The order Gramineae (Grasses) is very extensive, containing more than forty British genera. They are, however, wind-fertilised.

This is the last order which I have to mention. Those who have done me the honour to read so far, will not need to be told that this little book is fragmentary and incomplete. For my own part, I am only too sensible of it. Nevertheless, the fault is not altogether mine. Our knowledge of the subject is as yet in its infancy; and indeed, my great object has been to bring prominently before my readers how rich a field for observation and experiment is still open to us. Most elementary treatises unfortunately, though perhaps unavoidably, give the impression that our knowledge is far more complete and exact than really is the case. This naturally tends to discourage, rather than to promote, original observations. Few, I believe, of those who are not specially devoted to zoology and botany have any idea how much still remains to be ascertained with reference to even the commonest and most abundant species. In the present case, I have confined myself to the consideration of Flowers in relation to Insects. The interesting adaptations presented by such forms as the grasses, conifers, etc, which are fertilised by the action of the wind, did not therefore come within my subject.

The causes which have led to the different forms of leaves have been, so far as I know, explained in very few cases: those of the shapes and structure of seeds are tolerably obvious in some species, but in the majority they are still entirely unexplained; and even as regards the blossoms themselves, in spite of the numerous and conscientious labours of so many eminent naturalists, there is no single species as yet thoroughly known to us.