This section is from the book "A Text Book Of Materia Medica, Being An Account Of The More Important Crude Drugs Of Vegetable And Animal Origin", by Henry G. Greenish. Also available from Amazon: A Text Book of Materia Medica : Being an Account of the More Important Crude Drugs of Vegetable and Animal Origin.
The marigold, Calendula officinalis, Linne (N.O. Compositoe), is commonly cultivated in numerous varieties as a garden plant. The flower head is about 5 cm. in diameter, yellow to deep reddish orange in colour, with numerous barren disc-florets and one or more rows of fertile ligulate ray-florets. The latter are collected when the flower is fully expanded and dried.
The drug consists almost entirely of the ligulate corollas of the ray-florets, about 2.5 cm. in length, enclosing in a short tube the remains of the style and two stigmas. The limb of the corolla, the tube of which is hairy externally, is terminated by three teeth, and exhibits, when examined with a lens, four principal veins. (Compare fig. 47 B).
The drug has a somewhat aromatic odour and a distinctly bitter taste.
The student should soften some calendula in water, spread the florets out, and examine them with a lens, noting
(a) The three teeth of the corolla,
(b) The four principal veins; and should compare them with the ligulate florets of arnica (which have about seven to nine veins) and of dandelion (which have five teeth). (Compare figs. 44 A, and 47 B).
Calendula contains traces of volatile oil, a bitter principle, and calendulin, the latter being a tasteless substance swelling in water (Geiger, 1818).
Calendula is used chiefly in the form of the tincture diluted with water as an application to bruises to promote the absorption of effused blood.