PLANTS APPARENTLY INCAPABLE OF HYBRIDIZATION. 
157 
strongest bud that is breaking, near the top, 
and rub all the others off, that the whole 
strength may go the elongation of that branch, 
till it has reached where it may branch. But 
there are some climbers that are most effective 
when allowed to grow wild ; that is to say, - 
when they have covered the space wanted to 
be embellished, and the top allowed to get wild 
and bushy. Care must be taken in this case to 
fasten all the upper parts of the branches very 
strongly, because the head is of great weight, 
and would draw the nails, unless there are 
plenty of them, and they have good hold. 
The common or scented clematis is of this 
description ; the honeysuckle is especially so. 
The passion-flower is always more elegant 
when thus left at liberty ; but they must be 
annually trimmed, moderately, indeed we may 
say pretty close, because they are sure to 
grow wild enough. The best effect is pro- 
duced by dividing the wall into panels, or 
equal widths ; for each and the various sub- 
jects may be trained to fill their allotted width 
at bottom, after which all the growth would 
be upwards. A wall filled with different climb- 
ing plants has the prettiest effect ; but if the 
plants are allowed to run up without filling 
the bottom at starting, there will be no getting 
them right afterwards, without actually cutting 
them down again; and whether it be a common 
fruit-tree, or any other plant trained, nothing 
looks worse than to see the walls bare at the 
bottom. Of course, there are hundreds of 
different climbing plants, but the principles are 
the same, and the management should be simi- 
lar. Another mode very successfully adopted 
on the fronts of houses is to train things natu- 
rally of a dwarf habit to finish to the top of 
the lower windows and door, and to train others 
with single stems up to that height, and then let 
them fill the upper part of the front ; by this 
means the two portions foi*m a very different 
feature, but highly interesting and effective. 
The Wistaria sinensis is well adapted for the 
upper part, for a" single stem of that plant 
could be grown thirty or forty feet high, if 
necessary, and all the beauty of the plant be 
commenced at any height. Perhaps there is 
nothing more neglected, in a general way, than 
climbing plants ; and this fact induces us to 
select that subject for the present paper. 
OBSERVATIONS ON PLANTS WHICH AP- 
PEAR INCAPABLE OP HYBRIDIZATION. 
BY M. LOISELEUR DESEONGCHAMPS. 
( Translated from the Ghent A nnales.) 
About four years ago, having occasion to 
speak of Mr. Lecoq's work on hybridation, I 
expressed some doubt as to the possibility of 
practising this process equally on all kinds of 
plants ; at the same time I was not unaware 
of the great advantages that may be obtained 
by hybridation. I had frequently recommended 
one of my friends, residing in Provence 
(France), and in whose garden Datura, ar- 
borea had been frequently crossed, to try to 
obtain a hybrid from the magnificent flowers 
of that plant, and the violet flowers of U. 
fastuosa. Latterly I endeavoured to av.iil 
myself of the genialness of the climate in 
which he resided in trying to cross several 
species of Amaryllis and Passiflora, in order 
to obtain new varieties. But however ready 
to admit the power of this process to modify 
species, I am still of opinion that it has its 
limits, and that there are genera which, from 
the nature and conformation of their flowers, 
will not admit of its successful application by 
any mode of procedure whatever. However, 
a great many horticulturists are so persuaded 
of the possibility of hybridizing in all cases, 
as to believe that the slightest variety they 
meet with is the result of this practice of 
crossing, though it has not really any influ- 
ence in their production. But to return to 
the difficulty, or rather the impossibility, of 
crossing certain plants. 
After having carefully studied the develop- 
ment of the flowers of wheat, in trying to 
ascertain what could be the causes which had 
produced so great a number of varieties of 
that genus, and if the application of the pol- 
len to the stigmas of the different species 
might not produce modifications of form and 
new varieties, I was led by experience and 
observation to ascertain that the fecundation 
of the female organs of these plants took 
place secretly — that is to say, the pistils were 
impregnated with the pollen of the anthers 
before the calices were yet open. From this 
circumstance it has appeared to me that hy- 
bridation in such kinds of wheat is impossible, 
either artificially or naturally, and conse- 
quently, that the numerous varieties which 
exist in this genus have all been produced 
by unknown causes, but which are something 
different from what is called hybridation. But 
wheat is not the only plant which seems to be 
incapable of hybridation. Thirty years ago, 
and at a time when artificial crossing was 
much less in vogue than it is at the present 
day, I was induced to try to obtain some new 
varieties in the poppy (Papaver), by crossing 
the species of Tournefort, the flowers of which 
have remained to the present of so bright red 
a colour, with the poppy of our gardens, which 
on the contrary has produced a great many 
varieties of colour ; but I could not succeed 
at all, for I found, in submitting Tournefort's 
poppy to the process of impregnation, that 
before the calyx of the two sepals which en- 
velope the petals and the organs of generation 
