CHEESEMAN.—On the Fertilization of the N.Z. Pterostylis. 353 
so strongly marked in /terostylis, that I have ventured to draw up the 
following account of my observations on that genus. I have been the more. 
induced to do this from the fact that Mr. Darwin’s book “ On the Fertilization 
of Orchids,” which is deservedly considered to be the standard work on the 
subject, does not contain an account of a similar method of fertilization ; nor 
is any species described, included in the sub-order Arethusee to which 
Pterostylis belongs. 
The genus Pterostylis is represented in New Zealand by seven species. 
Of these, six (P. banksii, P. graminea, P. micromega, P. foliata, P. trullifolia, 
and P. puberula,) constitute a closely connected series of forms, and seem to 
present no differences of importance in their fertilization. The seventh species 
(P. squamata) belongs to another section of the genus, and (judging from 
descriptions) differs in several respects from the others. It is stated in the 
“ Handbook ” to have been discovered near Auckland by the late Dr. Sinclair, 
but I have not been fortunate enough to find it, nor has the plant been seen 
by any New Zealand botanist of late years. I shall now proceed to describe 
the mode of fertilization in P. trullifolia, the species on which my observations 
are the most complete. The accompanying illustration (Pl. XX.), containing 
magnified drawings of the most important parts of the flower, will perhaps 
cause my meaning to be more easily understood. 
The upper sepal and petals connive and form a kind of hood, inclosing 
and arching over the column. The lateral sepals are placed in front of this 
hood, and being united for fully half their length, partially close the entrance 
to it. The column (see figs. C. and D., and c. in fig. B.,) is bent backwards at 
the base, so as to lie close to the upper sepal, with which for some distance it 
is united ; it then becomes erect, and towards the summit is furnished with 
two broad membranous wings, each of which is extended downwards into a 
blunt lobe, and upwards into an erect horn-like appendage. The stigma (s. in 
Figs. C. and D.) isa bilobed prominence about the middle of the column. The 
anther (a., Figs. C. and D.) is terminal, hinged on to the summit of the column, 
two-celled, the cells opening while the flower isstill unexpanded. The pollinia 
(p., Figs. D. and E.) are four in number, two in each cell, linear in shape. They 
lie loose in their cells, having no caudicles, and do not become attached to the 
rostellum. The rostellum (r., in Fig. D.) is an erect, somewhat triangular 
projection, placed immediately below the anther. Its anterior surface is 
slightly concave, and consists of a thick mass of highly viscid matter, portions 
of which can easily be detached. 
The lip, consisting of a linear, somewhat fleshy lamina, with a curious 
curved appendage at its base, is clawed on to the bottom of the lateral sepals 
by a delicate ribbon-like membrane. It is extremely sensitive, so that, 
although in its natural position it has its apex exserted between the free 
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