364 THE ORCHID REVIEW. 
THE STRUCTURE OF AN ORCHID FLOWER. 
The majority of Orchid flowers are so complex in structure that it is by 
no means an easy matter to make out the exact plan on which they are 
arranged. Microscopical examination, however, has shown it to be a 
modification of the monocotyledonous type, as all the organs of a typical 
monocotyledon—a lily, for example—have been traced in one form or 
another in the flowers of different Orchids, and the curious malformations 
which from time to time appear frequently afford some striking confirma- 
tions of this theory. A few remarks on the subject may therefore be 
interesting to readers of the Orchid Review. : 
The two principal characters in which an Orchid flower differs from that 
of a typical monocotyledon are, the modification of one of the petals into 
an organ called the lip, and the consolidation ot the sexual organs into a 
central column. The plan is the same in each case, though the details are 
so different. This plan is shown in the annexed diagram, which will 
enable the following remarks to be understood. 
Dorsal *. sepal 
AI 
Petal RY Petal 
ay RST Hix 
Ags Gee 
Lateral * sepal “ { Lateral * 
Lip 
DIAGRAM ILLUSTRATING PLAN OF ORCHID STRUCTURE. 
The asterisks in the above diagram represent the fifteen organs of 
which a monocotyledonous flower is composed, and which are arranged in 
five alternating whorls of three each. The outer whorl consists of three 
sepals, the second whorl of three petals, the third and fourth of an outer 
and an inner row of stamens, six in all, and the fifth or central one of three 
carpels, which are generally confluent. In an Orchid flower all these are 
either actually or potentially present, though owing to the amount of 
cohesion which has taken place the fact is not at first apparent. Each of 
these organs is supplied with a central fibro-vascular bundle, or cord, and 
if these are traced back to the pedicel it will be found that they arise from 
six groups of cords, arranged in a single circle, three of which divide each 
into three radiating branches, and the remaining ones each into two, 3 
making fifteen in all. Taking these groups individually it will be seen that | 
the one-which feeds the dorsal sepal sends also a branch into A 1 (the only 
stamen of most Orchids, and the staminode of Cypripedium) and into sT 
(the lobe of the stigma which is modified into the rostellum). In a similar 
