Calendula. N. F. IV. (U. S. VIII.) Marigold. Mary-bud. Holligold. Flours de Tous les mois, Souci, Fr. Ringelbume, Todtenblume. Gold-blumen, G. Calendula, Sp.—"The dried ligulate florets of Calendula officinalis Linne (Fam. Compositae), without the presence of more than 2 per cent. of other parts of the plant or other foreign matter." N. F.
The N. F. drug is described as in "florets from 15 to 25 mm. in length, yellow- or orange-colored, one to three-toothed, four- to five-veined, margin nearly entire, the short hairy tube occasionally enclosing the remnants of a filiform style and bifid stigma. Odor slight, somewhat heavy; taste slightly bitter, faintly saline. The powdered drug is light yellow to orange-yellow and, when examined under the microscope, exhibits a few characteristic, non-glandular hairs, consisting of a double row of thin-walled, more or less collapsed cells, with a one- or two-celled summit, and up to about 0.8 mm. in length; elongated epidermal cells with thin, somewhat wavy walls, a striated surface, and containing irregular chromoplasts and oil-like globules, the latter coalescing when mounted in hydrated chloral T.S.; pollen grains, more or less spherical, with numerous spiniae projections, three pored, and up to 0.04 mm. in diameter; tracheae about 0.009 mm. in width with spiral and annular markings; prisms or rosette aggregates of calcium oxalate from 0.002 to 0.004 mm. in diameter. Calendula yields not more than 11 per cent. of ash." N. F. The odor is much stronger in the fresh than in the dry flowers, and on exposure to light, the orange-red or yellow color fades. Among its constituents are a bitter principle, and an amorphous substance called calendulin (discovered by Geiger most abundantly in the flowers), considered by Berzelius as analogous to bassorin, though soluble in alcohol. French or African Marigold, so called, is very frequently substituted for the official drug. It is the Tagetes patula L., and T. erecta Linn., both of Mexico. The flowers are readily distinguished by the scales of the involucre being united to form a tube, and by the slender, flattish achenes being crowned with a few chaffy or awned scales. The broadly strap-shaped ray-florets are toothed, and of a light or deep orange color sometimes striped with red. Latour and Magnier de la Source isolated from African marigold a yellow crystalline substance, quercetagetin, which Perkin examined and gave the composition C15H10O8. (P. J., 1902, 294.)
In the days of therapeutic darkness calendula was thought to be medicinally active, but it has no virtues beyond that of a feeble aromatic. Both the leaves and the flowers were used; but the latter were preferred, and were usually administered in the recent state in the form of tea. Dose, from fifteen to sixty grains (0.9-3.9 Gm.) See Tinctura Calendulae, N. F. (Part III).