is, they belong to the genus Trifoluim, whereas Alfalfa, Trefoil 

 and Sweet Clover belong to other genera. 



-St 



Seed: When splitting a bean or a pea, the two halves seem 

 -to be kept together by the seedcoat only. One of them has a 



smooth, more or less shiny surface, on 

 which no special texture can be dis- 

 covered by the naked eye. Near the 

 [-- &cuf. upper end of the other half is a peculiar 

 organ consisting of two distinct portions. 

 The upper is a bud (Fig. 5, B.), which 

 (^oC. corresponds to the similar formation in 

 the grass embryo (see page 8). The 

 lower, which lies close to the seed- 

 coat, has a thicker upper part (Fig. 5, 

 St.) and a tapering end (Fig. 5, Rad.), 

 the former being the stem of the em- 

 bryo, the latter its root or radicle. By 

 far the greatest part of the seed (Fig. 5, 

 -Cot.) consists of the two cotyledons of the embryo. A leguminous 

 embryo has thus two cotyledons whereas a grass embryo has only one. 

 But a leguminous plant has no endosperm. The function of the en- 

 dosperm of a grass seed, as stated on page 8, is to supply the embryo 

 with food during germination. This function in a leguminous plant is 

 performed by the two cotyledons, which are thick and filled with food. 



Fig. 5. Section through a Bean. 



Four times natural size. 



B. Bud. Rad Radicle. 



St. Stem. Cot. Cotyledon. 



Germination : When the seed of a leguminous plant germinates, 

 the bud (Fig. 5, B.) develops into stem and leaves and the radicle 

 (Fig. 5, Rad.) into the root of the plant. The stem of the embryo 



