[Illustration: Fig. 6.--Outline map of the United States, showing the localities where sweet clover is grown for forage or for green-manure. Each dot or circle indicates a county where 50 acres or more is grown under cultivation. The solid dots represent white or yellow sweet clover; the circles represent annual yellow sweet clover.] At the present time sweet clover is grown rather extensively as a field crop in the limestone regions of Alabama, Mississippi, and Kentucky, in northern Illinois, and throughout the western North-Central and Mountain States (fig. 6): in fact, it is grown as a cultivated crop to some extent in nearly every State in the Union. Comparatively little sweet-clover seed is sown in the Atlantic Coast States, since there the soils are for the most part acid, and heavy applications of lime will be necessary before sweet clover can be grown successfully. It is questionable whether this plant will ever be of much importance in the South Atlantic States, as cowpeas, soy beans, and crimson clover will make a fair growth on those soils in their present condition. The acreage of sweet clover probably will increase in the New England States, where it should prove of value as pasturage and as a soil-improving crop on soils where red clover no longer can be grown. Sweet clover grows abundantly in the limestone regions of northwestern New York. A much larger acreage of sweet clover is grown in northern Illinois than in any other of the eastern North-Central States. The conditions in the western North-Central States and in the Mountain States appear to be particularly adapted to this crop. It is in that part of the country that the largest acreage is found, and, with the exception of the limestone regions of the South, that the least difficulty is experienced in obtaining a stand. In those parts of the Mountain and Pacific Coast States, especially Utah, where it has not been tested carefully or where red clover or alfalfa can be grown successfully, sweet clover is looked upon as a weed. It may rightly be considered a weed in the irrigated regions of the West and Northwest, where it grows luxuriantly on ditch Banks. The dissemination of this plant in all parts of the country has been hastened by beekeepers who have seeded it in waste places for the production of honey. CLIMATIC ADAPTATIONS.