upper surface. Moreover they appear white in colour, presumably due to the refractile nature
of the cavity, whereas the brittle hairs are glass-like and transparent. I suspect that the soft
hairs are simply composed of hollow dead cells with cellulose walls, whereas the brittle cells
are somehow impregnated with silica.
In the minor elms the soft curly hairs occur on the underside of the leaves as axillary tufts at the
junction of the main veins and the midrib and are up to 1.0mm long, and there are no brittle
spiny hairs on either surface. In V. procera the soft hairs tend to occur along the surface of the
veins as well as in axillary tufts, and are also scattered across the lower lamina. Brittle spiny
hairs also occur on the underside along the main veins, however, intermixed with soft hairs.
The ruby-tipped glandular hairs, are minute by comparison, hardly l/10th the size of the other
hairs. In young leaves of both the minor and procera elms they occur in thousands along all the
veins, including the ultimate venules. They are most readily seen by holding a leaf up to the sky
under a x20 lens and looking for the almost transparent final venules, against which they will be
illuminated by the light transmitted through the leaf. In both taxa they also occur along the main
veins on the upper surface of some of the leaves. The ruby glands also occur, though usually at
a much lower density, on the leaves of the various U. minor x glabra hybrid clones. What can
they be for? The lower leaf surfaces have numerous strange carrot shaped mites all over them,
of about the same size as the glands. Can they be some sort of defence against these? They seem
to burst rather readily and distribute their red contents as a splodge on the lamina surface.
As for the spiny hairs, why are they produced by the Atinian/English Elm? Columella tells us
that cattle prefer the taste of the leaves to those of other elms. Could they have evolved as
some sort of defence against browsing of the palatable mature leaves? Maybe they are not so
vicious or plentiful on the juvenile leaves that would develop after lopping.
16
Essex Field Club Newsletter No. 46, January 2005