“ap 
® 
TH bet) RTD ‘REVIEW. 
Vor. XVIII.] fNo. 206. 
FEBRUARY, Igi10. 
THE EVOLUTION OF THE ORCHIDACE., 
(Continued from vol. XVil., page 356.) 
Our last paper brought us to the large and polymorphic Habenaria group, 
which is now divided into two subtribes, Gymnadeniez and Habenariee, 
the former having one, and the latter two distinct stigmas. Gymnadeniez 
chiefly differs from Serapiee in having the glands of the pollinia detached 
from the surface or end of the rostellum, without any enclosing pouch. In 
fact the genus Gymnadenia closely resembles Orchis, except for the differ- 
ence just pointed out. 
Platanthera is the largest genus in the group, numbering over 50 species 
and is very widely diffused through the temperate regions of the northern 
hemisphere, with a few tropical representatives. This and Gymnadenia are 
sometimes united with Habenaria, but such an arrangement ignores the 
great and striking difference seen in the rostellum and stigma, besides making 
Habenaria into one great chaotic aggregate whose characters cannot be 
defined with any degree of precision. Herminium is a small European and 
North Asian genus, bearing spikes of small green flowers, with a very short 
spur to the lip. Holothrix is exclusively African, and contains some 30 
species, in which the petals and lip are invariably longer than the sepals. 
Other exclusively African genera are Brachycorythis, Schizochilus, 
Huttonea and Bartholina. Huttonza is remarkable for its broadly 
spathulate, much fringed petals, and Bartholina for its single-flowered 
scapes and fan-shaped, much-dissected lip. Bartholina pectinata is 
occasionally seen in cultivation, Arnottia and Bicornella are small 
Mascarene genera not known in cultivation. Hemipilia is from India and 
China, and is characterised by its single broad leaf and spikes of purple, 
Orchis-like flowers. H. amethystina has a beautifully spotted leaf, and is 
known in cultivation. Two or three other small genera are sometimes 
recognised as distinct. The species are terrestrial, and approach Orchis 
and Habenaria in general appearance. The flowers are green, white, 
purple or rarely yellow. 
The fertilisation of various species of Gymnadenia and Platanthera has 
been studied. Darwin points out that Gymnadenia conopsea resembles a 
33 
