![]() ![]() The red is new: it’s being made in the leaf as the days grow shorter.Įvolutionary biologists have long pondered the phenomenon of the changing colours of autumn leaves. In particular, where leaves do become red in autumn, it’s not that the red pigments (anthocyanins, also the colour in blackberries) are simply being unveiled as the green of summer fades. ![]() It might be part of the story – and is certainly true of many yellow pigments – but it’s not all of it by any means. They are also more borer-resistant than most birches.Autumn’s changing colours in Wiltshire – timelapse video Guardianīut are those colours nothing more than pigments which have been there all along, and which simply become unmasked as emerald chlorophyll breaks down? That would be a very short rabbit hole – and this would have ended up a very short article indeed. River birch trees tolerate the summer heat better than paper birch trees, meaning they are better suited to grow in warmer regions. The trees' peeling bark is as attractive as the fall foliage. They can be multi-trunked trees or grown to have just one trunk. Native to the eastern U.S., they will reach a height of 40 to 70 feet with a spread of 25 to 35 feet. ![]() These specimens are full-sun trees, but they will also tolerate partial shade. River birch trees can be grown in planting zones 4 to 9. This refers to its bark, which starts salmon-colored but turns darker as it matures. An alternate common name is "black" birch, which is reflected in the species name, nigra (Latin for "black"). "River" birch is called so because, in its native habitat, it is often found growing near rivers. The Spruce Home Improvement Review Board. ![]()
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