le flowers. It is not safe to depend upon pulling
off the male flowers of an isolated tree and leaving the female flowers
without bags to protect them from pollen of the same species or of
allied species, for the reason that wind may carry pollen to a great
distance. One of Mr. Burbank's critics--I am sorry he has so many, for
they are not all honest or serious--one of his critics, in relation to
the crossing of walnuts, said that it was due to no particular skill on
the part of Mr. Burbank, for, whenever the wind blew from the east, he
regretted to say that his entire orchard of Persian walnuts became
pollinized from the California black walnuts nearly half a mile away.
This is an exaggeration, because the chances are that most of the
Persian walnuts were pollenized from their own pollen, but in the case
of some Persian walnuts blossoming early, and developing female flowers
in advance of male flowers, pollen might be carried to them from half a
mile away in a high wind from California black walnut trees. Black
walnut pollen would then fertilize pistillate flowers of the Persian
walnut. I have found this a real danger, this danger of wind-pollination
at a distance, much to my surprise. Last year I pollinized one or two
lower branches of female flowers of a butternut tree which had no other
butternut tree within a distance of a good many rods, so far away that I
had no idea that the pollen would be carried from the tree with male
flowers to the one which happened to have female flowers only that year;
consequently I placed pecan pollen on the female flowers of the lower
branches of this butternut tree without protecting them with bags, and
left the rest of the tree unguarded. There were no male flowers on that
butternut tree that year. Much to my surprise, not only my pollinized
flowers but the whole tree bore a good crop of butternuts. This year, on
account of the drought, many of the hickory trees bore female flowers
only. I do not know that it was on account of the drought, but I have
noted that after seasons of drought, trees are apt to bear flowers of
one sex or the other, trees which normally bear flowers of both sexes.
This year a number of hickory trees bore flowers of one sex only, and I
noted that some shagbark trees which had no male flowers had fairly good
crops of nuts from pollen blown from a distance from other trees. I had
one pignut tree (H. Glabra) full of female flowers which contained only
one male flo