The roots are harvested at the end of the first year's growth in order to secure the most acceptable drug and also to prevent the plants from bearing seed and spreading as a weed. The tops of the plants may be cut with a mower and raked off, after which the roots can usually be turned out with a deep-running plow or with a beet lifter. In a dry and very sandy soil the roots frequently extend to a depth of 2 or 3 feet, making it necessary to dig them by hand. After digging, any remaining tops are removed and the roots are washed and dried, the drying being preferably by the use of low artificial heat. The roots are usually split lengthwise into two or more pieces in order to facilitate drying, although whole roots are marketable. Yields at the rate of 1,500 to 2,000 pounds of dry roots per acre have been obtained. The prewar prices offered by dealers ranged from 4 to 6 cents a pound. The prices for the root and seed in June, 1920, were 12 cents a pound each. CALAMUS. Calamus, or sweet flag (_Acorus calamus_), is a native perennial plant, occurring frequently along streams and in the edges of swamps throughout the eastern half of the United States. The dried root (rhizome or rootstock) is the part used as a drug. Although calamus in a wild state is usually found growing in water, it may be cultivated in almost any good soil which is fairly moist. It usually does well on moderately dry upland soils which will produce fair crops of corn or potatoes. The plants are readily propagated from divisions of old roots, which should be set early in the fall 1 foot apart in rows and well covered. During the following growing season the plants should receive frequent and thorough cultivation. The roots are harvested in the fall and may be readily dug with a spade or turned out with a plow. The tops, together with about an inch of the rootstock, are next cut off and used to make new plantings. The roots are washed and dried artificially at a moderately low degree of heat. The marketable product consists of the thick rootstocks deprived of their small rootlets often called "fibers." These may be removed before drying, but more easily afterwards, since when dry and brittle they break off readily with a little handling. Roots thus treated are often called "stripped" and are more aromatic than those which have been peeled. Yields at the rate of 2,000 pounds of dry roots per acre have been obtained. The prewar price for the unpeeled root usually ranged from 3 to 5 cents a pound. The prices in June, 1920, were 10 to 12 cents a pound. The annual importation of calamus root ranges from 5 to 10 tons. CALENDULA. Calendula, or pot marigold (_Calendula officinalis_), is a hardy annual plant native to southern Europe, but frequently grown in flower gardens in this country. The dried flower heads are sometimes used in soups and stews, and the so-called petals (ligulate florets) are employed in medicine.