FAMILIES OF FLOWERING PLANTS 139 
perfumers in the manufacture of sachet powders and other perfumes. 
The odor is due to a principle known as cowmarin. 
Tribe Viceae. From the economic standpoint this and the follow- 
ing are the most important groups of the Papilionaceae. The genus 
Pisum comprises all forms and varieties of the cultivated pea, while the 
Fig. 122. Hairy vetch, Vicia villosa, showing also enlarged flower, column of stamens and pod. 
After Tracy, Bull. No. 15, Div. of Agrost. U. S. Dep. Agric. 
fragrant sweet pea belongs to the genus Lathyrus, of which there are 
many wild species. Vicia, a closely related genus, includes the wild 
vetches and tares, so troublesome in grain fields, but it also contains 
the hairy vetch (V. villosa), an important forage, plant of the southern 
States (see Fig. 122). The European genus Lens furnishes the lentil, 
while Cicer is the gram or chick pea. 
