STRUCTURE OF FLOWERS 7 
extinct, is the next step, the labellum being formed into a 
pouch with infolded side lobes. The column has a promi- 
nent staminode with two fertile anthers below it, one on 
each side of the column and behind the stigmatic plate. 
The upper sepal is frequently the showiest feature in the 
flower ; the lower sepals are joined and arranged behind 
the lip, whilst the petals extend on each side and vary 
much in form. 
In gardens, the whole of the genus is known as Cypri- 
pedium, although the South American species (Seleni- 
pedium), having a three-celled ovary, differ widely from the 
one-celled East Indian and Malayan species, and other sec- 
tions have such marked and consistent botanical differences 
as to warrant the botanist in separating them under dif- 
ferent sub-generic names. The third section of Orchide, 
the largest family of the Monocotyledons, forms the chief 
class of Orchids as they are known in gardens. In this 
class the stamens and style unite into a column, and at the 
top of the column the pollen masses are situated ; these are 
covered by the anther-cap, and in a cavity is the stigma 
with its viscid surface to receive the pollen grains. 
So diverse and intricate are the forms of the flowers, and 
especially labellums, that there is little doubt that insect 
aid is necessary in their natural habitats to bring about 
pollination. It has been proved by the operations carried 
out in cross-fertilisation in gardens that no class of plants 
can be so readily crossed under artificial conditions. It is 
not necessary here to go further into structural details, as 
the peculiarities of each section will be remarked on under 
their different headings. But it may be said that in what 
are called abnormal flowers, which have perfect stamens 
