154 
THE PRINCIPLES OF BOTANY. 
have separate flowers on the same tree, the difficulty of con¬ 
tact will be somewhat increased, and hence these will be found 
to secrete a thousandfold more pollen than in the first case, 
so much so, indeed, that such large quantities are sometimes 
blown to great distances, and have been mistaken for showers 
of sulphur on being deposited. 
In the last case of separate trees for the distinction of 
flowers, as the difficulty of contact will be still greater, so we 
have still more pollen produced, so that in early spring it was 
amusing to illustrate this matter to our class by completely 
smothering them in pollen when we could get them under a 
male yew tree. 
These facts are of importance in horticultural observations, 
as in practice we can artificially fertilise plants, and thus 
produce new varieties, or we can bring together distant 
sexes, and so ensure fruiting. Some of these facts were well 
known to the ancients; and such knowledge was turned to 
practical account, as will be seen from the following, by Sir 
J. E. Smith:— 
The stamens and pistils of flowers have, from the 
most remote antiquity, been considered as of great import¬ 
ance in perfecting the fruit. The date-palm, from time 
immemorial a primary object of cultivation in the more tem¬ 
perate climates of the globe, bears barren and fertile flowers 
on separate trees. The ancient Greeks soon discovered that, in 
order to have abundant and well-flavoured fruit, it was expe¬ 
dient to plant both trees near together, or to bring the barren 
blossoms to those which were to bear fruit; and in this 
chiefly consisted the culture of this valuable plant. Tourne- 
fort tells us that without sueh assistance dates have no 
kernel, and are not good food. The same has long been 
practised, and is continued to this very day in the Levant, 
upon the pistacia and the fig/^ 
We have somewhere read that in the East an annual pro¬ 
cession was wont to be made to the date-palm groves, when 
the priests, armed with bunehes of male flowers (commonly 
called palms), waved them with prayer and much ceremonial 
among the fruiting examples, the omission of which, we can 
well understand, would not eventuate in a blessing. It may 
be a curious subject for inquiry whether the strewing of palm 
by way of rejoicing did not originate from this custom. The 
nearest imitation of palm we have in this country, namely, 
the male catkins of the willow, is employed in our houses and 
churches on Palm Sunday in commemoration of these ancient 
rejoicings. 
