Types of Tree

Bob Gary's survey records two types of Alder: Alnus glutinosa or Common Alder, and Alnus incana or Grey Alder. Alders are of the Birch family. The photographs below were taken by Aileen Milne on the 8th December 2020 are of a Common Alder.  Initially it was thought that they were of a Smooth Alder, som we asked Bob for help. Bob writes:

The lovely photos are probably of a common alder (Alnus glutinosa), whose male catkins are deep wine red through the winter. Smooth alder is a shrub and its male catkins are yellow in colour. There are all sorts of alder trees - common, grey and Italian are probably the most common. Only the common one is native.

The cones and fruit were a surprise to many of us !

Beech is one of the most recognisable trees with pointed buds, small neat leaves which stay on the tree till later in autumn. They have copious fruit – beech mast that is much loved of squirrels. The thin bark 
is fragile and does not repair well, so graffiti remain for a long time. There are many fine beech trees throughout the park.

I have searched, so far in vain, for a flower of the deep shade and leaf litter under beech trees, the Bird’s-Nest Orchid. This occurs close to Linn Park and I hope to find it here one day. If anyone does please let me know!

In Spring the large sticky buds burst and the large five lobed leaves erupt. These are quickly followed by the pyramidal towers of white and pink flowers. These are a rich source of nectar in the early season for bees. Later the conkers appear in their fleshy spiked casings as the leaves turn golden and are shed for the winter.

Even in the winter the stately form of the tree is revealed. It is the classic tree of parkland or the village green. The Woodland Trust have produced this lovely video of a Horse Chestnut throughout the year [Its on YouTube].

Where it came from.

It is not a native tree being introduced from the Balkans in the seventeenth century. The Turks used it for lame horses so It was called horse chestnut.

More recently the conkers were ground up and used as a flour substitute during the world wars. They contain soap like chemicals and are currently added to proprietary shampoos to enhance their “natural” image. Recently they have been shown to contain aescin which is an effective treatment for sprains and bruises, (as the Turks knew), and there are plans for large plantations to produce this in commercial quantities.

The tree is chiefly grown nowadays for ornamental purposes, in towns and private gardens and in parks, and along streets.

Conkers:

A conker is the seed of the horse chestnut tree (not the sweet chestnut tree where we get edible chestnuts from). It is a hard brown nut which is found in a prickly casing.They are called Buckeyes in the US.

Lastly, what to do with old conkers? - the Victorians used to use them to deter moths.

Medical use
Varicose veins and other circulatory problems (chronic venous insufficiency). Taking horse chestnut seed extract containing 16% to 20% of the chemical aescin can reduce some symptoms of poor blood circulation, such as varicose veins, pain, tiredness, swelling in the legs, itching, and water retention.

Genus
Aesculus can be deciduous trees or large shrubs with showy flowers, palmately-lobed leaves and sometimes good autumn colour. A. hippocastanum is a large, broad-crowned deciduous tree. Leaves large, with 5-7 leaflets, turning red-brown early in autumn. Flowers creamy-white with a yellow spot that turns red with age. Fruit: large, spiny.

There is a lot more information on Wikipedia.

In recent years a bug has invaded Britain, called the Horse chestnut leaf miner - (Cameraria ohridella). The Forestry Commission are aware of it.

There are some 30 places in the park where these trees are to be found. According to Bob Gray's survey there are:

• Lawson's cypress - Lawsoniana
• Sawara cypress - Pisifera
• Squarrosa cypress - Pisifera 'Squarrosa'

In the Sawara cypress (C. pisifera) the cones are tiny and the needles have have spreading tips; in Lawson cypress (C. lawsoniana) the cones are bigger (c. 8 mm) and the scale leaves have scarcely spreading tips.

By Spring 2020, it has become apparent there is an infected tree at reference point 265. The fatal disease is caused by Phytophthora lateralis, a fungal-like pathogen of Lawson cypress mainly. First reported in the UK in 2010 it has been recorded causing infection in Sawara cypress and a couple of other conifers but it almost exclusively affects Lawson cypress. Infected trees have been felled in Dumbarton Cemetery

The wych elm is widespread in Linn Park. The leaves can be very large, up to 18cm. They have an asymmetric base and have a serrated edge and end with a tapered point. The leaves are hard, matt and rough on top and
have a very short stalk onto the twig. Wych Elm flowers early in spring before the leaves appear and is wind pollinated. Elms can produce by both seeds and suckers, but wych elms tend to have fewer suckers and spread mainly by the ovoid fruits (samaras) which can travel far on the wind.

The range and abundance of wych elm across the UK has been reduced in recent decades by the spread of Dutch Elm Disease. This disease was first described in the Netherlands, hence the name, affects all elm
species. This disease struck in the 1960’s and destroyed many characteristic trees of the landscape especially the English Elm. As this rarely spreads by seed, the trees in one area were clones and very susceptible. The disease is due to a fungus that is spread by a bark beetle. There is a limit to how far they can fly and they are attracted to mature trees, so as the trees were affected and were felled the spread was limited. Later some stumps rejuvenated, developed suckers that were disease free which in turn then grew into small trees and again in the 1990’s the disease struck at these new trees.

The wych elm is a native tree and is by far the commonest elm in Scotland. Its Gaelic name of Liobhann is anglicised as Leven, and gives its name to the two Loch Levens (Kinross and near Ballachulish) thereby giving an indication of the tree’s geographic spread. In Scotland it only grows to 25m, there are few large trees in Linn Park but there are many smaller trees.

The wood of an elm is considered too flexible for most timber uses, but it is water resistant and is used for bridge posts and boats.

The term wych refers to the pliant nature of the wood and not witches who are said to shun elms.

This is widespread in the Park and its dramatic leaves and berries make it distinctive. The berries only occur on the female trees and the crop depends on the weather in the previous spring rather than a predictor of the subsequent winter. It is a tree associated with magic and like elder is believed to have power over horses. In the Victorian era it was the favourite wood for horsewhip as the wood is white, light and pliant.

The prickles ‘cost’ the plant to arm its leaves. So small saplings have fearsome prickles to prevent grazing animals having a nibble, however mature trees often have few if any prickles.

There is a wonderful avenue of Lime Trees as you enter Linn Park from Clarkston Road. They are tall and can grow to 45m high. These limes are a hybrid of the two limes native to the UK.

These limes have distinctive heart shaped leaves with asymmetric bases, a fine point and fine tufts of brownish hairs on the underside of leaves where the central vein splits off.

The distinctive fruit has a leaf like structure called a bract. If the fruit is round it is infertile, if it is lemon shaped it is fertile. Seed is usually infertile in the UK as it requires a hot June and then a warm July and August to be fertile and we don’t often have summers like this.

Limes like to sprout from their bases and these suckers can be planted to grow new trees. They are easy and cheap to propagate and so they are widely planted in parks and streets. They grow well and tolerate being chopped back.

The lime itself has a sweet plentiful sap and is loved by insects especially aphids which can secrete the sap as they are process it to get the protein. So parking your car under a lime is a bad idea in early summer as it will be covered by a sticky liquid. This sticky sap also attracts Greater Spotted Woodpeckers. I have seen in other woods, horizontal lines of woodpecker holes round the trunk. It is thought they may then drink the sap or even come back later and “harvest” the insect that are attracted.

The name is nothing to do with the citrus fruit rather it is derived from their old name of Linden.

Yew trees are widespread in the Park. The leaves and seeds are distinctive. The red seeds are actually modified cones called an aril. The flesh is sweet but the hard seeds and leaves are very poisonous. Thrushes and waxwings eat the seeds and they pass through unchanged in their droppings, but other birds such as hawfinches, greenfinches and great tits crush and eat them and are unaffected.

They are remarkable trees, a mature tree has the densest darkest foliage of any evergreen with a buttressed trunk close to the colour of finest mahogany. It's wood reputedly outlasts iron in the soil.

In the middle of Scotland (Fortingall, Perthshire) there are the living fragments of a shell of amazing tree which may be 2,000 to 9,000 years old!. It is in the grounds of a churchyard and this is a common association.