Species of Trifolium (Leguminosae), particularly those that are useful in agriculture. The word is also applied to species of related genera, as Medicago. The sweet clover is Melilotus. Bush and Japan clover are Lespedezas. Prairie clover is a Petalostemon.

About 300 species of Trifolium have been described. These are widely dispersed in temperate climates. The flowers are papilionaceous but small, and are disposed in dense heads or spikes. The leaves are digitately or palmately 3-foliolate. The common European red clover is T. pratense, Linn., now thoroughly naturalized in North America, but supposed not to be native here. It is valuable both for stock feed (as pasturage and hay), and also as a green manure. As a manure crop, to be plowed under, it is particularly useful because of its deep root-system and its power (in common with other leguminous plants) of fixing the nitrogen of the air by means of its roots. Fig. 1001 illustrates the root system. Fig. 1002 shows the root of a fifteen-months-old plant that grew in hard clay soil. It is 22 inches long, and some of the root was left in the ground. The mammoth red clover (T. medium, Linn.) is perhaps an offshoot of T. pratense. It is usually a larger plant, with zigzag stem, entire and spotted leaflets, and longer-stalked head.

White clover, or shamrock, is T. repens,

Trifolium pratense. Root system.

Fig. 1001. Trifolium pratense. Root-system.

Linn., introduced from Europe, and supposed to be native to North America as well. Alsike clover, T. hybridum, Linn., is of

Old World nativity. The crimson or scarlet clover (T. incarnatum, Linn.), Fig. 1003, an annual from southern Europe, is now much grown as a catch- or cover-crop in orchards. See Cover-crops. It is also highly ornamental, and is worthy the attention of the florist. For agricultural discussion of the clovers, see Vol. II, Cyclo. Amer. Agric. l. H. B.

The penetrating root of the red clover.

Fig. 1002. The penetrating root of the red clover.

Crimson clover.   Trifolium incarnatum. (X 1/3)

Fig. 1003. Crimson clover. - Trifolium incarnatum. (X 1/3)

Cloves

Cloves are the dried flower-buds (Fig. 1004) of a handsome tree of the myrtle family Jambosa Caryophyllus or Eugenia caryo-phyllata, better known as Caryophyllus aroma-ticus, a native of the Spice Islands, but now cultivated in the West Indies and elsewhere. See Eugenia. Caryophyllus, the ancient name of the clove, means "nut-leaf." The carnation, or "clove pink, "was named Dianthus Caryophyllus because of its clove-like odor, and it has become the type of the great order Caryophyllaceae, which, however, is far removed botanically from the Myrtaceae. The word "gilliflower" is a corruption of caryophyllus, and, until Shakespeare's time and after, was applied to the carnation, but now-a-days it usually refers to certain cruciferous plants of the genera Cheiranthus and Matthiola.

Clove. 1. Spray of leaves and flowers; 2. The expanded flower; 3. An unopened bud, or clove.

Fig. 1004. Clove. 1. Spray of leaves and flowers; 2. The expanded flower; 3. An unopened bud, or clove.

The clove bark of pharmacy is secured from Dicy-pellium caryophyllatum, of Brazil, one of the Lauraceae.

The word clove is used among gardeners for a small secondary bulb employed for propagating, specially for the little bulb that forms in a scale-axil of a larger bulb.