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Trees

Trees are the foundation plantings of public parks, gardens, cemeteries and avenues across the world while at the same time being the most prominent plants in any garden. Their size and form makes them imposing features of the landscape so designers can take advantage of stunning foliage colours whether permanent or seasonal, natural or man-made.

Global context

Woody trees are key components of rich and biologically diverse ecosystems that influence both weather and climate representing a vast carbon sink: they are also the source of food, timber, medicines and other products useful to humans.

In 2017 Botanic Gardens Conservation International (BGCI) introduced GlobalTreeSearch, an authoritative global inventory of tree species and their distributions.[1] The number of tree species currently known to science is 60,065 which comprises about 20% of all angiosperm and gymnosperm (flowering plants and conifers) species. About 45% of these species occur in just 10 plant families, the most species rich being the Leguminosae, Rubiaceae, and Myrtaceae with the most country-endemic species occurring in Brazil, Australia, and China, and islands where isolation has encouraged speciation as in Madagascar, Papua New Guinea, and Indonesia. Genera with most numerous species were Syzygium (1069), Eugenia (884), Eucalyptus (747), all in the family Myrtaceae, and followed by Ficus (Moraceae), Diospyros (Ebenaceae), Psychotria (Rubiaceae). Brazil has 8715 tree species, Colombia 5776, and Indonesia 5142. The countries with he most endemic tree species are Brazil (4333), Madagascar (2991), Australia (2584), and China (2149). Tropical biomes have the most species with the greatest number occurring in the Neotropic biome (over 23,000).About 58% of all tree species are single-country endemics. GlobalTreeSearch aims to assess the conservation status of all the world’s tree species by 2020.

For the purposes of the survey BGCIs Global Tree Specialist Group defines a tree as: A woody plant with usually a single stem growing to a height of at least two metres, or if multi-stemmed, then at least one vertical stem five centimeters in diameter at breast height.

The native and introduced trees of Britain are of special significance because it was mostly from this stock that the introductions to the Neo-Europes, the countries of the former British empire, were drawn. The cultural and horticultural influences of Europe, and especially Britain, were felt most strongly in North America, Canada, Australia, and New Zealand but also in many other countries of the Commonwealth and, by diffusion, many other parts of the world. Britain acted as a plant hub or entrepot in an unprecedented phase of Cultivated plant globalization driven by British science and their love of gardens and gardening.

For this international reason alone it is worthwhile tracing the historical path of tree introduction to the British Isles.

According to the Scientific American (2015) the world today contains over three trillion individual trees equating to about 400 trees for each human (in 2019). The total is about half the number present in 12,000 BP and about half grow in tropical and subtropical forests.

Europe

America

The most comprehensive account of the trees of North America (excluding Mexico) is the 14-volume Silva of Charles Sargent which occupied him for 20 years from 1891 to 1902; it lists 585 different kinds. Other historical accounts are listed in the references.

Prehistory

Iron Age man possibly introduced Ulmus carpinifolia.

 

Romans

Romans are credited with the introduction to Britain of the Sweet Chestnut Castanea sativa, Walnut Juglans regia,

Early records

The first publication of the newly-formed Royal Society in 1662 was a response to the need for ship timber at the time of the Restoration (1660). Written by Fellow of the society and wealthy diarist John Evelyn (1640-1706) this was the first book published by the society in 1664. Sylva was an account of the trees being grown in Britain at that time mostly for use as shipbuilding timber for the British navy. About 50 pages were devoted to oaks, the main source of shipbuilding timber. Included were not just native trees but those introduced to the island for their economic as well as ornamental interest. Evelyn regarded the books as being: ‘not altogether … for the sake of ordinary rusticks, meer foresters and woodmen, but for the benefit and diversion of Gentlemen and persons of quality.’ He successfully found and audience of estate owners and gentlemen who were keen horticultural and botanical collectors of plant novelties.

The British Isles are not endowed with large numbers of native trees. Today the number of native trees (post-glacial trees present for about 8000 years) is towards 40 species (there are around 15 large shrub species and 24 naturalized tees of which 14 are from Europe, 9 from North America, and 1 from Asia). , and only apomictic (asexually reproducing) whitebeams, Sorbus, are considered endemic (found only in this region). Evelyn no doubt stimulated the further introduction of trees which today number several thousand species of which ? are naturalized (have spread further to persist without human assistance). Evelyn’s Sylva lists the introduced species of the 16th and 17th centuries in order of arrival:

 

16th century

Acer pseudoplatanus, Sycamore, from Montane C and S Europe grown in Scotland in possibly 15th century but certainly 16th becoming widely naturalized.
Picea abies, Norway Spruce, N Europe recorded in 1548.
Platanus orientalis, Oriental Plane, also introduced around 1548.
Pinus pinea the Stone Pine from Italy probably dates from about 1548
Abies alba, Silver Fir, from C and S Europe also introduced at this time but now decimated by gall-forming aphids.
Quercus ilex, Holm Oak, from Mediterranean introduced in around 1580.
Pinus pinaster from the coastal Mediterranean was probably in Britain by 1596.
Thuja occidentalis, Arbor-vitae from Eastern North America was introduced in 1597 (to be followed later by many other trees from this region). This is the first record of a tree brought from eastern North America.
Larix europaea, Larch, arrived in 1629.
Robinia pseudoacacia, from North America was introduced from the Jardin des Plantes around this time.

 

17th century

Aesculus hippocastanum, native to Albania and Greece, probably received by John Tradescant of Lambeth from the Jardin des Plants in turn from Constantinople as a tree grown by the Turks and well established in his garden in 1633.
Cedrus libani from the Middle East introduced in about 1640
Pinus sylvestris had moved down from Scotland by about 1650 while other introduced trees included, White Poplar, Populus alba, from Europe, the European Lime, Tilia europaea was being imported from Holland to form famed avenues at the time of the Stuarts (1371-1707). Taxodium distichum from SE North America.
Liriodendron tulipiferum from Eastern America introduced by 1658.

After Evelyn:
Acer platanoides, Norway Maple, now widely naturalized, introduced to the Edinburgh Botanic Gardens in 1683
Juglans nigra in 1686.
Sorbus intermedia, Swedish Whitebeam from Scandinavia was introduced in 1690

 

18th century

Formal geometric landscapes like those of La Notre (1613-1700) at Versailles were replaced by the more informal English landscape garden of curves and lakes introduced by Kent, Brown and Repton. There was at the end of the century the widespread planting of oak for ship’s timber

Pinus strobus, White Pine from eastern North America introduced around 1705.
Catalpa bignonioides, Indian Bean Tree, introduced to London by Mark Catesby from E North America.
Salix babylonica, Weeping Willow, introduced the Euphrates c. 1730 by a Mr Vernon.
Quercus cerris from the Balkans introduced c.1735
Thuja (Platycladus) orientalis used in Victoria cemeteries around 1743.
Ailanthus altissima, Tree of Heaven from China introduced c. 1750 by Pere D’Incarville.
Araucaria araucana, Monkey Puzzle from Chile introduced by Archibald Menzies c. 1795

 

19th century

From about 1775 coke made from coal replaced wood charcoal reducing the demand for wood in the iron and steel industries and by 1866 all import duties on foreign and colonial timbers was removed. As a consequence timber production in the 19th century was no longer profitable. Nevertheless, experimentation with different timbers occurred on private estates and those with promise were planted in woodlands under the eye of either the Royal Scottish Forestry Socity (est. 1854) or the Royal Forestry Society of England, Wakes and Northern Ireland (est. 1882).

David Douglas’s trip to the Pacific coast of North America in 1824. The decades around 1850 are characterized by a fashionable interest in architectural and colourful formal conifers as intrepid adventurers introduced new species from the forests of China and the American West coast. Collectors were sent out by the Horticultural Society and private nurseries like that of Veitch but most arrived through the plant hunting of just a few men, mainly Douglas, Fortune, Jeffrey, Lobb and Veitch.

Japan opened up to trade around1861 and its ornamental trees , many of them earlier introductions from China, found their way to Europe. John Gould Veitch was the first English nurseryman to bring back many plant trophies.

Aesculus x carnea hybrid of East and West first planted in 1818.
Abies grandis, Giant Fir 1825 Douglas.
Pseudotsuga menziesii Douglas Fir 1827 Douglas.
Picea sitchensis Sitka Spruce 1831.

Cedrus deodara was introduced in 1831 but not generally available until the 1840s.
Pinus nigra from Central Europe raised by Edinburgh nurseryman Peter Lawson in 1835.
Cupressus macrocarpa grown from seed (of unknown provenance) provided by Aylmer Labert and grown in the RHS garden at Chiswick.
Pinus radiata Monterey Pine from California was introduced in 1843 grown from seed acquired from the St Petersberg Botanic Gardens collected in the time when Russia had a settlement on the Californian coast.
Sequoia sempervirens from California was introduced in 1843 grown from seed acquired from the St Petersberg Botanic Gardens collected in the time when Russia had a settlement on the Californian coast.
Tilia petiolaris Weeping Silver Lime was also introduced around 1843 from unknown sources.
Cryptomeria japonica was introduced around 1844 being among the many plants introduced from China and Japan by Scotsman Robert Fortune.
Cedrus atlantica Atlas Cedar was introduced from Morocco by Lord Somers around 1850.
Tsuga heterophylla Hemlock was introduced by John Jeffrey sent from Edinburgh to collect in America’s north-west.
Calodedrus decurrens c. 1850 introduced by John Jeffrey sent from Edinburgh to collect in America’s north-west.

Pinus contorta, Lodgepole Pine introduced by John Jeffrey around 1850 but not used in forestry until about 1930.
Araucaria araucana from South American seed grown in bulk numbers in 1843 from collections by William Lobb of Veitch’s nursery.
Sequoiadendron giganteum Giant Redwood from California was also grown in bulk in 1853 by from collections by William Lobb Veitch’s nursery.
Thuja plicata Western Red Cedar also grown in bulk in 1853 by from collections by William Lobb Veitch’s nursery.
Chamaecyparis nootkatensis from Nootka introduced to Britain via a German nursery in 1853.
Chamaecyparis lawsoniana introduced in 1854 from California by William Murray of the nursery firm Lawson when searching for the lost collector John Jeffrey.
Chamaecyparis obtusa Hinoki Cypress introduced by John Veitch in the 1860s.
Chamaecyparis pisifera, Sawara Cypress introduced by John Veitch in the 1860s.
Cupressocyparis leylandii, Leyland Cyprress, appeared around 1888 as natural hybrids between the Nootka and Monterey cypresses growing nearby.
Prunus serrata, Flowering Cherry introduced from Japan in the 1890s by J.H Veitch, mainly the popular ‘Fugenzo’.
Populus trichocarpa, Cottonwood, was introduced in 1892 and found a useful wood for matches.

 

20th century

At the start of the 20th century the attention had turned to Central and Western China, mainly through the work of Irishman Augustine Henry, but in 1899 Ernest Wilson was sent by the firm of Veitch into this remote and region launching an unprecedented era of plant exploration that yielded many of the trees, shrubs and other plants that make up the bulk of the popular exotic flora in Western gardens: apples, cherries, maples, rowans and so on.

Conservation

Launched in 2015, the Queens Commonwealth Canopy (https://queenscommonwealthcanopy.org/ and https://www.royal.uk/what-queens-commonwealth-canopy ) is a unique network of forest conservation initiatives that involves all 53 countries of the Commonwealth.

Feydeau, E. de 2013. From Marie-Antoinette’s Garden. Flammarion: Paris lists an Inventory of seed-bearing trees held in the garden at Versailles at Petit Trianon in 1795. pp. 234-235

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