Redbud (Cercis canadensis) is a small tree, a size perfect for town gardens. It has so many wonderful features that it is a question as to why it has not been traditionally included in our landscapes. The reason for this “delay” is that it wasn’t included in most garden books which were primarily written by the British, and for some reason it was mostly ignored by those writers.
Its origin is as a woodland edge tree, so it has a rapid growth rate and makes beautiful arching limbs as it grows to fill in the open space it is planted into. It has lovely large, heart-shaped leaves (sometimes 20cm across) of a lighter green colour which creates a gentle effect—soft leaves on arching limbs. And then there are the beautiful reddish-pink blossoms which “jump” into spring as evocatively as the famous Flowering Cherry does each spring before leafing out.
But the Redbud is unique with its flowers spaced along old and previous years’ wood—very unusual, as for most plant species the flower buds are created on last year's growth to be nearer the sun. Because Redbuds flower before the surrounding forest has leafed out, the winds can spread the pollen easily and the “effort” to form flower buds is achieved through regeneration on existing bud structures.
Whereas most trees flower on the previous year’s and/or the current year’s new growth, the Redbud flowers on even older wood. Young seedlings are sometimes found near the tree and so succession occurs naturally—or we can offer a transplant gift to our neighbors!
Another special feature is that it is a tree which is self-pruning. Each spring, on the underside of the arching canopy, you will find branches that
have been aborted over winter. This makes pruning decisions quite easy as it is simply a matter of firstly recognizing and then trusting that the plant understands where it can collect the most light in the approaching season.
These internal limbs will be shaded out by the rapid and newly growing upper canopy, and so the tree recognizes that it would be “efficient” to withdraw sap now and seal off the whole branch at its base from where it once emerged a few years ago. This natural sealing process means few diseases enter through the old connection, as the cambium rapidly covers over the open woody material of the trunk.
The tree “knows” its circumstance and that having to compete for light against much bigger trees means it must focus growth only where light is most available—it is naturally its genetic history which enables such an unusual adaptive feature. And so, with amazing brightly coloured flowers early in spring, followed by pea-like pods hanging throughout the winter, rapid growth, and a lovely self-maintaining arching form, this small tree will become a welcome feature of most landscapes within our cities and in any other scenario we can imagine. A treasure of a tree!