Tae’ owe ee ee ee 
4dHIE ORCHID REVIEW, 
VoL. XX.] AUGUST, tog12. (No. 236, 
EVOLUTION OF THE ORCHIDACEZ., 
(Continued from page 207.) 
Our last paper completed the review of the different groups of Orchids, 
and it now remains to show some of the steps by which they have reached 
their present development. On this we can obtain no help from geology, 
the only fossils suspected to belong to the Order being of entirely doubtful 
origin. Weare thus limited to the evidence obtained from existing forms, 
which is fortunately extensive. We have seen that the two principal 
characters, the aggregation of the pollen grains into pollinia and the 
modification of one of the three stigmas into a rostellum, are not universal 
characters, being absent from the suborder Diandre, so that the Order is 
less isolated than might at first appear. 
Taking existing Orchids as a guide we may safely infer that the 
ancestral representatives of the Order were terrestrial monocotyledons, 
with an inferior, three-celled ovary, numerous minute seeds, having a 
reticulated seed-coat and rudimentary embryo, and the stamens and pistils 
not yet aggregated intoacolumn. The flowers were, doubtless, fertilised by 
insects, which, on visiting the former, would become dusted with the pollen 
grains from the anthers, as in the case of other entomophilous monocoty- 
ledons. We may also infer that ancestral Orchids were natives of the great 
tropical forest region. The characters mentioned are found in the Malayan 
genus Neuwiedia, the most primitive of existing Orchids. The species of 
Neuwiedia have short, erect stems, with a tuft of plicate, Curculigo-like 
leaves, and an erect spike of yellow or white flowers, with a nearly regular 
connivent perianth, and three linear or oblong anthers, borne on one side 
of the flower, free pollen grains, and a slender, nearly free style. 
From this point we can trace the progressive modifications of structure 
until the culminating point of development is reached. Taking the first 
tribe Apostasiez we find the third stamen of Neuwiedia reduced to a linear 
staminode in Apostasia, and totally suppressed in Adactylus, both being 
accompanied by a change in the shape of the inflorescence. In Cypri- 
pediez we find the same essential type, but the perianth has now become 
irregular. the lip modified into a pouch-shaped body the third stamen into 
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