The tribulus[2217] grows nowhere except in marshy places: though held in abomination elsewhere,[2218] it is employed on the banks of the Nilus and Strymon as an article of food. It always bends towards the water, and has a leaf like that of the elm, with a long stalk. In other parts of the world there are two varieties of this plant; the one[2219] with leaves like those of the chicheling vetch, the other with leaves protected by prickles. This last variety blossoms also at a later period than the other, and is mostly found in the hedge-rows about farm-houses. The seed of it is black, rounder than that of the other, and enclosed in pods: that of the other variety bears a resemblance to sand. Among the prickly plants there is also another kind, known as the “anonis:”[2220] indeed, it has thorns upon the branches, to which leaves are attached similar to those of rue, the stem being entirely covered also with leaves, in form resembling a garland. It comes up in land that has been newly ploughed, being highly prejudicial to the corn, and long-lived in the extreme. CHAP. 59.—PLANTS CLASSIFIED ACCORDING TO THEIR STEMS: THE CORONOPUS, THE ANCHUSA, THE ANTHEMIS, THE PHYLLANTHES, THE CREPIS, AND THE LOTUS. Some, again, among the prickly plants have a stem which creeps along the ground, that, for instance, known as the “coronopus.”[2221] On the other hand, the anchusa,[2222] the root of which is employed for dyeing wood and wax, has an upright stem; which is the case also with some of the plants that are prickly in a less degree, the anthemis,[2223] for example, the phyllanthes,[2224] the anemone, and the aphace:[2225] the crepis,[2226] again, and the lotus,[2227] have a foliated stem. CHAP. 60.—PLANTS CLASSIFIED ACCORDING TO THEIR LEAVES. PLANTS WHICH NEVER LOSE THEIR LEAVES: PLANTS WHICH BLOSSOM A LITTLE AT A TIME: THE HELIOTROPIUM AND THE ADIANTUM, THE REMEDIES DERIVED FROM WHICH WILL BE MENTIONED IN THE FOLLOWING BOOK. The leaves of plants, as well as those of trees, differ from one another in the length of the footstalk, and in the breadth or narrowness of the leaf, and the angles and indentations perceptible on its edge. Other differences are also constituted in respect of their smell and blossom. The blossom remains on longer in some of those plants which flower only a little at a time, such as the ocimum,[2228] the heliotropium,[2229] the aphace, and the onochilis,[2230] for example. (17.) Many of these plants, the same as certain among the trees, never lose their leaves, the heliotropium,[2231] the adiantum[2232] and the polium,[2233] for instance. CHAP. 61.—THE VARIOUS KINDS OF EARED PLANTS: THE STANYOPS; THE ALOPECUROS; THE STELEPHUROS, ORTYX, OR PLANTAGO; THE THRYALLIS.