arrow-head: A genus of the polyandra order, belonging to the monococcia clas of plants; and in the natural method ranking under the fifth order, Tripetaloidae. The male calyx is triphyllous; the corolla tripetalous; the filaments generally about 14; the female calyx is triphyllous; the corolla tripetalous; many pistils; and many naked seeds. There are four species, of which the most remarkable is the sagittifolia, growing naturally in many parts of England. The root is composed of many strong fibres, which strike into the mud; the footstalks of the leaves are in length proportionable to the depth of the water in which they grow; so they are sometimes almost a yard long; they are thick and fungous; the leaves, which float upon the water, are shaped like the point of an arrow, the two ears at their base spreading wide astern, and are very sharp-pointed. The flowers are produced upon long stalks which rise above the leaves, standing in whorls round them at the joints. They consist of three broad white petals, with a cluster of stamens in the middle, which have purple summits. There is always a bulb at the lower part of the root, growing in the solid earth beneath the mud. This bulb constitutes a considerable part of the food of the Chinese; and upon that account they cultivate it. Horses, goats, and swine, eat it; cows are not fond of it.