Cotinus coggygria 'Royal Purple'

Autumn colour range in single specimen of Cotinus coggygria 'Royal Purple', Manchester 18.11.2012

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.

Tree of the Week

Week 18; Prunus cerasifera var. atropurpurea

Its a bit of a mouthful, but this is a great tree as a dark backdrop for shrubs with bright foliage or flowers. I've chosen it this week because I spotted it in a local garden with a lime-green leaved Philadelphus coronarius 'Aureus' in front of it, and the contrast was eye-catching to say the least. Its deciduous, flowers in March and is quite small and slow-growing, which is often useful. In time it could reach 12m high, but you rarely see them that big in these parts. Its compact and well-behaved, needing a reasonable amount of sun. The wild species is green.

Philadelphus coronarius 'Aureus'  

Tree of the Week

Week 17 - Tilia cordata; Small-leaved Lime

The tricky thing with identifying Limes is that unless you have a small-leaved one growing right next to a large-leaved one (Tilia platyphyllos) for comparison, then how can you be sure how big the leaves are? Then there is the Common Lime (Tilia x vulgaris), which is a hybrid between the two and, well, common. My chosen one this week, though, is distinct because it has downward-arching branches rather than upward, and upward-angled flowers rather than drooping ones like the other two (see below). Often found in woodland on limestone and also as a street tree because it is pollution tolerant. In this context aphids usually attack the tree and suck its sap, excreting sticky 'honeydew' (nice word for aphid poo) all over the cars below.
It is in flower right now, but they are very subtle blooms, so you will have to keep a sharp eye out.

Tilia cordata flower - not-so-downwards...

Tilia platyphyllos flower - definitely downwards

Tilia cordata leaf

Tilia cordata form

Tree of the Week

Week 16 – Sambucus nigra; Elder

This week I’ve seen the first elders in flower, the late May sun bringing them out in a warm south facing hedgerow.  In this context they are more like a large shrub than a tree, but they can grow to 10 metres in the right conditions. They prefer rich damp soils and often grow on disturbed soils. The form is very variable, sometimes with a main trunk and other stems growing up from the base, or sometimes just multi-stemmed. The flower head is roughly circular, about the size of your spread hand, made up of many tiny white flowers. Smell the flowers to confirm the identification – unsurprisingly the scent is of elderflower cordial, although different specimens seem to yield varying strengths of aroma. Leaves are oval, pointed at the end and with toothed edges and held in opposite pairs along the leaf stalk, with one leaflet at the end. The twigs are bumpy and the bark deeply grooved. The berries will be green ripening to black and used to make wine. A tough and very attractive native.

The Kew website will tell you everything else.

Tree of the Week

Week 15 - Fagus sylvatica; Beech

Couldn't resist it. A personal favourite, Fagus sylvatica is in its prime this week with the intense yet soft green of the new foliage, as ever the stone-grey smooth bark and majestic trunks rising high in to the canopy...I'll have to stop there before I overdo it. It likes a well-drained soil. Autumn colour is a buttery yellow. On a young specimen or clipped hedge the browned leaves will stay on over winter. If you're not sure about identification then look on the ground, and whatever the time of year you are likely to find seed cases, spiny though not sharp like a conker case, and about the size of a Cadbury's mini egg, maybe a bit bigger. Enjoy.

If you want to immerse yourself in the Beech, then read 'Beechcombings' by Richard Mabey, review here.

Tree of the Week

Week 14 – Sorbus aucuparia; Rowan, Mountain Ash

Fresh in to flower now, with rounded white flower heads about the size of your hand but made up of many tiny flowers. They have red berries in Autumn, which are valuable for birds. In a cold winter they will have some Autumn leaf colour too. Useful because of their tolerance of cold winds, small size (usually about 10m) and the fact that they tolerate light, poor soils and dry conditions. The leaves are quite distinctive and a good way to check your identification – they are composite (made up of many small leaflets) with the tooth-edged leaflets held in opposite pairs along the central twig. Other Rowan species and S. Aucuparia varieties are available, with orange, pink, white or yellow berries.

n.b. a close competitor for tree of the week this week was copper beech, their leaves are so newly out that they are green/pink/red all at once and look amazing in Manchester at the time of writing. Copper beech is of course not its proper name, find out why here.

Tree of the Week

Week 13 – Larix decidua; Larch

Chosen this week because of the “new bright green needles combined with distinctive cones” (thanks, Alice) Larch is a great conifer for a number of reasons. As it is deciduous you get the benefit of seasonal change but with the aesthetic qualities of a conifer. The new leaves are held in soft tufts along the twig, interspersed with upright pink female cones which look a bit like tiny pineapples. The  yellow male cones are smaller, drooping down. The twigs are very knobbly, though this is more obvious in winter, and the autumn colour is a bright yellow, often dominating a hillside. They are native to mountainous regions in central Europe and do well in similar terrain here. Form is reliably fairly conical and mature cones are about 3cm long, scaly, egg-shaped and woody. Fast-growing and of course used widely for timber, but currently threatened by Phytophthora ramorum, about which you can read more on the Forestry Commission’swebsite.

Tree of the Week

Week 12 – Malus sylvestris; Crab apple

In my opinion this has the most appealing of all the Spring blossom, alongside its edible relative Malus domestica, because of the very delicate pink-white hue. Most apple trees have this colour as they are not the truly wild pure white species, but crossed with M. domestica. They are at their peak now in Manchester, though today’s stormy weather hasn’t done any of the blossom any good.  The leaves are just about unfurled, and are rounded ovals with toothed edges and pointed end. At this time of year the leaves are downy. Bark is grey-brown, and on a mature specimen quite scaly and cracked. Form could be very variable so the below winter skeleton is just a guide.

There are many ornamental cultivars, with bright red, yellow or orange fruits. Beware of planting these over paving as the fallen fruit makes a slippery mess in the autumn. Look at the (probably) infallible RHS website for more on these.

Tree of the Week

Week 11 – Pyrus communis; Common Pear

This wild pear produces small sour fruit with a gritty texture – the pears we eat are a related variety. Pear trees can be found in hedgerows and field margins and are sometimes domestic ‘escapes’ or remnants of old orchards. This tree is deciduous, 8-20 metres tall, somewhat spiny and in flower now, as are most domestic pears in our gardens and allotments. The blossom, below, is simpler than most cherries, with five white petals and reddish stamens. Leaves, also below, with fruit, are slightly glossy and with a serrated edge. The other wild pear, Pyrus pyraster, now uncommon, is similar but with more spines along the twigs, and the fruit is smaller and even less edible. For a good ornamental pear tree, check out Pyrus salicifolia (meaning leaves like a Salix – ‘willow leaved’) pendula and Pyrus calleryana ‘Chanticleer’, both of which blossom well and have distinctive forms.

Wikipedia has a good article about Perry, here.

Pyrus salicifolia 'Pendula'

     
          

             Pyrus calleryana 'Chanticleer'

Tree of the Week

Week 10 – Salix sepulcralis Chrysocoma; Weeping Willow

Weeping willow is fairly easy to identify due to its size and distinctive form. You will have noticed that it loves moist soil and so grows on river banks and pond edges, with the long weeping branches often brushing the surface of the water. For a couple of weeks now it has been eye-catching because the fresh new leaves are such a vivid green and the domed form of the whole tree suddenly stands out against slightly later-leafing species. It reaches about 12m high in 25 years. Catkins are also out now, longer and more slender than the Goat Willow catkins, see picture below.

The roots will seek out water so plant well away from drains, mains water pipes and septic tanks. Not native, but completely hardy, this tree makes quite a grand impression in parks and grounds.

Ashridge nurseries are a reliable source of information about trees, read more about this tree here; www.ashridgetrees.co.uk/Weeping-Willow-Trees-Sepulcralis.

Tree of the Week

Week 9 – updates!

I am on holiday this week. I’m not abandoning you, though – instead of a new tree, here are some updates on trees you have already identified, and what they are doing in the UK right now. Look out for them and see if you can still get them...

Aesculus (Horse Chestnut) leaves unfolding and flower buds emerging

Crataegus (Hawthorn) leaves out and flower buds visible

Fraxinus excelsior flowers, with last year's keys still hanging on and leaf bud visible

Tree of the Week

Week 8 - Flowering  Cherries (Prunus spp.)

A departure for Tree of the Week this week, with almost a whole genus rather than a single species of tree. I’m just being indecisive because on the streets near you right now, looking ridiculously cheerful, are so many flowering cherries of various kinds it is not realistic to choose just one. There are many varieties and they have been on our shores since the early twentieth century, with the exceptions of two natives; the bird cherry – Prunus padus, and Prunus avium, the wild cherry. Prunus avium is more common in the south of England and Prunus padus, preferring wetter and more acidic soils, in the north. They aren’t keen on cold winds and the blossom only looks amazing for a few short weeks, but you have to admit that for that time they really do the business.  Most also have great Autumn colour, in yellows and bright reds, so this isn’t the only season of interest. It can be hard to tell one from another. Almond and blackthorn blossom are both similar (both also Prunus), but you won’t mix these up as cherries always have those oval or linear horizontal markings on the bark of the trunk, which are the lenticels through which gas exchange occurs between the plant’s tissues and the atmosphere, see examples below.

Prunus padus

Prunus avium