The large biennial yellow sweet clover (M. officinalis) is also called yellow melilot, balsam-flowers, heart's-clover, and king's-clover. It was introduced into this country from Europe, and grows well in waste places both in the northern and southern states. Yellow sweet clover is a biennial plant, storing in its roots the first season a reserve food supply, which is utilized in producing seed the second season. It closely resembles white sweet clover; but it has finer stems and does not grow as tall, seldom attaining a height of more than 3 to 5 feet. The flowers are yellow, in long racemes, as in the white, and bloom about two weeks earlier than those of the white species. It is thus valuable to the beekeeper, since it affords good bee pasturage earlier in the season. Nectar is secreted freely, and the honey does not differ essentially from that of white sweet clover. It is less easily exterminated, as the mower frequently passes over the decumbent stems, which thus remain to reseed the land. It is much less generally cultivated than the white species.
The small yellow annual sweet clover (M. indica), or bitter clover, grows wild in southern California and Arizona. It may easily be distinguished from the preceding species by its much smaller yellow flowers. The annual does not succeed well in other sections of the United States, and the biennial white sweet clover should be given the preference. In Ohio the annual was planted in a field which had been limed and inoculated with the proper bacteria. The seed germinated fairly well, but the plants grew so poorly that the crop was a complete failure. Melilotus indica is the only one of the sweet clovers which will make a satisfactory winter growth in southern California. It is suitable for a green-manuring crop and has been used in the citrus groves of both California and Arizona.
White sweet clover (M. alba) is also known as Bokhara clover, white melilot, bee clover, honey clover, tree clover, and honey lotus. White sweet clover was introduced into the United States by European colonists as early as 1738, but its value was not recognized to an appreciable extent until within the last 30 years. More than half of the states passed laws classing sweet clover as a noxious weed. Supervisors of roads were required in Ohio to mow it as well as Canada thistle, burdock, teasel, and other pernicious plants. Many fanners devoted a large amount of their time to endeavors to eradicate it, and there yet remain a few uninformed persons who regard it as a dangerous weed. But gradually its value became recognized, and to-day there is not an agricultural experiment station in this country that does not recognize its worth and approve of its cultivation.
White sweet clover is a biennial herb with smooth branching stems and compound leaves composed of three oblong leaflets. The first season it grows 18 to 20 inches tall and stores up in a very large tap-root reserve food, which enables the plant to make a rapid and vigorous growth the following season. The second year it grows 3 to 12 feet tall, blooms profusely, and dies after maturing its seed. The small white flowers resemble those of white clover, but are in long slender racemes instead of heads. The pod is egg-shaped, wrinkled, and contains a solitary seed. Young plants resemble alfalfa, both species belonging to the legume family; but it may readily be distinguished by the color of its bloom.
The plant has a strong odor, and the leaves a bitter taste due to cumarin. Cumarin is a vegetable substance usually obtained from the Tonka bean, hut it also occurs in sweet clover and some other plants. It is well known to physicians, and has long been used as a corrective, tonic, and antiseptic in intestinal disorders. It imparts a characteristic flavor to certain kinds of Swiss cheese. Cumarin is believed to lessen the danger of bloating in cattle, which sweet clover causes much less frequently than the true clovers and alfalfa. It is much less bitter in early spring than later in the season. Cattle may at first refuse to eat the hay, but by sprinkling it with brine this difficulty may be readily overcome.
WIDE DISTRIBUTION AND ADAPTABILITY
White sweet clover is adaptable to great extremes of climate and soil, and will produce a valuable crop of forage in sections where alfalfa and red clover will not succeed. It is as vigorous in the severe climate of Quebec, Canada, as in middle