_Elm Bark_; F. _Ecorce d’Orme_; G. _Ulmenrinde_, _Rüsterrinde_.
=Botanical Origin=—_Ulmus campestris_ Smith, the Common Elm, a stately
tree, widely diffused over Central, Southern and Eastern Europe,
southward to Northern Africa and Asia Minor, and eastward as far
as Amurland, Northern China, and Japan. It is probably not truly
indigenous to Great Britain; but the Wych Elm, _U. montana_ With., is
certainly wild in the northern and western counties;[2063] the latter
is, according to Schübeler, the only species indigenous to Norway.
History—The classical writers, and especially Dioscorides, were
familiar with the astringent properties of the bark of πτελέα, by
which name _Ulmus campestris_ is understood. Imaginary virtues are
ascribed by Pliny to the bark and leaves of _Ulmus_. Elm bark is
frequently prescribed in the English Leech-books of the 11th century,
at which period a great many plants of Southern Europe had already been
introduced into Britain.[2064] Its use is also noticed in Turner’s
_Herbal_ (1568) and in Parkinson’s _Theater of Plants_ (1640), the
author of the latter remarking that “all the parts of the Elme are of
much use in Physicke.”
In the Scandinavian antiquity the fibrous bark of _Ulmus montana_ used
to be made up into ropes.[2065]
=Description=—Elm bark for use in medicine should be removed from
the tree in early spring, deprived of its rough corky outer coat,
and then dried. Thus prepared, it is found in the shops in the form
of broad flattish pieces, of a rusty yellowish colour, and striated
surface especially on the inner side. It is tough and fibrous, nearly
inodorous, and has a woody, slightly astringent taste.
=Microscopic Structure=—The liber, which is the only officinal part,
consists of thick-walled, tangentially-extended parenchyme, in which
there are some large cells filled with mucilage, while the rest contain
a red-brown colouring matter. The mucilage forms a stratified deposit
within the cell. Large bast-bundles, arranged in irregular rows,
alternate with the parenchyme, and are intersected by narrow, reddish,
medullary rays consisting of 2 or 3 rows of cells. The bast-bundles
contain numerous long tubes about 30 mkm. thick, with narrow cavities;
and besides these, somewhat larger tubes with porous transverse
walls (cribriform vessels). Each cubic cell of the neighbouring
bast-parenchyme encloses a large crystal, seldom well defined, of
oxalate of calcium.
[2063] On the word _elm_, Dr. Prior remarks that it is nearly
identical in all the Germanic and Scandinavian dialects, yet does
not find its root in any of them, but is an adaptation of the Latin
_Ulmus_.—_Popular Names of British Plants_, ed. 2. 1870. 71.
[2064] _Leechdoms, Wortcunning and Starcraft of Early England_, edited
by Rev. O. Cockayne, ii. (1865) pp. 53. 67. 79. 99. 127 and p. xii.—In
the Anglo-Saxon recipes, both _Elm_ and _Wych Elm_ are named in the
Welsh “_Meddygon Myddfai_” (see Appendix). Elmwydd or Ilwyf and “Ulmus
romanus,” Ilwyf Rhufain, are met with.
[2065] Schübeler, _Pflanzenwelt Norwegens_, 1873-75, p. 216.
=Chemistry=—The chief soluble constituent of elm hark is mucilage with
a small proportion of tannic acid, the latter, according to Johanson
(1875), probably agreeing with that of oak bark and bark of willows.
The concentrated infusion of elm bark yields a brown precipitate with
perchloride of iron; the dilute assumes a green coloration with that
test. Starch is wanting, or only occurs in the middle cortical layer,
which is usually rejected.
Elms in summer-time frequently exude a gum which, by contact with the
air, is converted into a brown insoluble mass, called _Ulmin_. This
name has been extended to various decomposition-products of organic
bodies, the nature and affinities of which are but little known.[2066]
=Uses=—Elm bark is prescribed in decoction as a weak mucilaginous
astringent, but is almost obsolete.