(Read before the Horticultural Congress at Oxford, July 21, 1870).

Last year I had the privilege of reading a paper at the Manchester Congress of this Society "On the Improvement of Races," which subject may be said properly to belong to the "science " of gardening. To-day I have the pleasure of submitting to you my thoughts" On Colour in the Tree Scenery of our Gardens, Parks, and Landscapes; " and here I find myself dealing more directly with the "art" of gardening. While fully recognising the progress both in the art and science of gardening which has taken place in my day, I yet think that in this outlying but important province our professors have not made so free and effective a use as they might have done of the various tints of foliage which are to be found amongst trees and shrubs. Lest I should be misunderstood, permit me to state at the outset, that I hold the prevailing green with which the earth is clothed to be the best colour that could have been devised for the purpose, as blue is the most appropriate colour for the sky. But the sky, which is beyond our reach and power, is naturally subject to constant and considerable variation, and is singularly free from monotony. It is not altogether, or long together, of one colour.

There are light fleecy clouds continually breaking up the hemisphere of blue; varying in substance and colour; sometimes hanging motionless, but oftener sailing noiselessly along, more or less rapidly, and every moment changing in form. Then there are the dark thunderclouds, and the golden, silvery, purple, and roseate hues, which often give both life and brilliancy to the morning and evening sky.

But we have the power given unto us to vary and adorn the surface of the earth, and I would here invite public attention, and invoke the artist's aid in behalf of colour. There appears to me a monotony on the face of our English landscapes arising from one uniform and all-pervading colour - green. This monotony I would seek to remove by the introduction of trees with purple, white, and yellow leaves. With the same end in view, I would also plant more freely the transitory red, yellow, brown, and purple tints of spring and autumn, supplementing these effects by the introduction of berry-bearing trees - trees with white, red, black, and yellow berries, and trees with* white, red, and yellow bark for winter ornament. With these preliminary remarks I shall endeavour to show, 1st, that the object I seek is desirable; next, that it is attainable; and shall conclude with a few general remarks and brief examples in support of my views. I am free to confess that there is nothing in the whole range of nature which yields me more pleasure than the contemplation of a beautiful landscape.

To stand on some elevated spot in the English or Scotch lake district, for example, and look down on a broad and varied expanse of country; to row upon the surface of the lake, and look upwards upon the towering masses of rock and tree; to trace the lake shores, the lake islets and waterfalls, is, I believe, a recreation of a highly intellectual and more aesthetic order than the many who have not practised it might at first sight take it to be.

A highly-cultivated American gentleman once said to me: "England is a series of varied and improved landscapes. Now and then in remote districts one catches a glimpse of nature, unaided and adorned; but generally throughout the length and breadth of the land high art has been so skilfully applied as to effect the artist's object without leaving behind any traces of the artist's hand. But I miss the brilliant autumnal glow of the American forests: your landscapes lack colour." This very nearly expresses my ideas of English scenery; the natural beauties of our landscapes have in many cases been improved or developed at a sufficiently distant date, that the old and the new have become blended in one harmonious whole, leaving no strong lines of demarcation between the work of nature and the work of art; but the landscapes are generally cold and monotonous - wanting in variety and colour.

If we proceed to analyse a beautiful English landscape we shall find it composed of diversity of surface, light and shade, wood, water, rock, and many minor accessories, which may or may not be present, either singly or in combination. These I mention not to dwell upon, but to dismiss, as the recognised features of the landscape. My business at present is with tree scenery, and principally with one feature of it - colour. Our earth-tints are prominently neutral, often sombre; and to correct this should, in my judgment, be a leading idea with the true artist in landscape-gardening. A piece of country, however beautiful by nature - a garden, however perfectly planned - yields more or less pleasure according to the skill and taste exercised in the planting; just as the proportions and beauty of the human form are improved or otherwise by the style of dress - trees, shrubs, and flowers constituting, in fact, the exterior dress of the garden and the landscape. Now it must be patent to those even who are but slightly acquainted with this subject, that the labours of our plant-collectors abroad and plant-cultivators at home have placed within our reach many trees with coloured leaves - purple, yellow, and white - of various shades, and I hold that these colours should be so blended with the prevailing green as to remove the monotony which at present obtains.

That the effect of colour in the landscape would be generally appreciated, was once brought home to me in a peculiar manner. I was riding in company with some friends through the park at Chatsworth, in Derbyshire. Suddenly we sighted a tree with reddish-brown leaves rising from the greensward, and surrounded at some little distance with the usual green trees. Remote as it was, we could not at the moment make it out, but all admired it, and agreed that it was at once telling and beautiful. Led by admiration as much as by curiosity, we approached it, and discovered a dead tree retaining its reddish-brown withered leaves.