292 THE FLORAL WORLD AND GARDEN GUIDE. 
plants are not of much account for decorative purposes in Europe, 
they attain to great beauty in tropical countries, whence numerous 
importations have lately been received in our hothouses. 
For a dozen years past, aroids, in the shape of Alocasias, Colocasias, 
Caladiums, Anthuriums, and Philodendrons, have been in high 
esteem amongst admirers of hothouse plants. Naturally, the 
possibility of improving them soon suggested itself to those who 
knew the secret of their culture, and knew, too, the profit to be 
made by introducing new varieties. A Frenchman, M. Bleu, was 
the first who discovered a means of surpassing nature by modifying 
the type and colours of the variety of Oaladium known as E’ Ama- 
zone, which was sent out by M. Chantin in 1858. 
When first they appeared, these varieties created a great sensation 
amongst connoisseurs. Now perfection has been very nearly 
attained, and to modify the varieties already in existence, it would 
probably be necessary for M. Bleu to originate a new strain with 
his Hybrid Caladium with pure, transparent, white, parchment-like 
leaves. Abroad, it has been at Vienna more particularly that aroids 
have been made the subject of scientific study. An article con- 
tributed to the Gardener's Chronicle by M. Karl Koch, contains 
some useful information in point, which it may be well to analyse. 
It was at Erfurt, abont fifteen years ago, that M. Kellermann 
exhibited the first aroids in bloom. The exhibition was of great 
interest both to botanists and florists. _M. Kellermann had worked 
from 1850 to 1860 under Schott, who was at that time director- 
general of the Imperial Gardens at Schonbrunn. He it was that 
formed the famous collection of more than four hundred aroids, 
which became the basis of his subsequent labours. The study of 
these numerous varieties suggested to M. Kellermann the idea of 
devoting them to experiments in cross-fertilization. I have already 
mentioned a singular fact relative to the fertilization of Arum 
muscivorum. It should be observed that Caladium odorwm is also ferti- 
lized in the ordinary way. Every year I get a crop of fertile seeds 
from it, which ripen perfectly in the temperate-house. 
Now, regarding M. Koch’s theory of the matter. Aroids, let it 
be observed, as a rule are not self-fertilized. The flowers on the 
spadix require impregnation with the pollen of another plant of the 
same species or variety. When the stigma is ready for impregna- 
tion, the pollen is still enclosed in the anthers, which explains the 
need of two distinct plants of the same kind for the consummation 
of the act of fertilization. The sensibility of the stigma is of very 
short duration. It varies according to the season; but as a ‘rule 
does not continue longer than four or five hours at the outside. 
Generally it manifests itself in the night, when the spathe first 
opens, and most often when the heat of the spadix is appreciable. 
This sensibility is rarely of longer duration—as in the Caladiums, 
for instance. The pollen, too, quickly loses its power of impregna- 
tion, and will not keep good for more than two or three days. 
To sum up. Hot-house aroids are rarely self-fertilized, so that 
to get good seed it is absolutely necessary to resort to artiticial 
fertilization. 
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