132 THE ORCHID REVIEW. [May, 1908 
which trickles down the bark from the smaller branches above, such 
moisture containing the necessary chemical matters in a state of solution. 
Among epiphytes, too, we find various modifications of the stem into 
pseudobulbs, which are storehouses of water and nutrient matter, to tide the 
plants over a dry period. Sometimes the leaves themselves become fleshy, 
thus forming such storehouses. The infloresence and flowers have also 
become specialised in various ways with which we are more or less familiar. 
The essential feature of the group as regards fertilisation is that when an 
insect visits the flower, it touches the rostellum, which immediately liberates 
a quantity of viscous matter on the head or shoulders of the insect, and this 
serves to attach the pollinia to the insect, and when it flies away the pollinia 
are withdrawn, and on visiting another flower they come in contact with the 
viscid stigma, and are left behind, fertilization following naturally. 
We will now pass along to the Vandez, another very large tribe, widely 
‘diffused through tropical and subtropical regions, in which the culminating 
point of development in this particular branch is reached. The essential dif- 
ference between the Vandez and the Epidendree is that in the latter a portion: 
of the rostellum, in addition to the viscus or gland, becomes attached to the 
pollinia, and are removed with it by the fertilising insect. This character 
is well seen in Odontoglossum. Ifa pencil is inserted so as to touch the 
point just above the stigma, and then withdrawn, the pollinia will come 
away, and if examined it will be seen that they are attached toa slender 
white stalk, at the base of which the gland is situated. This stalk is called 
the stipes, and is a part of the rostellum which becomes separated through 
the production of a layer of special tissue, analagous with the layer of cells 
which cause the fall of an ordinary leaf in autumn. Thus the portion 
removed by the insect in the Vandee consists of the pollen masses, the 
stipes, which connects them to the viscid disc or gland, and the gland itself, 
and these collectively are called the pollinarium. It is a compound orga”, 
functionally male, but partly derived from the rostellum, which belongs to 
the female whorl. It is a good example of the high degree of specialisation 
to which the Orchid flower has attained. 
The Vandez is a very large group, containing many of our popular 
cultivated Orchids, as Odontoglossum, Oncidium, Angraecum, Phalenopsis, 
Vanda, Stanhopea, &c. It is divided into several subtribes, as Cymbidiee, 
Stanhopiee, Oncidiee, Sarcanthee, and others. We may now notice 
some of the species individually. 
Rodriguezia fragrans (now thrown on the screen) is a plant which grows 
in tufts on the branches of trees, and throws out numerous white roots 
around and beneath the plant, showing that it derives some of its food 
direct from the gases and moisture in the atmosphere, and possibly that 
it grows on small twiggy branches, which form a kind of collecting ground 
‘a 
4 
a 
