The Shamrock was built in 1899 as a Tamar sailing barge, named after an Irish entry to the Americas Cup Race in that year. After a long working life she ended up being used as a scrap iron store in Plymouth. She was rescued in 1973 and taken to Cotehele where she was restored over 6 years. She is now the largest Tamar barge still fully working and occasionally makes trips up and down the river.
By Victorian times, the parish of Calstock had more lime kilns than any other in Cornwall, with many of these along the river at Lower Kelly and Cotehele where coal and limestone were landed. Often culm (a local soft, peaty coal) was used as the fuel. The coal and limestone was loaded into the top of the kilns and was allowed to burn for a week; this produced quicklime which was raked out of the bottom. The lime from the kilns was transported by horse and cart to the nearby farms and market gardens.
Cotehele House belonged to the Edgcumbe family for nearly 600 years before being donated to the National Trust in 1947, together with over 1000 acres of land. The house is largely Tudor, and by the 1750s it was already attracting tourists seeking to visit a historic building.
Cotehele house includes a turret clock which is powered using weights on a rope wrapped around a capstan, rather than a pendulum. The clock has no face and instead strikes a bell on the hour. It is the earliest turret clock in its original position and still working, and possibly the earliest working turret clock in the world. The design was relatively common in the 14th Century but most were replaced and scrapped.
The gardens at Cotehele were constructed during Victorian times and are now Grade II* listed in the Register of Parks and Gardens of Special Historical Interest. The formal Italian terraced gardens around the house are connected by a tunnel to the Valley Garden, which is planted with trees including rhododendrons and azaleas which produce profuse amounts of brightly-coloured flowers in spring. Within the Valley garden is a Victorian Summerhouse and former mediaeval elements including an exceptionally well-preserved dovecote and a pond which was originally used to farm carp to supply fish for the kitchens.
Bluebells are very vulnerable to trampling. The reason for this is that when their leaves emerge in the early part of the year, they are powered by the stored sugars in their bulbs. Sunlight is very limited at this time of the year and even more so in the shady places where they grow. In order to survive, they then need to photosynthesise flat-out to store enough starch in the bulb for next year's growth. If a bluebell’s leaves are crushed, it cannot photosynthesise and and doesn't have enough reserves left in its bulb to grow new ones. It's therefore important to stick to footpaths in bluebell woodland and best to take photos with a zoom lens from there as wandering around in the bluebells to take photos will inadvertently kill them.
Generations of plants and algae alternate between two different kinds of life form. One generation produces spores and these grow through cell division into a new organism. This then produces eggs and sperm which combine to grow into the first kind of organism again.
In the case of flowering plants, the organism that produces the eggs and sperm is only a tiny beast consisting of a few cells that is contained entirely within its parent. In mosses, it's the other way round: the organism that produces the eggs and sperm is the main one and the spore-producer is a smaller plant, reliant on its parent. In the case of algae, both are independent organisms in their own right.
The evolutionary advantage is that the overhead of sexual reproduction can be deferred for a generation, so the spore-bearing generation can be optimised to produce loads of clones cheaply with the safety net that next time around the genes will get a mix-up. That gene mix up from the sexual reproduction phase provides insurance in case something in the environment changes or there is some dodgy genetic copying that would scupper ongoing generations of clones.
The mines in the valley at Danescombe extracted tin, copper and arsenic. The ore was transported down the tramway which is now the track along the valley and was loaded into boats at Lower Kelly Quay.
During the 9th Century, the Danes are thought to have landed in the Tamar Estuary; the Cornish allied with the Danes to fight against the Saxons who were at the time pushing into East Cornwall. It is said that Danescombe takes its name from the Danes landing and settling in the valley. At one time this was celebrated in Calstock with locals dressed as Vikings rowing up the river to Danescombe.
Just before the path ends in a junction, it passes some iron railings. This is a well and is recorded in the first Ordnance Survey map from the 1880s.
The early purple orchid gets its common name from its spring flowering time - it appears at a similar time to bluebells although it lasts a bit longer. It has a Latin name meaning "virile" which is in keeping with the word "orchid" coming from the Greek word for testicle (on account of the shape of the tuber).
The rate at which a tree grows varies through the year depending on the amount of light and moisture available. This is visible in a sawn tree trunk as a ring where the wider lighter area wood is laid down more quickly in spring-early summer and then the narrow darker area more slowly in late summer-autumn. Each ring corresponds to a year and so the age of the tree can be worked out by counting the rings.
Kingfishers are found near slow-moving or still water where they dive to catch fish, as their name implies, but they also eat many aquatic insects, ranging from dragonfly nymphs to water beetles.
The Kingfisher is able to switch between light receptors in the main central area of its eye and a forward-facing set when it enters water, allowing it to judge distances accurately underwater. It is estimated that a female needs to eat over twice her own body weight in order to increase her condition sufficiently for egg laying.
The unmistakable metallic blue and orange birds fly fast and low over the surface of the water so may only be apparent as a blue flash. The pigment in their feathers is actually brown but the microstructure of their features results in light interference patterns which generate the brilliant iridescent blue and orange colours. Unfortunately the result, during Victorian times, was that kingfishers were extensively killed for display in glass cases and for use in hat making. The population has since recovered and is now limited by the availability of suitable waterways.
Chestnut trees grow over the path and green spiny husks containing the nuts can seen in October.
Since chestnuts don't need to hang around for a long time on the ground, they are nutritionally more similar to a cereal - containing principally starch and sugars - than a typical nut. They contain very little fat and are consequently much less calorific than other nuts: the kernels contain around a third of the calories of a similar weight of other nuts.
In 1483, Sir Richard Edgcumbe joined a rebellion against King Richard III. The rebellion failed and Edgcumbe was pursued by the King's troops into the woods at Cotehele. Edgcumbe managed to escape by throwing his hat into the river, giving the impression he had drowned, and lived in exile in Brittany until Henry Tudor took the throne. On his return, Edgcumbe built the chapel in the spot where he had thrown his hat into the river to give thanks for his escape.
The Tamar Valley Area of Outstanding Natural Beauty has a similar conservation status to a National Park. It encompasses an area of 75 square miles around the rivers Tamar, Tavy and Lynher, partly in Cornwall and partly in Devon. This also includes an area of Cornwall and West Devon mining landscape World Heritage Site, 41 county wildlife sites and over 1700 hectares of woodland. It was first suggested in 1963 that the Tamar valley area should be designated but this was only eventually granted in 1995.
The name Tamar is documented in the second century and likely to be substantially older. It is thought it might share a common origin with the River Thames and both might stem from an ancient Celtic word meaning "dark". The source of the river is within 4 miles of the North Cornish Coast and the river flows 61 miles south across the peninsula forming the majority of the historic border with Devon. Work is being done by the Environment Agency to improve the water quality of the Tamar and its tributaries by reducing the amount of run-off of phosphate fertilisers into the rivers.
Danescombe Sawmill was opened in 1878 and used a 43 foot waterwheel to drive the sawing machinery. Power from the waterwheel was also used to haul carts up the tramway, which is now the track. These were loaded with timber grown on Cotehele Estate land that was landed on the quay at the bottom of the track. Using just the power from the waterwheel, the mill could saw 2000ft of timber in an hour. Even the sharpening of the saw was mechanised using water power. Despite its efficiency, the mill was relatively short-lived; by 1905 it was disused and had lost its iron roof, which was presumably sold as scrap. Its demise is thought to have been brought about by the closure of the nearby mines as much of the sawn timber was used in the mines.
The small holiday cottage where the track up the Danescombe valley opens out by some buildings is an engine house thought to be built in the mid 1830s for a pumping engine. At this point, it was known as Danescombe Mine. However, it's thought that the mine was first worked for copper and arsenic from the 1820s as Wheal Calstock. The larger engine house slightly further up the valley was built in 1881-2 as part of Cotehele Consols but by 1884 the engine was put up for sale. In 1973, this engine house was converted by the Landmark Trust into a holiday cottage.
A quay at Cotehele was first recorded in 1731, located slightly closer to Cotehele Bridge than the main area of the present quay. The quay once served both the Edgcumbe family's Cotehele estate and also the mines in the area. Copper ore and arsenic were exported whilst timber and coal were imported.
Cornwall's iconic engine houses were built to house huge beam engines - a type of steam engine with a pivoting beam. This configuration was particularly suited to powering pumps to stop the quarry pits and mines from flooding as water trickled into them from above. Inside the engine house, steam from a boiler would push up a piston, causing the beam to tilt downwards, pushing the pump down into the shaft. The steam would then be shut off and cold water would be used to condense the steam within the piston back into water, creating a partial vacuum. Atmospheric pressure then pushed the piston back down into the vacuum, raising the beam and lifting water out of the shaft. The valves to apply the steam and cold water were mechanically automated, maintaining a steady rocking motion of the giant beam.
In tidal rivers, the discharge of freshwater and friction with the riverbed effectively "holds back" the rising tide. The further up the tidal region of the river, the shorter the interval between low and high tide and the faster the rising tide comes in when it eventually does.
Compared to many native trees, the beech colonised Great Britain relatively recently, after the last Ice Age around 10,000 years ago. Beech trees have a shallow root system and are therefore often found in areas where water is plentiful such as near rivers. In the 17th and 18th Centuries, tall, stately beech trees were very fashionable in the estates of wealthy landowners and many mature beech woodlands today are the result of 18th Century parkland landscaping projects.
Beech trees can live up to 400 years but the normal range is 150-250 years. Beech trees respond well to pruning and the lifetime of the tree is extended when the tree is pollarded. This was once a common practice and involves cutting all the stems back to a height of about 6ft during the winter when the tree is dormant. The 6ft starting point kept the fresh new growth out of the range of grazing animals. When allowed to grow to full size, a beech tree can reach 80ft tall with a trunk diameter of around 3ft.
The word "beech" is thought to have the same origins as "book" as beech (most probably the bark) was used as a writing material in which to carve runes by Germanic societies before the development of paper. This is still apparent in modern German where the word for "book" is buch and "beech tree" is buche.
The fruit of the beech tree is known as "mast" or, less cryptically, "beechnuts" and these are not produced until the tree is 40-60 years old. The small triangular nuts are encased in spiky husks which split and drop from the trees from late August to early October. The kernels of these are edible and are similar to hazelnuts. They were once used as a source of flour, which was ground after the tannins had been leached out by soaking them in water. If you find them too bitter, you might want to try this trick, although toasting them in a hot pan is also a good option.
Young beech leaves can be used as a salad vegetable, which are described as being similar to a mild cabbage, though much softer in texture. Older leaves are a bit chewy, as you'd expect.
Beech bark is very delicate and does not heal easily. Consequently some graffiti carved in beech trees is still present from more than a century ago. This is a practice that should be strongly discouraged as it permanently weakens the tree, making attack by insects more likely which can prematurely end its life.
Beechwood ageing is used in the production of Budweiser beer but beech is not the source of flavour. In fact beechwood has a fairly neutral flavour and in the brewing process it is pretreated with baking soda to remove even this. The relatively inert strips of wood are then added to the fermentation vessel where they increase the surface area available for yeast. It is the contact with yeast that produces the flavour in the beer, not the beech itself.
Beechnuts can be used very effectively as a thrifty alternative to pine kernels to make pesto. Collect one trouser pocketful of beechnuts. Shell them over a large cup of tea with a friend, toast the kernels over a medium heat in a dry pan, then grind with a pestle and mortar (surprisingly easy once toasted). Chop 4 sprigs of basil each about the size of your hand - roughly half a supermarket pack. Add to this a finely chopped small clove of garlic and a good pinch of salt and freshly ground black pepper. Then shave (with a peeler) or grate a lump about the size of the end of your thumb of some hard salty cheese such as Pecorino or Parmesan (a supermarket basic range imitation will do fine). Finally add a good slug of extra virgin olive oil and it's time to say "proper job". It makes a ramekin full which doesn't seem a lot but it is so packed with flavour that it goes a surprisingly long way.
For such a widespread tree, the oak is surprisingly inefficient at reproducing naturally. It can take 50 years before the tree has its first crop of acorns and even then, the overwhelming majority of the acorns that it drops are eaten by animals or simply rot on the ground. Squirrels play an important part by burying acorns and occasionally forgetting a few which have a much better chance of growing than on the surface.
The older an oak tree becomes, the more acorns it produces. A 70-80 year old tree can produce thousands. Acorns are high in carbohydrates and as well as being a staple food for squirrels, they are also a really important food for deer and make up a quarter of their diet in the autumn.
Tannins are natural preservatives. The reason why red wine keeps much longer than white is that the grape skins that give the red colour also contain tannins. Oak leaves, wood and acorns all contain a high level of tannins. When wine is aged in oak, the wooden barrels release more preservative tannins into their contents.
The (leather) "tanning" process got its name as it involved extracting the tannins from acorns or oak bark and soaking these into animal hides over 1-2 years to preserve them. From the brown oak juice containing the tannins, the colour "tan" was named and from this the expression "sun tan" arose.
The high levels of tannins in oak make large amounts of oak leaves or acorns poisonous to cattle, horses, sheep, and even goats, but not to pigs as they were domesticated from wild boar which were adapted to foraging in the oak forests, like deer. Acorns were also eaten by people in times of famine. The acorns were soaked in water first to leech out the bitter tannins and could then be made into flour.
Wood from the oak has a lower density than water (so it floats) but has a great strength and hardness, and is very resistant to insect and fungal attack because of its high tannin content. This made it perfect for shipbuilding.
Oak was often associated with the gods of thunder as it was often split by lightning, probably because an oak is often the tallest tree in the area. Oak was also the sacred wood burnt by the druids for their mid-summer sacrifice.
Bracket fungi can be recognised by tough, woody shelf-like growths known as conks. Some species can live for a very long time and are often coloured with annual growth rings.
Bracket fungi are one of the most important groups of fungi responsible for wood decay. This is good for nutrient cycling but less good if you own a forestry plantation. Many bracket fungi begin on living trees and can eventually kill a branch or whole tree by damaging the heartwood and allowing rot to set in. They can continue to live on the dead wood afterwards and a much more diverse range of species of bracket fungi are found in old natural forests with lots of dead wood.
The red campion produces a blaze of pink flowers along hedgerows in the spring with the most intense flowering period occurring between late April and the end of June. A scattering of flowers continue throughout the rest of the summer. In the mild Cornish climate, a few plants can often be seen flowering during winter months.
Despite being called red campion, its flowers are most definitely pink - varying quite widely in shade from vibrant deep pinks to very pale. The colour is produced by red anthrocyanin compounds which are also responsible for red autumn leaves and red tinges on new growth in some plants as well as flower colours. In red campion, the intensity of the colour is controlled by a pair of genes and several other genes control the exact balance of anthrocyanin compounds within the petals. These are passed down the generations and so pale pink parents are likely to produce pale pink offspring.
The second part of the Latin name of red campion - dioica ("two houses") - refers to the plants' gender. Some plants are male and others are female. The male plants' flowers can be recognised from five yellow stamens sticking out from a protruding ring in the centre of the petals. The female plants' flowers have no protruding ring and instead have 5 curly white stigmas. These produce a white froth to trap pollen.
Red campion is also known as "red catchfly". The flowers are an important nectar source for larger pollinating insects including butterflies, bees and hoverflies. Much smaller flies drawn to the nectar can become stuck in the froth on the stigmas of the female flowers but this is not intentional by the plant (it doesn't eat them).
Red Campion seeds ripen between June and August. The seed capsule has teeth at the end which fold back when the seeds are ripe, allowing them to escape when it is shaken by the wind (known in botanical circles as "the pepper pot mechanism"). Each seed weighs only one thousandth of a gram, allowing it to be carried as far as possible by the wind. Nevertheless many end up falling quite close to the parent which is why red campion often occurs as a cluster of plants.
The genus name for campions - Silene from the often-drunk Greek woodland god Silenus whose name derives from the Greek word for saliva. The name is thought to be based on the froth on the female flowers used to trap pollen although its habitat preference including semi-shade within woodland also fits fairly well.
Red campion is also known by a few local names including Johnny Woods (from its habitat) and Ragged Jack (from its flower shape). Some are colour references such as Scalded Apples, and particularly in the southwest, Red Riding Hood. Cuckoo-flower is a reference to the time of year that it flowers. Another name - "Batchelors' buttons" - suggests it was once worn as a buttonhole by young men.
The roots of red campion contain saponins (soapy compounds) which protect the plants against microbes and fungi. These compounds make it easier for large molecules such as proteins to enter cell membranes. This has the potential to increase the effectiveness of immunotherapy against cancer by allowing immunotoxins to enter the cancer cells more easily.
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