TRIBULUS, CALTROPIS; a genus of the monogynia order, belonging to the decandria class of plants. There are three species; the most remarkable is the terrestris, with six pair of lobes to each leaf. It is a very common weed in the south of France, in Spain, and Italy, where it grows among corn, and on most of the arable land, and is very troublesome to the feet of cattle; for the fruit being armed with strong prickles, run into the feet of the cattle which walk over the land. This is certainly the plant which is mentioned in Virgil's Georgics under the name of tribulus, tho' most of his commentators have applied it to other plants. It is called in English caltrops, from the form of the fruit, which resembles those instruments of war that were cast in the enemies way to annoy their horses.—This hath a slender fibrous root, from which spring out four or five slender hairy stalks, which spread flat on the ground, garnished at each joint with winged leaves, composed of six pair of narrow hairy lobes, almost of equal size; those on the lower part of the stalk stand alternately, but toward the top they are placed opposite. The flowers come out from the wings of the stalk, standing upon short footstalks; they are composed
composed of five broad, obtuse, yellow petals, which spread open. In the centre is situated an oblong germin, crowned by a headed stigma, attended by ten short stamens, terminated by single summits, and are succeeded by roundish, five-cornered, prickly fruit, which, when ripe, divides into five parts, each having a transverse cell containing one or two seeds.—This plant is preserved in botanic gardens for variety. It is propagated by seeds, which should be sown in autumn; for those which are kept out of the ground till spring commonly remain in the ground a whole year before the plants come up. These seeds should be sown on an open bed of light earth, where they are designed to remain; for as it is an annual plant, it doth not bear transplanting very well, unless it be done when the plants are very young. In the spring, when the plants come up, they should be carefully cleared from weeds; and where they come up too close, some of the plants should be pulled out to give room for the remaining plants to grow; after this they will require no other culture but to keep them clear from weeds. If the seeds are permitted to scatter, the plants will come up the following spring, and maintain their place if they are not overborne with weeds.