yo THE ORCHID REVIEW. { Marcu, 1908. 
ORCHIDS: THEIR STRUCTURE, DEVELOPMENT, AND 
FERTILISATION. 
Notes of a lecture given at a meeting of the Kéw Gardeners’ Mutual Improvement 
Society, held on February 17th, 1908, by Mr. R. A. Rolfe, A.L.S., and illustrated with | 
lantern slides. 
Tuer’ Natural Order Orchidacee is a very large and highly specialised 
family, the largest among Monocotyledons, comprising over 5,000 Species. — 
It is very widely distributed, the species being abundant in most of the 
warm and temperate parts of the globe, but avoiding cold and very dry 
climates, a few, however, extending to within the Arctic Circle. They are 
also rare in the remote oceanic islands. They particularly affect warm and 
moist situations within the tropics, especially on the mountains, and are 
very abundant on the Andes and the mountains of India and the Malayan 
Archipelago, but much rarer in Tropical Africa. Many of the species are 
epiphytic, and these are mostly confined to the tropics, where they have 
been literally driven up into the trees in the great forest. regions; 
because of the dark and uncongenial conditions of the forest floor. Here 
they have developed a number of curious adaptations which fit them for the 
new conditions of existence. Terrestial species are found over the whole 
area occupied by the Order, and are abundant in Australia and South 
Africa, and well represented in Europe, and temperate North and South 
America. | 
The family owes its peculiarity largely to the irregular development of 
the flower, which takes the form of suppression of some of the parts and the 
union of the remainder into two compound organs, known as the column and 
the lip, giving the flower a high degree of complexity. 
So great is this complexity in some. cases that it becomes very difficult 
to say what some of the parts really are. Take the case of Coryanthes 
‘macrantha (a photograph now being thrown upon the screen). Here is 4 
monocotyledonous flower, but could any except the initiated trace what Is 
termed the homology of the different parts? The large membranous 
bodies on one side of the flower consist of the sepals and petals, the lateral 
sepals being very iarge and curiously rolled back and twisted at the apex; 
with the much shorter dorsal sepal between them, and near by the narrow 
much curled petals. On the other side is a curious bucket-like arrange- 
ment, something like a milking pail, suspended on a nearly horizontal arm, 
at the angle of which is a helmet-shaped body, from which the genus takes 
its name, literally, ‘‘ helmet-flower.”” These parts collectively form the lip. 
What may be termed the handle of the pail, underneath the helmet, bears 
a number of deep transverse ridges. Continuous with the pedicel of the 
flower is the column, rather hidden by the other parts, but its apex is 
situated just above one side of the bucket, leaving a narrow opening betweea 
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