EXPERIMENT STATION BULLETINS. 



349 



PULSE FAMILY. LEGUMINOSAE. 



In the most comprehensive sense this immense family, second in size among seed-plants, includes fully 

 7,300 species, ranking in size next to the Compositae. The family is the most remarkable of any for the 

 great number and variety of its economic plants. So far as known but few plants outside of this family 

 possess roots which furnish abodes for microbes through whose operation free nitrogen becomes available as 

 plant food. These abodes aie familiar objects on roots and are known as tubercles or nodules. Plants ol 

 greatest value are the ciovers, the alfalfas, beans, peas, lentils, lupines, vetches, cow peas, soy beans. In 

 Leguminosae are found plants of great importance for furnishing medicines, timbers, dye stufifs, gums, for 

 beauty of flowers and foliage. It furnishes a very small number of weeds. 



Fig. 116. 

 Tick-trefoil. Desmodium canadensc (L.) DC. Perennial, stem hairy, 50-150 cm. high, leaflets oblong- 

 lanceolate, obtuse, much longer than the petiole; Lowers pink, showy, 8-12 mm. long. Open woods; com- 

 mon in September, when the fruit is maturing especially annoying to sheep and cattle. A dozen or more 

 species of "tick-trefoil" are denizens of open woods, all bearing burs annoying to sheep and cattle. 



