The perennial, mammoth, or pea-vine red clover (var.
perenne) has less tendency to die out after the second year, is of taller and stouter growth than the common red, the flower-head somewhat stalked, the plant bearing mostly larger and darker heads , and maturing later. This is the most valuable of the cultivated red clovers. It is the plant com monly known as Trifoliusn medium, and is des ignated by Thomas Shaw as T. magnum. By some it has been considered to be the result of crossing between 2'. pratense and the true T. medium. The botanical or descriptive characters that are usually employed to separate the mammoth clover (var. perenne) from the common or medium red (T. pra tense) are of small diagnostic value. The chief dis tinction seems to lie in the perennial character, the larger size and the later maturity.
The zigzag or cow clover ( the true Trifolium medium, Linn.) seems not to be in cultivation in this country. Stems usually flexuose or zigzag ; leaflets and stipules narrow, usually elliptical, not spotted, the edges entire or slightly toothed toward the base ; heads standing one or two inches above the upper leaf, globular to oblong. There are no important and constant botanical differences be tween T. medium and the forms of T. pratense. The chief distinguishing marks of T. medium are the always more or less peduncled heads (only infre quently peduncled in T. pratense), more oblong heads with brighter-colored flowers, the narrower stipules and leaflets. The perennial form of T. pra tense, or mammoth clover, is apparently a different plant ; the name perenne has been applied to it in popular writings, but the name has no technical botanical standing.
The Orel clover (T. pratense var. foliosum, Brand) is a hairless form introduced from Russia. It " is distinguished by the dustlessness of its hay, due to almost complete absence of hairiness from all parts of the plant, by its heavy yields for the first crop, by its leafiness and the persistence of the basal leaves, by the succulence of the stems, which improves greatly the quality of the hay and reduces the waste due to woody uneatable por tions, by greater palatability than hay from domes tic seed, and by the fact that it comes to proper maturity for harvesting from ten days to two weeks later than the ordinary American red clover" [Charles J. Brand, Bulletin No. 95, Bureau of Plant
Industry, United States Department of Agriculture, 1906]. The plants are more upright than those of the common red clover and branch more freely ; the spots are sometimes absent from the leaves ; the flower-heads are smaller and less compact and tend to be more elongated.
It seems to be perennial. This new clover has been tested in a number of places in the United States and Canada with promising results. It is recom mended as a supplement to common red clover. It is thought that it may profitably supplant com mon red clover "where the best methods of man agement indicate that only one crop, either of hay or seed and a light aftermath, or some good pasturage can be advan tageously expected from clover - fields" because of its "extraordinarily heavy first crop and the free seeding capacity." The succeeding arti cles on Clover, by Smith and Wing, together with the discussion under Meadows and under Green-manures in Vol. I, will sufficiently explain the uses and culture of the red clovers.
Alsike or Swedish clover (T. hybridum, Linn.) (Fig. 335) is a tall-growing, slender-stemmed per ennial clover with small whitish or rose-colored heads ; the leaves are long-stalked, the leaflets obovate and serrulate. The alsike is readily dis tinguished from the white clover by its forking stalks (the flower-stems not rising directly from the ground) and the pinkish heads (which are usually white toward the top). One of the best of the clovers, particularly on moist and cool lands, both for pasture and hay ; also an excellent bee plant. Alsike is the name of a parish in weden.
Alsike clover is especially valuable for hay, either grown alone or in combination with grasses or with mammoth clover. It produces a very fine, soft hay that is likely to be nearly all consumed by live-stock. On well-pre pared a n d adaptable land and heavily seed ed (about fif teen pounds to the acre), it makes a dense and heavy cover two feet deep. It is very hardy and may he sown early in spring, but as the seed is small it should not be cov ered very deep. Usually, only one cutting is secured in the northern regions, where it thrives best. A good yield of seed per acre is four bushels.