MEDICAGO, SNAIL-TREFOIL, in botany: A genus of the decandria order, belonging to the diadelphia class of plants; and in the natural method ranking under the 32d order, Papilionaceæ. The legumen is compressed and scrawed; the carina of the corolla luring down from the vexillum. There are nine species, though only five are commonly cultivated in this country. They are low trailing plants, adorned with small yellow flowers, succeeded by small, round, snail-shaped fruit, which are downy, and armed with a few short spines. They are all easily propagated by seeds. For the properties and culture of LUCERN, a species of this genus, see AGRICULTURE, n° 183.