This section is from the book "Handbook Of Hardy Trees, Shrubs, And Herbaceous Plants", by W. Botting Hemsley. Also available from Amazon: Handbook of hardy trees, shrubs, and herbaceous plants.
Within the last few years horticulturists generally have evinced an increasing desire to study the physiology and structural affinities of plants, as well as the art of growing them successfully. This has arisen doubtless from the fact that such knowledge tends to a clearer understanding of the laws governing the hybridisation of plants, and the great variety of forms they assume when subjected to artificial conditions. Not that botanical science is so far advanced as to be able to explain satisfactorily all the numerous phenomena of plant-life brought to light by cultivators. But much may be expected to result from the combination of science with practice. Experiments will be carried out in a more systematic manner, and the results more carefully recorded by those possessing sufficient knowledge to render their labours interesting beyond the commercial value or beauty of the varieties raised. Botanists can only theorise on many questions that gardeners have in their power to prove or disprove.