1187. These plants are not absolutely to be depended on, however, even in Britain; and in other countries they are sometimes found in soils directly opposite. Still, the cultivated saintfoin (Onobrychis sativa) is almost always an indication of a calcareous soil; the common colt's foot (Tussilago Farfara), of blue clay; the red sandwort (Arenaria rubra), of poor sand; and the sheep's sorrel (Rumex Acetosella), of the presence of iron, or of peat. The common reed (Phragmites communis) and the amphibious polygonum (Polygonum amphibium) grow on alluvial soils, which yield excellent crops if properly drained; but where the corn horse-tail (Equisetum arvense) grows freely, it indicates a cold and retentive subsoil. The corn-field pimpernel (Anagallis arvensis), the corn-field madder (Sherardia arvensis), the corn-field gromwell (Lithospermum arvense), and the salad lamb's lettuce (Valerianella olitoria), grow on cultivated lands, where the soil is a strong black loam on a dry bottom; when such a soil is wet, the clown's all-heal (Stachys palustris) makes its appearance. A light sandy soil is known by the presence of the purple archangel (Lamium purpureum); the shepherd's purse (Capsella bursa pastoris). If the parsley piert (Alchemilla A'phanes) is found, the soil is rather unproductive; if the corn-field spurrey (Spergula arvensis) grows very thick, the ground has likely been rendered too fine by the harrow; the common ragwort (Scnecio Jacob£'a), and the corn-field cirsium (Cirsium arvense), grow indiscriminately on light and strong loams, but always indicate a fertile soil. The vernal draba (Draba verna) and the annual knawel (Seleranthus annuus) grow on soils that are dry, sandy, and poor in the extreme. The spiny rest-harrow (Ononis spinosa) is often found on dry pasture, and where the soil is incumbent on rotten rock. The aquatic, peaty, and saline soils are almost every where indicated by their appropriate plants; a proof, as we have before stated, that the climate and natural irrigation of plants have much more influence on their habits than mere soil. (Galpine's Compendium; Flora Brit.; Loudan's Hortus Brit; Kent's Hints; Farmer's Mag. Feb. 1819; and the Quarterly Journal of Agric. for Aug. 1828.)
