Hydrangea. Seven Barks, Common Hydrangea. Hydrangea arborescens.
Hydrangea, N. F. IV. Seven Barks. Common Hydrangea. (Fam. Saxifragaceae.)—It is described by the N. F. as "the dried rhizome and roots of Hydrangea arborescens Linne. (Fam. Saxifragaceae.) Rhizome cylindrical, usually cut into pieces from 3 to 10 cm. in length and from 3 to 20 mm. in diameter; externally light brown to yellowish-brown with a pinkish tinge, longitudinally wrinkled, marked by few elliptical lenticels and occasional prominent buds, short branches or stem scars; from the lower surface arise a few coarse fibrous roots; fracture tough, splintery; internally yellowish-white or light brown, bark thin, easily separable from the distinctly radiate wood which surrounds a prominent whitish pith. Roots attaining a length of 25 cm. and a thickness of 2 mm., irregularly bent and branching, otherwise resembling the rhizome with the exception of the pith being absent. Inodorous; taste sweetish, becoming slightly acrid. Under the microscope, sections of the rhizome of Hydrangea show a gray cork of a few rows of tabular cells, a cortex made up chiefly of parenchyma containing starch, large cells containing raphides and small isolated groups of stone cells or sclerenchymatous fibers; a woody cylinder composed of slender wedges made up of prominent tracheae with reticulate thickenings and tracheids separated by medullary rays one to three cells wide, the cells of which are filled with small starch grains; pith of large polygonal cells with prominent simple pores. The powder is light yellowish-brown, containing irregular fragments consisting of strongly lignified tracheae, tracheids and medullary ray cells; stone cells and sclerenchymatous fibers from 0.05 to 0.2 mm. in length, strongly lignified, the walls marked by simple and branching pores; raphides numerous, from 0.07 to 0.13 mm. in length; starch grains mostly single, more or less ellipsoidal, occasionally with a prominent central cleft and varying from 0.002 to 0.01 mm. in diameter. Hydrangea yields not more than 3 per cent. of ash." N. F.
Bondurant (A. J. P., 1887, 122) isolated a characteristic glucoside, hydrangin, crystallizing in stellate clusters, melting at 235° C. (455° F.), and subliming without decomposition. It is decomposed by dilute acids into a resin-like body and glucose. Its aqueous solution fluoresces strongly on addition of an alkali, resembling aesculin, but distinctly different in several particulars. Bondurant also obtained a fixed oil and a volatile oil, the latter containing sulphur. Two resins seemed also to be present, together with saponin and sugar. He found no tannin, however. Y. Asahina has isolated two crystalline substances from the alcoholic extract of the flowers of H. Hortensia; hydragenol and hydrangeaic acid. The first occurs in white, odorless and tasteless crystals which are soluble in alkalies and dissolve in sulphuric acid without color; hydrangeaic acid forms yellowish, shining crystals, and its alcoholic solution when treated with ferric chloride yields a violet color. Its decoction is said to have been used with great advantage among the Cherokee Indians, and subsequently by settlers, in calculous diseases. (See N. J. Med. Rep., 1850, 1854, and 1885.) In overdoses it occasions vertigo, oppression of the chest. etc. Dose, thirty grains (1.9 Gm.).