one is almost always very dissimilar both in size and 
shape, and is known as the ‘‘lip’’ or ‘‘labellum.’’ Next 
are two whorls of stamens, which present definite vari- 
ations of expression in the two great subdivisions of the 
family, Diandrae and Monandrae. In the former, the two 
lateral stamens belonging to the inner whorl are function- 
al, and the median one of the outer whorl is represented 
by a conspicuous staminode, which assumes various 
shapes. No indications of other staminal members can 
be made out externally. In the Monandrae, on the con- 
trary, the median stamen belonging to the outer whorl is 
the functional one and no indications of the other stami- 
nal members are to be seen externally. In both groups 
the next and innermost whorl consists of three stigmas ; 
in the Diandrae, all three are usually functional, whereas, 
in the Monandrae, only the two lateral are functional, 
the median one being modified as the rostellum. Further- 
more, it may be noted that the stamens and stigmas in 
the Diandrae are almost ‘‘free,’” whereas in the Monan- 
drae they are united into a central pillar-like structure, 
which has come to be known by the names ‘‘column”’ or 
‘‘oynostemium., ” 
In the present text and the accompanying figures | am 
using the following terminology and symbols for the 
various parts of the orchid flower (reference to Fig. 1 
may be made): 
Outer whorl of perianth Dorsal sepal DS 
Lateral sepals LS 
Inner whorl of perianth Median petal (labellum) MP 
Lateral petals LP 
Outer whorl of stamens Median stamen Al 
Lateral stamens A2 and A$ 
Inner whorl of stamens Lateral stamens al and a2 
Median stamen a3 
Whorl of stigmas Median stigma Gl 
Lateral stigmas G2 and G3 
[ 64 | 
