Essential-Oil Ducts

receptacles of essential oils in various plant organs. Essential-oil ducts form as a result of the cell separation (schizogonous ducts, primarily in St. John’s wort and umbellifers), cell dissolution (lysogenic ducts, for example, in dittany and citrus fruits), or mixed causes (in some Rutaceae). Sometimes the essential oil accumulates in separate cells (idioblasts, for example, in hairgrass, laurel, and camphor tree) or in glandular filaments (chiefly in Labiatiae).