Flora of Scotland
The flora of Scotland is an assemblage of native plant species including over 1,600 vascular plants, more than 1,500 lichens and nearly 1,000 bryophytes. The total number of vascular species is low by world standards but lichens and bryophytes are abundant and the latter form a population of global importance. Various populations of rare fern exist, although the impact of 19th-century collectors threatened the existence of several species. The flora is generally typical of the north-west European part of the Palearctic realm and prominent features of the Scottish flora include boreal Caledonian forest, heather moorland and coastal machair. In addition to the native species of vascular plants there are numerous non-native introductions, now believed to make up some 43% of the species in the country.
There are a variety of important tree species and specimens; in particular, the Fortingall Yew may be the oldest tree in Europe. The Arran whitebeams, Shetland mouse-ear and Scottish primrose are endemic flowering plants and there are a variety of endemic mosses and lichens. Conservation of the natural environment is well developed and various organisations play an important role in the stewardship of the country's flora. Numerous references to the country's flora appear in folklore, song and poetry.
Habitats
enjoys a diversity of temperate ecologies, incorporating both deciduous and coniferous woodlands, and moorland, montane, estuarine, freshwater, oceanic, and tundra landscapes. Approximately 19% of Scotland is wooded, 14.5% of which is non-native forestry plantation, but prior to human clearing there were much larger areas of boreal Caledonian and broad-leaved forest. Although reduced significantly, significant remnants of the native Scots Pine woodlands can be found in places. Some 21 to 31% of Scotland is covered by heather moorland, while over 20% of Scotland is covered by peatland. Caithness and Sutherland have some of the largest and most intact areas of blanket bog in the world, supporting a distinctive wildlife community. 75% of Scotland's land is classed as agricultural with urban areas accounting for around 3% of the total. The number of islands with terrestrial vegetation is nearly 800, about 600 of them lying off the west coast. Scotland has more than 90% of the volume and 70% of the total surface area of fresh water in the United Kingdom. There are more than 30,000 freshwater lochs and 6,600 river systems.Below the tree line there are several zones of climax forest. Birch dominates to the west and north, Scots pine with birch and oak in the eastern Highlands and oak with birch in the Central Lowlands and Borders. The Scottish coastline includes machair, a fertile grassy duneland formed as the land rose after the last ice age. Machairs have received considerable ecological and conservational attention.
Flowering plants and shrubs
The total number of vascular species is low by world standards, partly due to the effects of Pleistocene glaciations and the subsequent creation of the North Sea. Nonetheless, there are a variety of important species and assemblages. Heather moor containing ling, bell heather, cross-leaved heath, bog myrtle and fescues is generally abundant and contains various smaller flowering species such as cloudberry and alpine ladies-mantle. Cliffs and mountains host a diversity of arctic and alpine plants including alpine pearlwort, mossy cyphel, mountain avens and fir clubmoss. On the Hebridean islands of the west coast, there are Plantago pastures, which grow well in locations exposed to sea spray and include red fescue, sea plantain and sea pink. The machair landscapes include rare species such as Irish lady's tresses, yellow rattle and numerous orchids along with more common species such as marram grass and meadow buttercup, ragwort, bird's-foot trefoil and ribwort plantain. Scots lovage first recorded in 1684 by Robert Sibbald, and the oyster plant are uncommon plants of the coasts.Aquatic species
and water lobelia are common plants of moorland pools and lochans. The least, yellow and white water-lilies are also widespread. Pipewort has generated some botanical controversy regarding its discovery, classification and distribution. It was found growing on Skye in the 18th century, although there was subsequent confusion as to both the discoverer and the correct scientific name – now agreed to be Eriocaulon aquaticum. The European range of this plant is confined to Scotland and western Ireland and it is one of only a small number of species which is common in North America, but very restricted in Europe. There are a few localised examples of the rigid hornwort.Grasses and sedges
Grasses and sedges are common everywhere except dune systems and stony mountain tops and plateaux. The total number of species is large; 84 have been recorded on the verges of a single road in West Lothian.Smooth meadow-grass and rough meadow-grass are widespread in damp lowland conditions, wood sedge in woodlands, and oval sedge and early hair-grass on upland moors. In damp conditions Phragmites reeds and several species of Juncus are found abundantly including jointed rush, soft rush and toad rush, and less commonly the introduced species slender rush. Common cottongrass is a familiar site on marshy land, but saltmarsh sedge was only discovered for the first time in 2004 at the head of Loch Duich.
Endemic species
is an endemic plant found in Shetland. It was first recorded in 1837 by Shetland botanist Thomas Edmondston. Although reported from two other sites in the 19th century, it currently grows only on two serpentine hills on the island of Unst. The Scottish primrose, is endemic to the north coast including Caithness and Orkney. It is closely related to the Arctic species Primula stricta and Primula scandinavica.Endemic species of the Hieracium, Rubus and Taraxacum apomictic complexes occur in Scotland, such as the St Kilda dandelion, endemic to the island of Hirta, identified in 2012, the orange-flowered hawkweed, endemic to Strathnaver, the Shetland Hawkweed, endemic to the Shetland Islands, and Rubus longiflorus, endemic to coastal Angus and Kincardine.
Rare species
Some of Scotland's flowering plants have extremely restricted ranges in the country. These include Diapensia lapponica, found only on the slopes of Sgurr an Utha, Argyll and Mountain bearberry, recorded at only a few mainland locations, and on Skye and Orkney. The pinewoods of Strathspey contain rare species such as creeping lady's tresses, twinflower and the one-flowered wintergreen. Plans to protect the Intermediate wintergreen, also found here, were introduced in 2008. Other nationally rare species include tufted saxifrage, alpine catchfly, sword-leaved helleborine, norwegian sandwort, dark-red helleborine, Iceland purslane, small cow-wheat and yellow oxytropis. Young's helleborine is a rare endemic orchid principally found on bings created by the coal-mining industry in the Central Lowlands and classified as endangered.Invasive plants
Some non-native, invasive species have been identified as a threat to native biodiversity; Giant hogweed, Japanese knotweed, Himalayan balsam and Rhododendron ponticum are generally regarded as the 'big 4'. In May 2008 it was announced that psyllid lice from Japan, which feed on the knotweed, may be introduced to the UK to bring the plant under control. This would be the first time that an alien species has been used in Britain in this way. Scientists at the Commonwealth Agricultural Bureaux International did not believe the lice would cause any environmental damage. Over-grazing caused by the large numbers of red deer and sheep has also resulted in the impoverishment of moorland and upland habitats and a loss of native woodland. In 2012, the Scottish Government published a "Code of Practice on Non-Native Species" to help people understand their responsibilities and provide guidance as to which public body has responsibility for the various habitats involved.Naturalised plants
Among naturalised plants within the British Isles, some, such as Magellan ragwort and pig fern are restricted to Scotland.Deciduous trees
Only 31 species of deciduous tree and shrub are native to Scotland, including 10 willows, four whitebeams and three birch and cherry species.The Meikleour beech hedges located in Perth and Kinross were planted in the autumn of 1745 by Jean Mercer and her husband, Robert Murray Nairne. This European beech hedge, which is in length, reaches in height and is noted in the Guinness World Records as the tallest and longest hedge on Earth.
The Arran whitebeams are species unique to the Isle of Arran. The Arran whitebeam and the cut-leaved whitebeam are amongst the most endangered tree species in the world if rarity is measured by numbers alone. Only 236 S. pseudofennica and 283 S. arranensis were recorded as mature trees in 1980. The trees developed in a highly complex fashion involving the rock whitebeam, which is found on nearby Holy Isle but not Arran, interbreeding with the rowan to produce the new species. In 2007 it was announced that two specimens of a third new hybrid, the Catacol whitebeam had been discovered by researchers on Arran. This tree is a cross between the native rowan and S. pseudofennica.
Shakespeare makes reference to Birnam Wood being used as camouflage for Malcolm Canmore's army before the battle at Dunsinane with MacBeth. There is an ancient tree, the Birnam Oak, standing a few hundred metres from the centre of Birnam. It may well have been part of Birnam Wood at the time of the battle 900 years ago, and remains part of the legend.
Research into the possible commercial use of sea buckthorn was undertaken by Moray College commencing in 2006. The orange berries can be processed into jams, liquors and ointments and the hardy species grows well even on exposed west coasts.