Urocystis
(from oura, a tail or stalk, and kystis, a vessel or bladder; in allusion to the stalked, vesicular spores). This is one of the genera included in the group of Fungi known to botanists as the Ustilaginei, and in popular language as Smuts, from their loose, dark spores giving a dirty appearance to the plants in which they grow. The Fungi in this genus are parasites; they grow for a while inclosed in the tissues of living plants; then, when the spores ripen, they form dark swellings, whose growth bursts the outer tissues of the host-plant, and discloses the powdery mass of spores. The parts in which these are formed are usually much swollen and distorted. The spores of Urocystis vary a good deal in size and form, but usually consist of a layer of rather small cells, surrounding a larger central cell, which is the one actively concerned in the development of new mycelium when the spore is kept in a warm, moist atmosphere. The spores are fixed on the tips of branches till ripe, when they fall from the stalks. The species of Urocystis are hurtful to cultivated plants, and the following occur in Britain: U. Violae grows in petioles and other organs of the Sweet Violet (Viola odorata); U. Anemones is very common on various kinds of Anemone, and on allied plants; and U. sorosporioides occurs on leaves and flowers of Thalictrum. For remedies, see Ustilago.