518 THE DICTIONARY 
be : 
OF GARDENING, 
Orchid Fertilisation—continued. 
labellum have reversed the positions they occupy in the 
other forms. In the large group of Epidendree, of which 
so many are cultivated in hot-houses, the adaptations for 
cross-fertilisation, though less complex than in Catasetum, 
well deserve a short notice. Cattleya is selected as an 
easily-obtained type; but Lelia, Chysis, and other genera, 
only differ from Cattleya in minor details. The positions 
of the labellum and of the column will be readily made 
Fic. 766. CATTLEYA TRIANA. 
out (see Figs. 762, 765, and 766). The column is promi- 
nent, and arches forward, having the stigmas on the front 
or lower surface, near the tip. Just beyond them is the 
rostellum, the lower surface of which is thickly covered 
with sticky liquid. Beyond this, again, on the tip, is 
the anther. The pollen grains are joined to form four 
chief masses, which end in caudicles, to which many 
separate small groups, each of four grains, are stuck. 
The caudicles have no disks; they lie so that their 
tips are on the dry, membranous, upper surface of the 
rostellum. The labellum usually has the sides folded up 
so as to nearly surround the column. The nectary is a 
narrow tube between the labellum and the base of the 
column in front. When an insect of suitable size comes 
to suck the nectar, it must push its way between the 
labellum and the front, or lower, surface of the column; 
Orchid Fertilisation—continued. 
and must get well in below the latter before reaching 
the nectar. In doing this, its back presses against the 
stigmas, and leaves on them pollen from any previously 
visited flower. In retreating, the insect presses its back 
against the lower surface of the rostellum, and becomes 
smeared with the fluid, some of which is also forced on 
to the caudicles, and causes them to stick to the insect; 
and the pollinia are thus drawn out and fixed to it, to 
be transferred to the next flower visited. It will be 
observed that the method of affixing the pollinia in these 
plants reminds us a little of that previously described as 
occurring in Listera ovata; but the larger size renders it 
more easy to study the process in Cattleya and its allies, 
and the differences in details are sufficiently obvious. 
Some Orchids are now so specialised to adapt them- 
selves for cross-fertilisation alone, that the stigma dies 
(as if poisoned) when pollen from the same 
flower is placed on it; e.g., species of Bur- 
lingtonia and of Oncidium. Between this 
extreme and habitual self-fertilisation in 
cleistogamic flowers, every stage is to be 
encountered. In many cases, where me- 
chanical obstacles prevent the pollen of a 
flower being transferred to its stigma, the 
ovules are well fertilised (e.g., in Orchis 
maculata) if pollen is placed on the stigma 
of the same flower. 
An interesting example of the way in which 
an Orchid, possessed of structures intelli- 
gible in their origin only as suited to cross- 
fertilisation, is converted by a slight altera- 
tion, so as to enable its ovules to be fer- 
tilised by pollen of the same flower, is well 
seen in the Bee Orchis (Ophrys apifera). 
In this plant, the parts are, in many respects, similar 
to those of Orchis maculata; but the pollinia have long, 
slender, flexible stalks, and the mass of grains in each 
slips out of the pouch of membrane, and in front 
of the stigma, retained by the disk, and the slightest 
swaying movement causes it to strike against the stigma, 
and to leave pollen on it. The flower is not much, if 
at all, visited by insects, and it possesses no attractions 
for them. 
A striking anomaly is that observed by Dr. F. Müller, 
in South Brazil, in which an Epidendrum possessed two 
lateral stamens that secured self-fertilisation, and a 
median one, from which the pollen could be removed 
only by insect or other extraneous aid. The rarity with 
which this is effected, is indicated by the absence of 
attractions for insects in the flower. A considerable 
number of self-fertilised Orchids have been put on 
record. One of the latest papers on this subject is 
entitled, On the Contrivances for Insuring Self-Fertili- 
sation in some Tropical Orchids,” by Henry O. Forbes, 
in the “Journal of the Linnean Society,’ vol. xxi., 
pp. 538-49, tt. 16 & 17. 
ORCHID HOUSE. This term is applied to any 
garden structure in which Orchids are cultivated, to the 
exclusion of all, or nearly all, plants of another descrip- 
tion. It is not necessary, nor, indeed, always thought 
advisable, to relegate these plants to certain houses by 
themselves; but in nurseries, where space for thousands 
of living imported specimens have frequently to be 
found, and a large collection of established plants is 
also grown, not only are special Orchid Houses found 
necessary, but large structures are frequently devoted 
wholly to the accommodation of such genera as Cattleya 
or Odontoglossum alone. Nor is this system entirely 
limited to nurseries; many private collections have now 
become so extensive, in consequence of the frequent 
additions made, that similar arrangements are being 
adopted. Where large and varied collections of Orchids 
are grown, they are usually arranged, according to the 
