450 VEGETABLE PHYSIOLOGY 
insects. The Plantains also afford instances of the replace. 
ment of the one method by the other. 
Anemophilous flowers exhibit certain structural features 
which are associated with their mode of transference of 
the pollen. It is produced in such flowers in great abun- 
dance, is extremely light and dry, and in some cases is 
furnished with bladders to aid its transport. The receptive 
organ is in some cages a bulky cone, the leaves of which 
are separated from each other, and from the common axis, 
by spaces into which the pollen may drop. In others it is 
a much-divided or plumose stigma, often furnished with 
hairs, so that pollen falling on it may be readily retained. 
The method, however, is a wasteful one and involves the 
production of a superabundance of pollen. On the other 
hand anemophilous flowers are always inconspicuous and 
of a comparatively humble type. 
Flowers which are pollinated by insects are usually 
much larger and more showy ; they not infrequently possess 
irregular corollas, and are often very highly coloured and 
provided with characteristic odours. Their perianths, and 
sometimes their sporophylls, are highly modified to adapt 
them to the habits of their insect visitors. As a further 
attraction to the latter they usually produce honey in some 
part of the flower, the nectary, in such a situation as will lead 
to the removal of pollen by the insect in its search for the 
attractive liquid. The markings on the coloured perianth 
leaves are often arranged in such a way as to direct the insect 
towards the spot where the honey is concealed. The pollen 
itself also is often the object of the insect’s visit. Many 
special mechanisms to secure the removal of the pollen from 
the microsporophyll and its deposition on the stigma of another 
flower are to be met with; indeed, almost every Natural 
Order shows some modification of the structure of the flower 
in this direction. The consideration of them in detail, 
however, is beyond our present purpose. 
Something akin to cross-pollination occurs in one of 
the Hydropteridee, a family of Ferns with an aquatic habit. 
