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There is a mystery about the autumn colouring of the foliage of our many beautiful hardy trees and shrubs in this country, and we have never yet ascertained with any degree of exactness the conditions that produce the richest and brightest tints. Probably the conditions most favourable generally are provided by a good growing season—that is, a warm, moist summer—followed by a dry, sunny autumn. But it frequently happens after what one would regard as favourable seasons, that species which are usually quite trustworthy in this matter fail to colour well. Probably one set of conditions does not suit all trees and shrubs in this respect. To produce the colouration of the leaf just before it falls certain subtle chemical changes in its composition take place. And to bring about these changes certain conditions in regard to sunlight, temperature, and moisture are necessary. But in a climate such as that of Britain, where the seasons are never alike two years together, we can never hope to obtain the same regularity of autumnal colouring that characterises the vegetation, for instance, of the Eastern United States. Still, when all is said, we possess in our gardens a large number of trees and shrubs and climbers that are delightful in their autumnal livery of crimson, purple, scarlet, or gold. It is curious that every season we may notice species not usually conspicuous for their autumn tints beautifully coloured.

An over-vigorous, sappy growth, often the result of a wet, warm autumn or too rich a soil, is certainly detrimental to autumn colouring. Rhus cotinoides, an American Sumach, worth growing for the beauty of its colours in autumn, is one of the most unfailing in this matter. This is perhaps one of the loveliest of all autumn-tinted shrubs, and should be more planted. But young plants, put out in well-trenched, heavily-manured soil, will often fail to colour at all till they get older and less vigorous. The most beautifully coloured examples of this Sumach that we have seen grow in rather light sandy soil. We have frequently noticed, too, that various species of Vine (Vitis) when starved in pots will colour exquisitely, whilst others, planted out in the ordinary way, completely fail. We believe, therefore, when planting with a view to the production of autumnal colour, any great enrichment of the soil is neither necessary nor advisable, provided it is of moderate quality to start with.

In the following notes, brief mention is made of some of the best trees, shrubs, and climbers that colour in autumn:—