=HISTORY AND ADAPTATIONS.= Crimson clover is a native of Europe, where it is cultivated as a forage and green-manuring crop in Italy, France, Spain, Germany, Austria, and Great Britain. Large quantities of crimson-clover seed are exported from Europe to the United States, especially from the districts of central France, where crimson clover is the premier leguminous forage plant. Crimson clover was introduced into this country as early as 1818, and the seed was widely distributed by the United States Patent Office in 1855. The plant was at first regarded more for its ornamental value than as a forage plant, however, and it was not until about 1880 that its value for agricultural purposes began to be appreciated. [Illustration: Fig. 2.--Map of a part of the United States, showing the region where crimson clover is most widely grown.] At present crimson clover is grown most widely in the lighter sandy areas of the Atlantic Coastal Plain, where the soil is not very rich and the winters are not severe. (Fig. 2.) The plant does not withstand either extreme cold or extreme heat, and its culture is therefore limited to regions which enjoy at some time during the year a long period of relatively mild, moist weather. Ordinarily, this clover does not survive the winter in latitudes north of southern Pennsylvania, while in some of the Southern States it is frequently killed by dry, hot weather in the fall or spring. It succeeds well in the humid regions near the Gulf of Mexico and in the Pacific Northwest, but in these areas it is not widely grown. Normally, crimson clover is a winter annual comparable to winter wheat; that is, it is planted in the fall, lies more or less dormant over winter, grows rapidly in the spring, and dies, after going to seed, early in the summer. Where the summers are not too hot it can be planted in the spring and grown as a summer crop, but for this purpose other clovers are usually preferred. =VARIETIES.= Crimson clover is exceedingly variable both in color of flower and in time of maturity. These variations are particularly noticeable in fields planted from a mixed lot of seed, the flowers presenting a range in color from nearly pure white to a deep purplish red and the seeds a difference in date of ripening of more than a month. Since crimson clover is thought to be mainly self-pollinated, it is easy to fix these qualities by selection and to establish definite varieties.