CaMBRIDGE, MassacnusetTtTs, Ocroser 5, 1938 Vo. 6, No. 8 
SAKBO COL, 
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BOTANICAL 
HARVARD UNIVERSITY 
| 6 1938 
RESUPINATION AS A DIAGNOSTIC 
CHARACTER IN THE ORCHIDACEAE 
WITH SPECIAL REFERENCE TO 
MALAXIS MONOPHYLLOS 
BY 
OakES AMES 
To our EYES there is something quite proper in the 
usual position of the labellum of an orchid flower. I sup- 
pose our demands for pleasing symmetry go as far as 
this, that the weightier parts should be the lowermost. 
(cf. plate of Cypripedium parviflorum opposite p. 146) 
Yet in the bulk of orchid species the labellum owes its 
satisfying position to a twist of 180 degrees in the ovary 
or pedicel, proof enough that it is in reality the upper- 
most member of the perianth, rendered the lowermost 
by some vagary of nature, or shall we say, by a sympa- 
thetic physiological response to the behavior of those 
food-seeking insects which accomplish pollination. 
In the bud of an orchid flower the labellum is adax- 
ial; in other words, it is adjacent to the axis of the in- 
florescence. If there were not any change in the pedicel 
or ovary up to and during anthesis, the labellum would 
remain adaxial. In orchids which have many-flowered 
racemes it is possible to observe the progressive turning 
of the buds as the pedicel and ovary twist, until in the 
expanded flower the labellum, by more or less pronounced 
curvature of the ovary near the base of the flower, be- 
[145 ] 
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