Cercidiphyllum japonicum

Last academic year I blogged about common trees and their seasonal attributes. This year I'm going to stick to picking out the occasional unusual tree, nothing very rare, but valuable for its particular features  at certain times. Something to surprise people with - something that could easily be more widely used.
This week Cercidiphyllum japonicum. I took these photos last week in Cheshire but have noticed the time of leaf fall varies between individuals of this same species in the local area. And its the leaf fall that is the key to this small tree. For not only do the Autumn colours include lime green, apple green, butter yellow and raspberry pink, sometimes on the same leaf, but their fragrance is astounding. As the heart-shaped leaves senesce and fall they exude an enticing scent of candyfloss and toffee apples. Even the fallen leaf litter continues to do this. Part of the romanticism of this tree is that the scent can be elusive - you might catch it on the breeze 20 metres from the tree but be unable to do so again with your nose right amongst the foliage.
It likes most soils but does not like drought, is fully hardy and will deal with anything but exposure to harsh winds. If you plant it somewhere confined its fragrance intensifies. Plant next to a path or in a front garden and passers by will love it, most especially for about three weeks every September.

Himalyan Balsam – Impatiens glandulifera - a call for action

If you are out and about looking at plants this week then just about wherever you are in lowland Britain (see defra website for map) you are likely to see this one. Whether you find yourself in a city, the countryside or speeding up the M6 – it will be there. It was introduced to the UK by Victorian plant hunters in 1839 and attractive though it may be it has a deadly combination of highly efficient annual reproduction through exploding seed pods and an easy monoculture, which it achieves by shading out other plants. Seed is projected some distance from the parent plant by the action of the ripening pod when touched or disturbed by the breeze. Add to this the very long season of seed ripening and dispersal – from June to October – and you have a potentially massive problem for our countryside, parks and gardens. The worrying thing is the speed at which this plant has become omnipresent. When I first started getting to know the Mersey Valley park in south Manchester – about 7 years ago – the banks and hedgerows were a mix of all the usual native annuals and perennials and shrubs. Now huge areas are dominated by this single species, with all the consequences this brings for diversity of plant and animal life. It is known to colonise canal and stream edges but this Autumn I have seen it in huge numbers in wetlands, on woodland margins, road embankments and field margins.

 Efforts have been made to control some of these populations but ‘balsam bashing’ is very labour intensive and does not begin to address the scale of this problem. The fact of seed spread by water, feet and tyres means that the answer can only lie with a central government initiative. The defra website will tell you it is an offence to plant it or introduce it in to the wild, but I would respectfully suggest that this is unlikely to make any impact whatsoever on its continuing spread.

If you want facts rather than my opinion have a look at the defra pages here. There are also local action groups listed through that site, though as these don’t join up and their activities are not governed centrally its hard to see what difference they will make.

Here are my photos showing the plant, flowers and pods before and after expelling their seed.