angraecoid orchids of Africa, as well as in 1926 his sys- 
tem of orchids in which he assembled and arranged all 
genera according to his interpretation of their phyletic 
affinities. Since that time the only noteworthy contribu- 
tion to monopodial orchids was by Dockrill who, in 1967, 
published the results of his investigations on the sarcan- 
thine orchids occurring in Australia. It should be noted 
that none of the genera and species native to the main- 
land of Asia and India have been studied and brought 
into line with the others except those from Thailand by 
Seidenfaden, who has recently published some extremely 
valuable data. 
Systematic Trends 
No other group of orchids representing a distinct ana- 
genetic line can be compared with the monopodials re- 
garding the overwhelming diversity found both at the 
specific and generic levels. This group is one of the 
youngest branches in the family, and I believe it is still 
in a rapidly expanding evolutionary flux. Since in the 
orchid family reproductive isolation is achieved primarily 
by other methods than genetic incompatibility, the 
characterization of species and genera must be extrapo- 
lated from the available morphological data. It was 
Lindley, while preparing his Genera and Species of 
Orchidaceous Plants, who recognized the fact that the 
generic criteria in this branch of the family are located 
primarily in the flowers, especially in the construction 
of the lip with the position of its callosities and excres- 
cences. Their patterns he observed through longitudinal 
sections. The reliance upon such seemingly trivial charac- 
ters, or rather the lack of understanding of them, was 
the primary cause that has contributed to the systematic 
chaos in this group which has been partially described 
above. Yet the significance of such minutiae, as described 
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