Mammoth clover is biennial under some conditions and under others it is perennial, although it is not usually a long-lived perennial. It has a stronger habit of growth than the medium red, and is, therefore, rather better fitted to thrive under adverse conditions, more especially when it has once obtained a hold upon the soil. It grows chiefly in the first half of the season, and makes but little growth, relatively, in the autumn, or, indeed, any time the same season after the crop has been harvested for hay. In the Northern States it comes into flower about the middle of July, and in those of the South correspondingly earlier. It is relished by all kinds of domestic animals kept upon the farm, but the hay is relatively better adapted to cows and other cattle than to horses and sheep. If cut too late, or much injured in the curing, it is too dusty for horses, and the growth is too coarse to make first-class hay for sheep. It makes excellent soiling food, because of the abundance of the growth and the considerable season during which it may be fed in the green form. It is peculiarly valuable as a fertilizer and as an improver of soils. In addition to the nitrogen which it draws from the air and deposits in the soil, it brings up plant food from the subsoil and stores it in the leaves and stems, so that when fed it can be returned to the land. It also fills the soil with an abundance of roots and rootlets. These render stiff soils more friable, and sandy soils less porous; they increase the power of all soils to hold moisture, and in their decay yield up a supply of plant food already prepared for the crops that are next grown upon the ground. Mammoth clover may also be utilized with advantage in lessening the numbers of certain noxious weeds, and in some instances of eradicating them altogether. This it does in some instances by smothering them, through the rankness of the growth. In other instances it is brought about through the setback which is given to the weeds by first pasturing the crop and then cutting it later for seed. =Distribution.=--Mammoth clover has long been grown in several of the countries of Europe and Western Asia. It is also grown in certain parts of Siberia. It was doubtless introduced into the United States from Europe by emigrants from that continent, but when exactly is not known. It has probably been many years since its introduction into America, but it is only within the more recent of the decades that it has attracted general notice. In some areas in this country it grows with great luxuriance, fully equaling, if not exceeding, the crops grown in any part of Europe. Mammoth clover calls for climatic conditions about the same as those for medium red clover. (See page 61.) It flourishes best in moist climates of moderate temperature, and it will endure more drought than the medium red variety and possibly more cold.