200 THE STORY OF PLANT LIFE 
The stem may be of three types, characters which 
serve to divide them up into three groups, and it is 
simplest in Ophrydez. 
The leaves are usually sheathing at the base, mem- 
branous, but may be petiolate, articulate, and hard, 
with no sheath, as in Vanilla; or they may be coria- 
ceous and have no veins, or membranous and strongly 
ribbed. 
The flowers are in three parts, with three sepals, 
three petals, the lowest spurred, the lateral ones 
different, the exterior labellum being anterior at first, 
the flower stalk twisting and curving. In the centre 
is the column of stamens and style, usually single, 
opposite the intermediate sepal, alternate with the 
petals. 
The column is often surmounted bya single anther, 
and in Cypripedium and Apostasia there are two 
stamens, and thus two groups are formed on this 
ground. Theanther is generally two-celled, but may 
be divided into three or four cavities. The pollen 
consists of lenticular or spheroidal grains singly or in 
pairs, threes, fours, etc., and is powdery or viscid, or 
raised in a mass on short stalks and held together by 
elastic filaments, forming an axis to which pollen 
adheres and the axis may be like a strap ora caudicle. 
The stigmaisa viscid hollow. The fruit isa capsule, 
three-valved, with three rows of seeds. 
The Orchids are more ornamental than useful. 
They have greatly decreased from the first cause in 
recent years. 
