Search Results for: Birch

Rowan berries are relished especially by thrushes and other bigger songbirds. One bird that is very fond of them is the waxwing (Bombycilla garrulus).

It breeds in Scandinavia but, if rowan berries become scarce in its homeland in winter, it comes in large flocks to the UK and Ireland to feed on Rowan and some other, especially red, fruits. It can eat two or three times its own body weight in a day.

Aucuparia means “bird-catching”. Rowan was used in the past to create birdlime used in the unfortunate practise of trapping songbirds for food.

Rowan berries are relished especially by thrushes and other bigger songbirds. One bird that is very fond of them is the waxwing (Bombycilla garrulus). It breeds in Scandinavia but, if rowan berries become scarce in its homeland in winter, it comes in large flocks to the UK and Ireland to feed on Rowan and some other, especially red, fruits. It can eat two or three times its own body weight in a day.

Shield-bugs relish its berries as well. They are even edible to humans, are rich in vitamin C, but people should be careful of eating it raw in large quantities as it contains parasorbic acid, which is slightly toxic, but breaks down into non-poisonous compound when cooked.

Leaves

Leaves are composed of 6-8 pairs of small leaflets, each 3-6 cm long and toothed at the edges.

They are usually hairless, dark green above and grey-green below. The leaflet at the tip is never larger than the rest. The leaves turn yellow and red in autumn and often stay on the tree into November.

Flowers

Flower heads are creamy white. Each flower has 5 petals – like the flowers of other members of the rose family. They are arranged in flat, branched clusters about 10cm wide, usually.

The flowers appear from May to June. They have a very distinct smell that attracts flies, beetles and bees. These help to transfer the pollen from one flower to another.

Fruits

Fruits are almost round, fleshy red berries, up to 10mm across. They are orange at first, with yellow flesh.

They ripen in September and each has between 2 and 8 seeds (usually 3 or 4). Each fruit has a tiny “star” in the middle which is a remnant of the calyx and reminds us, that it belongs to the same family as dog rose.

Seeds are dispersed by birds, that’s why we sometimes find so-called “flying rowans” in unreachable places, eg. in the crown of another tree, like oak.

Bark

The bark is smooth, shiny and grey. Winter twigs are grey with hairy buds (especially when young). The wood is dense, hard and pale brown. It is used for turnery, carving and is good for firewood.

Together with Yew, it was used in the Middle Ages for making bows.

Habitat

Rowan is a deciduous tree. It is very frost-hardy, wind-resistant and has deep roots, so can grow even in rocky crevices. It tolerates poor, thin, acid soil.

Rowan also colonizes bare ground together with birch and grows at a higher altitude than most other deciduous trees. Unlike downy birch, it doesn’t form woodlands on its own and can’t tolerate waterlogged sites.

Once our seeds have germinated they are reliant on us to ensure a steady supply of water and food. We must also keep them free from weed competition and any pests and diseases that may threaten their growth.
Position

Our native trees do not like high temperatures, but they will benefit from a certain amount of protection from the elements. If grown in containers, this can be achieved by placing the pots on a windowsill, in a polytunnel or another such place. Wherever they are though, please ensure that they receive plenty of bright light. Otherwise they will grow weak and spindly. If they are grown in seedbeds, there is no option but to grow them outside, unless you are lucky enough to have a greenhouse or polytunnel.

Watering

Too much water can be as damaging as too little to our young trees, especially to those grown in containers. Obviously, we have less control over the amount of water our trees receive outside and we must hope that Mother Nature sends us just about the amount we would ask. We can add extra when she doesn’t send enough, but must hope that our soil is well-drained enough to cope with those times when she is a little ‘over generous’.

Weeding

Competition from weeds can seriously reduce the growth of our trees. Weed growth in containers can be kept to a minimum if sterile compost is used, but take care to remove any weeds that do appear! They will grow very quickly, especially when the pots are undercover. Weed growth outside will be slower, but they will inevitably overtake and possibly smother our trees if they are given the chance. Weeds are best carefully removed when they are very small. This will cause the minimum disturbance to the trees’ delicate roots.

Feeding

The photograph on the right shows, quite starkly, the difference between young hawthorn seedlings that are short of food (on the left) and those that are well-fed (on the right) – and these are real photographs! Plant nutrients in the soil can quickly ‘leach’ with heavy rain leaving plants short of food. While they may recover as their roots develop, they will have suffered a setback for that year, resulting in smaller seedlings.

The best way to feed plants is to do it indirectly by feeding the soil. Due to leaching or a high demand from many seedlings, this may not always be adequate. As a supplement there are many proprietary brands of fertilizer available, organic and inorganic. Our trees require a well-balanced fertilizer to be applied little and often (perhaps every 4-6 weeks). This may be in the form of a liquid feed (particularly good for containers) or granular, which will leach more slowly. Never apply more than is recommended as this can damage the plants’ roots and have an adverse effect on our environment.

Pests and diseases

Perhaps the biggest threat to the health of our young trees is that from pests and diseases. These can strike at any time – from before seed germination all the way through to mature plant. The amount of damage they will do generally depends on the overall health of the plants being attacked. A healthy plant can resist pests and diseases far better than an unhealthy one.

The main pests and diseases that we come across on trees are:

• Mildew on oak, hawthorn, purging buckthorn and crab apple
• Rust on birch
• Blackfly on wild cherry
• Scab on rowan

How we treat pests and diseases will depend on our general approach to gardening. Organic gardeners will have fewer methods of control at their disposal than do gardeners who are prepared to use pesticides. Garden centres should stock a range of treatments, both organic or otherwise, that we can use once we have identified the problem. But, keep your eyes wide open! The earlier we spot any kind of problem, the earlier we can treat it and the more effective the treatment will be. Check out the Garden Organic for organic solutions.

Dormancy

A mature, live seed, which will not germinate promptly when placed under suitable conditions, is said to be dormant.

The mechanisms that prevent germination vary widely and it is not necessary to understand them to grow trees from seed successfully. What is important for us to understand is how we can get these dormant seeds to germinate.

Overcoming dormancy

Relatively simple and effective methods exist to overcome the dormancy of our tree and shrub seeds.

The most common requirements are exposure to periods of warmth and/or cold.

The simplest method of providing these conditions is to place the seeds outdoors, mixed with a moisture retentive and aerated medium (usually a sand/compost mixture).

Seed pretreatment

In order to be successfully treated seeds must be moist. Seeds that are placed into treatment immediately following extraction will require no further processing.

Seeds that have been stored for any length of time will require soaking in water for 24-48 hours. Soaking dried seeds performs two functions. Firstly, the seeds take up water and, secondly, some of the germination inhibitors in the seed coat are removed.

Seed pretreatment summary

The typical time periods of warmth and cold needed by seeds of different trees. These periods help overcome dormancy and, without them, many seeds simply wouldn't germinate.

More details and the recipe to grow each tree can be found by clicking on the name of the tree.

Species	Latin name	Warm (weeks)	Cold (weeks)
Common alder	Alnus glutinosa	0	4
Silver birch	Betula pendula	0	4
Downy birch	Betula pubescens	0	4
Hazel	Corylus avellana	0	12-16
Hawthorn	Crataegus monogyna	4-8	12-16
Broom	Cytisus scoparius	0	0
Spindle	Euonymus europaeus	8-12	8-16
Beech	Fagus sylvatica	0	4-20
Alder buckthorn	Frangula alnus	0	8
Ash	Fraxinus excelsior	8-12	8-12
Holly	Ilex aquifolium	40	24
Crab apple	Malus sylvestris	0	14
Wild cherry	Prunus avium	2	18
Bird cherry	Prunus padus	2-4	18
Blackthorn	Prunus spinosa	2	18
Sessile oak	Quercus petraea	0	0
Pedunculate oak	Quercus robur	0	0
Purging buckthorn	Rhamnus cathartica	0	2-4
Elder	Sambucus nigra	10	12
Whitebeam	Sorbus aria	2	14-16
Rowan	Sorbus aucuparia	2	14-16
Gorse	Ulex europaeus	0	0
Wych elm	Ulmus glabra	0	0
Guelder rose	Viburnum opulus	8-12	8-12

‘Stratification’ method (warm and/or cold)

Seeds of most species should be mixed with a moisture retentive and aerated medium in a 50:50 ratio of seeds and mixture by volume. The ideal mixture is 50% coarse, sieved peat-alternative and 50% coarse sand.

The mixture should be moist but not waterlogged. Water is added to the dry ingredients, thoroughly mixed and tested by squeezing a handful. When only one drop of liquid can be squeezed out between the fingers then the mixture is ready. This ensures that the seeds remain moist throughout the treatment period, but the exchange of gases (oxygen and carbon dioxide) is not inhibited.

The seeds and/or mixture are placed in a suitable container. Ordinary plant pots (with a layer of sand above and below the seed/compost mixture) are fine.

Seeds of alder and birch can be stratified ‘naked’ (i.e. without the medium). The seeds are placed in cotton bags and soaked in cold water for 48 hours. After a superficial drying, they are placed in polythene bags, which are loosely tied and placed into the fridge for four to eight weeks.

Hot-water treatment

For broom and gorse seeds, a slightly different approach is needed. The procedure is not complicated, but a little unusual.

The seeds will have been collected and stored dry. Just before sowing, the seeds are placed in a heatproof container and two or three times their volume of boiling water is carefully poured over them.

They are left in the cooling water for another 24 hours. They are then ready for sowing.

Non-dormant seeds (requiring no treatment)

Both of our oak species fall into this category. The main problem with these seeds is not how to break their dormancy, but how to stop them from germinating before you want them to!

The best thing to do with these seeds is to sow them as soon as possible after collection (preferably immediately) and then to let nature take its course.

Willows provide an extremely rich habitat for insects, especially moths.

Moth caterpillars feed on the willow leaves. Some feed on only goat willow, others on willows in general. Some feed on plants from the same family, like aspen or poplar.

At least 14 moths that feed on willows are fairly common in Northern Ireland, like the Eyed Hawk-Moth (Smerinthus ocellata), Poplar Hawk Moth (Laothoe populi), Puss Moth (Cerura vinula) and Willow Beauty (Peribatodes rhomboidaria).

One, which is widespread but very difficult to spot as it is very elusive, is the Lunar Hornet Moth (Sesia bembeciformis), which looks very like a hornet!

Leaves

The leaves are oval, up to 12cm long. They are broader than the leaves of other willows (between 1.5 and 2 times as long as broad). They are a dull, dark-grey green on top and woolly below.

The leaf margin is wavy and bluntly toothed. The shortly pointed leaf tip is often curled and there are prominent veins on the underside. At the base of the leafstalks are a pair of small, ear-shaped ‘stipules’, which soon fall off.

Flowers

The flowers are arranged in catkins 2-3 cm long. They appear before the leaves on separate male and female trees in March or April.

Unlike the catkins of birch or alder, they do not hang downwards but are upright. Male catkins are oval, grey and furry at first, turning golden yellow later. Female catkins are longer, a silvery green and more slender.

Many catkin-bearing trees are wind-pollinated. Willows use both the wind and insects – being one of the first sources of pollen and nectar in the spring.

Fruits

Female catkins turn into the fruits, which are silver-green at first, then woolly.

Hair on the seeds helps dispersion by the wind. They are produced in huge numbers and have the potential to travel large distances, but only fresh seed will germinate in moist soil, which somewhat limits their distribution. Seeds are ripe in May-June.

Bark

The bark of goat willow is smooth and grey. Older trees have cracked bark at the base and brittle branches (which makes them less suitable for basketry).

Bark on young twigs is red-brown and shiny. The buds are oval and broader compared to other willows. They are yellow with pointed reddish tips. The wood is very soft, the sapwood yellowish-white and the heartwood brown. The timber is not valued much.

Habitat

Goat willow is a deciduous shrub or small tree, usually 6-15m tall. It is branched from the bottom with a rounded crown.

It grows on wet, neutral and lime-rich soils, though it can grow on drier soils than other willows. It can even form part of the understorey in oak woodlands, though it usually prefers open spaces. It won’t tolerate very dry soil.

Aspen is a pioneer species like birch and willow. This means that it is one of the first plants to colonise new open space.

By doing this, it prepares the ground for other plants which need better soil conditions.

Aspen grows quickly, but its life is short. It may reach 100 years old, which is a short life for a tree. Other trees will later take its place, like oak.

Leaves

The leaves are rounded and similar in shape to a heart. They are between 5 and 8cm long with rounded teeth around the edge.

The leaf is dark green above and below it is a blueish or greyish- green. The stalks of the leaves are flattened and about the same length as the leaves. Each little gust of wind can move the foliage and it may appear that the leaves, or in fact the whole tree, is trembling.

Flowers

In March and April, the flowers appear before the new shoots.

Aspen has only female or male flowers on each tree. The male flowers are brown catkins up to 12 cm long. They turn yellow with pollen.

The female catkins are green and shorter than the male flowers. Female catkins develop into fruits after pollination by the wind.

Fruits

Fruits appear in late May and early June. They are tiny green capsules, which are carried on the wind by white cotton hairs.

Bark

The bark of aspen is greenish-grey and smooth. When the tree is older the bark darkens. It has lenticels (holes through which to ‘breathe’) and is occasionally sticky.

Habitat

Aspen is a pioneer plant. It is normally a modest tree, but it grows very well on moist, rich soil. It needs a place with plenty of light to grow well.

Aspen seeds are dispersed by wind and the seeds can travel a long way from the mother tree. When they reach open ground with good moisture it will grow quickly.

Now the real fun begins – getting out into the countryside and collecting the seeds that we’ll grow into our new trees!

Please remember to obtain permission from the landowner before you begin collecting. A site with special protection, for example, a Site of Special Scientific Interest (SSSI), also requires government permission.

When to collect

It is important to collect seeds at the right time.

If collected too early, the seeds may not be fully developed and you may affect the ability of the seed to germinate.

If you wait too long, the seeds might be taken by the wind or the local wildlife.

Wild cherries will be quickly eaten by birds or wasps. Hazelnuts are easily discovered by mice and squirrels. Acorns might be carried away and buried by jays for eating throughout the winter. Even gorse seed can be eaten by tiny weevils if the pods are left too long on the plant!

Seeds that are dispersed by wind, like birch, can be blown away in even very light winds.

It is a good idea to regularly check the development of fruits that you plan to collect. This helps to determine the best time for collection.

Methods of collection

If the crop is within easy reach, some seeds can be collected by hand from the tree.

With certain types of seed, a large amount of seed can be collected in a short time this way.

Bunches of berries can be carefully removed using secateurs. But please take care not to remove any buds. This is where next years growth will begin.

A stick with a hook can be used to bend branches within reach – but not too far or the branch might break! Or let gravity do the hard work and collect from the ground! This type of collection is especially suitable for larger fruits, such as acorns, hazelnuts or crab apples.

Again, timing is crucial, especially for hazelnuts. The first nuts to fall are often empty and mice will clear up any full ones very quickly!

Short-term storage

Buckets or bags should be used for seed collecting.

One point to remember when collecting is the relatively high moisture content of tree fruits and seeds. If they are kept in sealed or non-breathable containers for any length of time, they will begin to heat up and deteriorate rapidly.

For this reason, fruits should not be piled too deeply (i.e. don’t overfill your buckets) or store them in hessian, cotton or paper bags for the journey home.

They should then be kept in a cool, dry place (a fridge is ideal) until you are ready to extract the seeds.

What’s next?

Depending on the type of fruit you’ve collected, you may need to extract the seed from whatever it’s enclosed in. There are a number of reasons for doing this, but the process for each species is relatively simple.