Source, Etc

The witch hazel, Hamamelis virginiana, Linne (N.O. Hamamelideoe), is a common shrub in the United States and Canada. It attains a height of about 3 metres and resembles the common hazel both in its leaves and its fruit, which is edible. The bark should be collected in the spring.

Description

Witch-hazel bark occurs in thin channelled pieces of a characteristic, pale reddish pink colour, occasionally as much as 15 or 20 cm. long and 2.5 cm. wide, but usually much smaller. They are sometimes covered with an ash-grey smooth cork which in older pieces becomes darker in colour, fissured, and scaly. Frequently the cork has been removed and the cortex forms the outer layer, which is then pale reddish brown in colour and nearly smooth, exhibiting under the lens slight transverse striations.

The inner surface is pale reddish pink in colour and finely striated longitudinally; small portions of white wood, which is seen in transverse section to be dense and traversed by numerous thin medullary rays, are frequently found adhering to it.

The outer portion of the bark (cork and cortex) breaks with a short fracture, but the inner portion (bast) is coarsely fibrous and disposed to separate into laminae, due to its containing numerous tangentially elongated groups of bast fibres. The smoothed transverse section exhibits under the lens a dark narrow cortex and a pale tangential line (sclerenchy-matous cells) separating this from the bast. In many of the pieces the cork and much of the cortex have been removed, and the ring of scleren-chymatous cells may then form the outer layer.

The bark has no odour, and an astringent, slightly bitter taste. The student should observe

(a) The reddish pink colour,

(b) The pale grey but not glossy cork,

(c) The line of sclerenchymatous cells between the cortex and bast; and should compare this bark with

(i) Oak bark, which has a glossy, silvery cork and usually a brownish colour,

(ii) Willow bark, which has a dull greenish brown cork, is usually longitudinally striated on the outer surface, and does not exhibit a line of sclerenchymatous cells.

Constituents

The bark contains about 6 per cent, of tannin, part of which, hamamelitannin, is said to be crystalline and part amorphous; gallic acid is also present (Gruttner, 1898).

Uses

It is astringent and haemostatic, and is useful in haemorrhages from the nose, lungs, rectum, or uterus.

Fig. 130.   Witch hazel bark, showing scaly cork. Natural size.

Fig. 130. - Witch-hazel bark, showing scaly cork. Natural size.