Cydo'nia (Py'rus) Cydonia, Quince. -- Pomaceae. The seed; U.S.P. 1850-1880; W. Asia. Tree 2.5-6 M. (8-20 degrees) high, with crooked, straggling branches; leaves like pear leaves; flowers white or purplish; fruit pear-shaped; seed 6 Mm. (1/4') long, ovate, triangular, brown, covered with whitish, mucilaginous, epithelium causing seed of each cell to adhere; swell with water, forming heavy mucilage; 2 cotyledons, white, oily, bitter-almond taste; very similar to apple seed. Contain mucilage (cydonin) 20 p.c. (not precipitated by borax or potassium silicate, soluble in cold and hot water), fixed oil, proteins; used as demulcent, protective; fruit astringent. Mucilago Cydonii (1 part + water 50), U.S.P. 1880; may use rose water, or camphor water--externally.