Meddelanden af Societatis pro Fauna et Flora Fennica - Helda

7. XI. 1903. E. Reuter, Hexenbesen und Eriophyiden. 35
lung der genannten Zweigdeformationen von deren erstem Be-
ginn ab verfolgte. Ich erlaube mir ihre Darstellung hier z. T.
wörtlich anzufiihren :
»The
formation of the Witch-knots begins
with a diseased growth of the mite-infested bud, \vhich is
distinguishable by its svvelled, irregiilar, loosely-opened appear-
ance, from the smooth and pointed shape of the buds in heahhy
condition; and presently . . . the
attacked shoot is thickly covered
by the buds, which in healthy growth would have been distri-
buted at distances of some inches along it. As time goes on,
repeated forkings of the twigs from these unhealthy and infested
buds, and from successive growths of the same kind, give rise
to the knotted and confused masses known as Witches' Brooms.
Sometimes these make htlle progress, and the knot merely
resembles a rough mass Hke an old Book's nest thrown down
and hanging loosely from the Birch bough; sometimes the twigs
regain healthy gro\vth, and pushing on for as much as a yard
in length form a pendant mass of some beauty, from the deli-
cacy and gracefulness of the sprays.
The infested buds . . . may be distinguished by their sphe-
roidal shape, greater size, and loosely imbricated irregular scales,
from the natural growths, which are smooth and lanceolate in
general outline. A few months later (about the beginning of
February), a touch to one of these distorted buds will often
throw off ali the diseased scales, and at their bases the coming
growlh will be found in the numerous minute round buds set
close together on the common thickened centre . . . The
growth
of the knot from these embryo buds is the work of years; but
whilst the tree is still bare of leaves it may be found in every
stage of progress: the shortened shoot beset with swollen
buds...; the compound form, \vhere many buds have grown
close together so as to present a hard cluster, with a few shoots
starting from it . . . and so on\vards, tili the Witch-knot is fully
formed, a mass sometimes more than a yard in diameter>.^ —
Diese Bemerkungen werden von instruktiven Fig-uren erläutert.
' Ormerod, Manual etc, Sec. Ed., S. 21.3—214.