The common 'parsley, which is used extensively as a culinary herb, is a hardy biennial bearing pinnately-compound leaves which in the cultivated varieties are greatly divided. During its early stages the leaves are arranged in rosettes and the plant is six inches or less above the ground; the flowering and fruiting plant, however, is from 2 to 3 feet in height. It is a native of Sardinia and was introduced into England in 1548, and is naturalized in salt marshes on the coast of California.

It has been cultivated as a sweet herb since earliest times and was used by the ancient Greeks and Romans as a part of their festive garlands on account of retaining its color so long.

Both the root and the fruit of parsley have been used in medicine. The fruit, often incorrectly called parsley seeds, consists of two dried mericarps which in the fresh state are joined along the center commissure. The U. S. P. IX described them as follows: " Mericarps usually separated, ovoid-crescent shaped, from 2 to 3 mm. in length and about 1 mm. in diameter; externally grayish-brown, becoming grayish or brownish on aging, having 5 yellowish, filiform, prominent ribs, alternating with the coarsely roughened furrows; in transverse section nearly hemispherical, the commissural surface with 2 vittae or oil-tubes, the dorsal surface usually with a single vitta, occasionally 2 vittae in the grooves between the primary ribs; endosperm large, oily, enclosing a small embryo; odor and taste characteristic and aromatic, especially when bruised. Under the microscope, sections of Parsley Fruit show an epidermal layer with thick cuticularized walls having numerous small centrifugal projections; several layers small thin-walled parenchyma cells, being usually considerably collapsed and occasionally containing a rosette aggregate of calcium oxalate; a single, large, brown, elliptical vitta or oil-tube between each of the primary ribs and surrounded by a layer of comparatively large yellowish-brown,, tangentially elongated cells; a singe fibro vascular bundle more or less surrounded by a few or occasionally numerous sclerenchymatous fibers; inner epidermis of narrow, thin-walled elongated cells closely cohering with the brownish tabular cells of the seed-coat; commissural surface usually with 2 large vittse, a very few stone cells and showing a slight separation of pericarp and seed-coat; endosperm of polygonal, thick-walled parenchyma cells containing fixed oil and numerous, small aleurone grains, usually containing a small rosette aggregate of calcium oxalate.

The vittae usually contain yellowish oil globules or a resin-like mass adhering to the walls, and occasionally are divided by a radial wall. The powder is grayish-brown; mostly of large, irregular fragments; cells of endosperm with aleurone grains, each usually containing a rosette aggregate of calcium oxalate, from 0.003 to 0.007 mm. in diameter; fragments with light yellow vittse and the yellowish-brown cells of the pericarp; fragments with narrow tracheae and more or less lignified sclerenchymatous fibers." U. S. IX.

Parsley root (Petroselini Radix, N.F. IV) was described as " The entire fusiform root, measuring up to 20 cm. in length and up to 2.5 cm. in thickness at the crown, or broken or cut into pieces; usually cut lengthwise into two or four sections; externally light yellowish, wrinkled longitudinally, somewhat annulate, root scars distinct and corky; fracture tough when damp, brittle when dry; internally, cortex whitish and characterized by numerous, reddish-brown oleoresin cells, cambium zone distinct and brownish; wood about the same thickness as the cortex, slightly radiate and light yellow. Odor aromatic; taste sweetish and pungent. The powdered drug, when examined under the microscope, shows numerous truncate or somewhat angular starch grains up to 0.03 mm. in diameter, reticulate tracheae up to 0.06 mm. in width and thin-walled, lignified fibers with simple pores. Parsley Root yields not more than 6 per cent, of ash." N.F. IV.

All parts of the plant contain a volatile oil, to which it owes its odor and mainly its taste, as well as its use in seasoning. This oil consists of a hydrocarbon, C₁₀H₁₆, probably pinene, and apiol. Braconnot (B. Chem. G., 1876, 1121) obtained from the herb a peculiar substance, resembling pectic acid in appearance, which he named apiin. This has been stated to be a glucoside but Joret and Homolle believe it is identical with pectin. It is soluble in hot water and on cooling forms a gelatinous mass. When purified it forms silky needles of the formula C₂₇H₃₂O₁₆. Apiol, or parsley camphor occurs as a white crystalline solid with a faint odor of parsley, insoluble in water but soluble in alcohol, ether and fixed oils. It is the di-methoxymethylene ether of allyl-tetraoxybenzene, C₁₂H₁₄O₄

Ciamician and Silber (Ph. Post, 1888, 391) have investigated apiol, and state that the pure substance occurs in white crystals having the composition C₁₂H₁₄O₄, melting at 30� C., and boiling at 294� C. Isapiol, apiolic acid, apiolaldehyde, and apion are decomposition products. They state that isapiol has physiological properties resembling those of pure apiol.

The term " apiol" or " liquid apiol" is often applied to the oleoresin (Oleoresina petroselini U.S. IX) also often known, as oil of parsley seed. The method of preparation of this was as follows:

" Parsley Fruit, in No. 60 powder, five hundred grammes; Ether, a sufficient quantity. Place the parsley fruit in a cylindrical glass percolator provided with a stop-cock and arranged with a cover and a receptacle suitable for volatile liquids. Pack the powder firmly and percolate slowly with ether, added in successive portions until the drug is exhausted. Recover the greater portion of the ether by distillation on a water bath, and, having transferred the residue to a dish, remove the remaining ether by spontaneous evaporation in a warm place, stirring frequently. Allow the Oleoresin to stand without agitation for four or five days, decant the clear liquid portion from any solid residue, and preserve it in well-stoppered bottles." U. S. IX.

Parsley root was used chiefly as a diuretic in dropsies and various inflammatory conditions of the urinary organs. Cow (A. E. P. P., 1912, Ixx, p. 393) has shown, however, that it has very feeble physiological action.

The oleoresin of parsley contains a number of bodies of considerable physiological power. The most important of these are crystalline apiol, white apiolin, and myristicin. According to the experiments of Lutz (Bull. Sci. Pharm., 1910, xyii, p. 1) the actions of these substances are similar in kind. They produce marked slowing of the pulse with fall of the blood pressure, tremors, and weakness of the extremities, followed by paralysis with epileptiform convulsions and gasping respirations. After death there was found marked congestion in the lungs and in the pelvic organs. Rimini and Dilitala (Archiv. di. Farmacologia e. Terap., 1908, xiv) have shown that apiol produces in the cat fatty degeneration of the liver of the same type as is caused by myristicin (see under Oleum Myristicae). They also noted that it had a direct weakening action on the voluntary muscles.

Apiol has been attributed with the possession of antiperiodic properties, but is chiefly employed in dysmenorrhea and other uterine disorders. There is, however, no satisfactory evidence that we know of, either experimental or clinical, that it possesses any real therapeutic value.

Glatard (Journ. de Med. et Chir. Prat., 1910, p. 674) report a case of apiol poisoning in a pregnant woman who took six grammes in a period of forty-eight hours. There was vertigo, nausea and vomiting, urticaria, liver swollen and painful, mild icterus, urine scanty and high colored, but free from albumen; pregnancy was not interrupted. Sardou (A. G. M., 1906) recommends apiolin as an antispasmodic in intestinal colic.