On Witches’-Broom of Pyrus japonica, 
BY 
A. W. BORTHWICK, D.Sc. 
With Plates IV. and V. 
The peculiar hypertrophy of branches known as “ witches’- 
broom” is not of uncommon occurrence on various members of 
the Rosaceze, although the deformation is by no means peculiar 
to this family, but is to be observed frequently on various 
other broad-leaved trees and on Conifere. As a general rule 
_the buds of the “ witches’-broom” unfold in spring in advance of 
the buds of the normal twigs, but, as Dr. W. G. Smith* points 
out, the “witches’-broom” of A/nus is exceptional—its buds 
opening after those of the normal twigs. 
The figures accompanying this note show a fine “ witches’- 
broom” on a bush of Pyrus japonica growing in the Royal 
Botanic Garden, Edinburgh. Plate I'V.,fig. 4, is from a photograph 
taken in October, 1902, and it shows the “broom” with the 
leaves still on it, while the rest of the bush is practically leafless. 
Plate IV., fig. a, is from a photograph taken a month later, and 
shows the “broom” as well as the bush in an almost leafless 
condition. Unfortunately, gales during the winter broke off the 
largest part of the “broom,” leaving only a small portion still 
attached, and this is shown in Plate V., fig. c, from a photograph 
taken in February, 1 
At the date of this photograph the plant had a very good 
covering of young green leaves and flowers, but the “broom” 
showed not only no signs of leaves, but no bud-activity whatever, 
*W. G. Smith, Untersuchungen d. Anat. u. Morph. der durch Exoasceen 
verursachten Deformationen. Inaug. Diss., Munich, 1894, p. 16. 
(Notes, R,.B.G, Edin., No. XVI, 1905. 
