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n6 The Trees of Great Britain and Ireland
Gilbert White thought that male trees are more robust in growth than female
trees ; but we are unaware of any accurate observations on this subject. Kirchner, 1
however, states that there is a slight distinction in the habit of the two sexes, male
trees being taller with longer internodes and shorter leaves.
In early spring drops of mucilage may be observed glistening on the ovules of
female trees in flower. The mucilage is secreted by the micropyle, and seems to
entangle the grains of pollen which have been wafted on the ovules by the wind.
The clouds of pollen which fly forth from the male flowers are well known. The
pollen is liberated from the stamens by a very elaborate mechanism, which serves to
protect the pollen grains in rainy weather. A good account of this is given by
Kerner.2
A large quantity of fruit of the yew falls to the ground in autumn ; but the seeds
in this case do not as a rule germinate. Natural reproduction seems to be effected
by birds like the thrush and blackbird, which, attracted by the fleshy aril, devour the
whole fruit. The seeds, protected by their hard testa, escape digestion and are
voided at a distance. They rarely germinate in the first year after ripening;
seedlings come up as a rule in the year following, a few even appearing in the
third year.
The buds of the different geographical forms appear to differ more than the
leaves themselves. The terminal bud is invested closely by the uppermost and
youngest leaves and continues the growth of the shoot. The bud scales on unfold
ing remain at the base of the growing shoot, and on older branchlets persist as dry
brownish scales, forming an involucre at the bases of the branchlets. Lateral buds
are developed on the twigs at irregular intervals. Many of these remain dormant,
retaining the power to take on growth at any moment. This explains the readiness
with which the yew submits to pruning, and the facility with which it produces
coppice shoots when the stem is cut. Spray or epicormic branches are frequently
produced on the upper side of the branches or on the stem; and these also originate
in dormant buds.
True root-suckers are never formed; but layering occurs, though very rarely,
in branches which have come in contact with the ground. (A. H.)
AGE, HARDINESS
With regard to the supposed great age of yew trees, which has been much
exaggerated by authors especially by the great Swiss botanist, De Candolle we
must refer our readers to Lowe, who has discussed the subject very thoroughly
in chapter iii. of his work. He proves that the average rate of growth is about
i foot of diameter in 60-70 years in both young and old trees. There is, however,
abundant evidence to show that though old trees grow at intervals much more
rapidly than young ones, they do not grow uniformly, but have periods of com
parative rest, and that the increase of girth is fastest when old trees have lost their
heads and the stem is covered with young shoots.
1 Kirchner, loc. cit. 74. « Nat. Hist. Plants, Eng. translation, ii. 145, 146 (1898).
Taxus 117
No tree has such a remarkable faculty of covering up wounds or injuries by the
growth of fresh wood from the outside ; and even after the main stem is completely
dead, fresh and entirely new stems may grow up around it and form a new tree
around the dead one. For this reason most of the yews of very large size are
mere shells, and even when no hollow can be seen from the outside, decay which
is often indicated by moisture running from holes in the trunk has set in.
Three very curious sections showing the way in which these trunks grow are
given by Lowe, pp. 78 and 79.
The yew, though occurring wild far north, as in Norway, is not perfectly hardy,
and many instances are on record in which it has been injured or killed during severe
winters. It was affected in Cambridgeshire 1 and severely injured at Glasgow by the
severe frost of 1837-1838. In the winter of 1859-1860 the young shoots of many
trees were killed at Burton-on-Trent. 2
Many cultivated yews 3 were killed by the frost of 1879-1880 in Switzerland,
Rhineland, Hessia, Thuringia, etc. though in the same localities other native conifers
were not injured by the severe cold. Duhamel 4 states that in France the yew
suffered much damage from the great frosts of 1709 ; and Malesherbes found several
killed by the frost of 1789.
POISONOUS PROPERTIES OF THE YEW
The poisonous properties of the yew have been well known from the earliest
times, and the subject has been so carefully investigated in the Journal of the
Royal Agricultztral Society of England, 1 892, p. 698, by Messrs. E. P. Squarey,
Charles Whitehead, W. Carruthers, F.R.S., and Dr. Munro, and summarised by
Low in chapter x. of his work, that we need not do more than give a brief
rdsumd of the present state of our knowledge. Through the kindness of Sir
W. Thiselton Dyer, we have been able to peruse a file of the Board of
Agriculture entitled "Yew Poisoning," in which the subject has been further
discussed by that gentleman with whose opinions we are in complete accordance.
The conclusions drawn by Dr. Munro, after careful study from a medical
point of view, are as follows :
" Both male and female yew leaves contain an alkaloid.
" This alkaloid in both cases appears to agree with the taxine of Hilger
and Brande. Taxine is probably the poison of the yew, but it is doubtful
whether it has ever been obtained in a pure state, and its physiological effects
have not been sufficiently studied. Other alkaloids are probably present in yew.
" Taxine is present in fresh yew leaves as well as in those withered or
air-dried. It is also present in the seeds, but not in the fleshy part of the fruit.
" The yew poison may be one of moderate virulence only, and may occur
in greater percentage in male than in female trees, or the percentage may vary
from tree to tree without distinction of sex, and this may explain the capricious
1 Lindley, Trans. Hort. Soc. 1 842, ii. 225.
3 Kirchner, loc. cit. 62.
2 Card. Chron. 1 860, p. 578.
4 Traitfde Arbres, i . 302 (1755)-