Inosculation is a natural phenomenon in which trunks, branches or roots of two

tree In botany, a tree is a perennial plant with an elongated stem, or trunk, usually supporting branches and leaves. In some usages, the definition of a tree may be narrower, including only woody plants with secondary growth, plants that are ...

s grow together in a manner biologically similar to the artificial process of

grafting Grafting or graftage is a horticultural technique whereby tissues of plants are joined so as to continue their growth together. The upper part of the combined plant is called the scion () while the lower part is called the rootstock. The succ ...

. The term is derived from the Latin roots ''in'' + '' ōsculārī'', "to kiss into/inward/against" or etymologically and more illustratively "to make a small mouth inward/into/against"; trees having undergone the process are referred to in forestry as gemels, from the Latin word meaning "a pair". It is most common for branches of two trees of the same

species In biology, a species is the basic unit of classification and a taxonomic rank of an organism, as well as a unit of biodiversity. A species is often defined as the largest group of organisms in which any two individuals of the appropriat ...

to grow together, though inosculation may be noted across related species. The branches first grow separately in proximity to each other until they touch. At this point, the bark on the touching surfaces is gradually abraded away as the trees move in the wind. Once the

cambium A cambium (plural cambia or cambiums), in plants, is a tissue layer that provides partially undifferentiated cells for plant growth. It is found in the area between xylem and phloem. A cambium can also be defined as a cellular plant tissue from w ...

of two trees touches, they sometimes self-graft and grow together as they expand in diameter. Inosculation customarily results when tree limbs are braided or

pleached Pleaching or plashing is a technique of interweaving living and dead branches through a hedge creating a fence, hedge or lattices. Trees are planted in lines, and the branches are woven together to strengthen and fill any weak spots until the hedg ...

. The term ''inosculation'' is also used in the context of

plastic surgery Plastic surgery is a surgical specialty involving the restoration, reconstruction or alteration of the human body. It can be divided into two main categories: reconstructive surgery and cosmetic surgery. Reconstructive surgery includes cranio ...

, as one of the three mechanisms by which skin grafts take at the host site. Blood vessels from the recipient site are believed to connect with those of the graft in order to restore vascularity.

Species

Inosculation is most common among the following taxa due to their thin bark: *

Apple An apple is an edible fruit produced by an apple tree (''Malus domestica''). Apple trees are cultivated worldwide and are the most widely grown species in the genus '' Malus''. The tree originated in Central Asia, where its wild ancest ...

Almond The almond (''Prunus amygdalus'', syn. ''Prunus dulcis'') is a species of tree native to Iran and surrounding countries, including the Levant. The almond is also the name of the edible and widely cultivated seed of this tree. Within the genu ...

Ash Ash or ashes are the solid remnants of fires. Specifically, ''ash'' refers to all non-aqueous, non-gaseous residues that remain after something burns. In analytical chemistry, to analyse the mineral and metal content of chemical samples, ash ...

Beech Beech (''Fagus'') is a genus of deciduous trees in the family Fagaceae, native to temperate Europe, Asia, and North America. Recent classifications recognize 10 to 13 species in two distinct subgenera, ''Engleriana'' and ''Fagus''. The ''Engl ...

* Crepe myrtle *

Chestnut The chestnuts are the deciduous trees and shrubs in the genus ''Castanea'', in the beech family Fagaceae. They are native to temperate regions of the Northern Hemisphere. The name also refers to the edible nuts they produce. The unrel ...

Dogwood ''Cornus'' is a genus of about 30–60 species of woody plants in the family Cornaceae, commonly known as dogwoods, which can generally be distinguished by their blossoms, berries, and distinctive bark. Most are deciduous trees or ...

* Elm *

Ficus ''Ficus'' ( or ) is a genus of about 850 species of woody trees, shrubs, vines, epiphytes and hemiepiphytes in the family Moraceae. Collectively known as fig trees or figs, they are native throughout the tropics with a few species extendi ...

Grape A grape is a fruit, botanically a berry, of the deciduous woody vines of the flowering plant genus '' Vitis''. Grapes are a non- climacteric type of fruit, generally occurring in clusters. The cultivation of grapes began perhaps 8,000 years a ...

Hazelnut The hazelnut is the fruit of the hazel tree and therefore includes any of the nuts deriving from species of the genus '' Corylus'', especially the nuts of the species ''Corylus avellana''. They are also known as cobnuts or filberts according ...

Hornbeam Hornbeams are hardwood trees in the flowering plant genus ''Carpinus'' in the birch family Betulaceae. The 30–40 species occur across much of the temperate regions of the Northern Hemisphere. Origin of names The common English name ''hornbeam ...

Laburnum ''Laburnum'', sometimes called golden chain or golden rain, is a genus of two species of small trees in the subfamily Faboideae of the pea family Fabaceae. The species are ''Laburnum anagyroides''—common laburnum and ''Laburnum alpinum''� ...

* Linden *

Maple ''Acer'' () is a genus of trees and shrubs commonly known as maples. The genus is placed in the family Sapindaceae.Stevens, P. F. (2001 onwards). Angiosperm Phylogeny Website. Version 9, June 2008 nd more or less continuously updated since h ...

Norway spruce ''Picea abies'', the Norway spruce or European spruce, is a species of spruce native to Northern, Central and Eastern Europe. It has branchlets that typically hang downwards, and the largest cones of any spruce, 9–17 cm long. It is very close ...

Olive The olive, botanical name ''Olea europaea'', meaning 'European olive' in Latin, is a species of small tree or shrub in the family Oleaceae, found traditionally in the Mediterranean Basin. When in shrub form, it is known as ''Olea europaea'' ' ...

Peach The peach (''Prunus persica'') is a deciduous tree first domesticated and cultivated in Zhejiang province of Eastern China. It bears edible juicy fruits with various characteristics, most called peaches and others (the glossy-skinned, n ...

Pear Pears are fruits produced and consumed around the world, growing on a tree and harvested in the Northern Hemisphere in late summer into October. The pear tree and shrub are a species of genus ''Pyrus'' , in the Family (biology), family Rosacea ...

Privet A privet is a flowering plant in the genus ''Ligustrum''. The genus contains about 50 species of erect, deciduous or evergreen shrubs, sometimes forming small or medium-sized trees, native to Europe, north Africa, Asia, many introduced and nat ...

River red gum ''Eucalyptus camaldulensis'', commonly known as the river red gum, is a tree that is endemic to Australia. It has smooth white or cream-coloured bark, lance-shaped or curved adult leaves, flower buds in groups of seven or nine, white flowers an ...

Sycamore Sycamore is a name which has been applied to several types of trees, but with somewhat similar leaf forms. The name derives from the ancient Greek ' (''sūkomoros'') meaning "fig-mulberry". Species of trees known as sycamore: * ''Acer pseudoplata ...

Willow Willows, also called sallows and osiers, from the genus ''Salix'', comprise around 400 speciesMabberley, D.J. 1997. The Plant Book, Cambridge University Press #2: Cambridge. of typically deciduous trees and shrubs, found primarily on moist so ...

Wisteria ''Wisteria'' is a genus of flowering plants in the legume family, Fabaceae (Leguminosae), that includes ten species of woody twining vines that are native to China, Japan, Korea, Vietnam, Southern Canada, the Eastern United States, and north ...

Conjoined trees

Two trees may grow to their mature size adjacent to each other and seemingly grow together or conjoin, demonstrating inosculation. These may be of the same species or even of different genera or families, depending on whether the two trees have become truly grafted together (once the

of two trees touches, they self-graft and grow together). Usually grafting is only between two trees of the same or closely related species or genera, but the appearance of grafting can be given by two trees that are physically touching, rubbing, intertwined, or entangled. Both conifers and deciduous trees can become conjoined. Beech trees in particular are frequent conjoiners, as is blackthorn (''Prunus spinosa''). Husband and Wife trees - detail

Such trees are often colloquially referred to as "husband and wife" trees, or "marriage trees". The straightforward application of the term comes from the obvious unification of two separate individual trees, although a more humorous use of the term relates to the sexually suggestive appearance of some natural examples. There may be a degree of religious intent, as some cults are organized around beliefs that trees contain a hidden or sacred power to cure or to enhance fertility, or that they contain the souls of ancestors or of the unborn.

Examples

At the ruined Lynncraigs Farm,

Dalry, North Ayrshire Dalry () is a small town in the Garnock Valley in Ayrshire, Scotland. Drakemyre, North Ayrshire, Drakemyre is a northern suburb. History Dalry (from gd, Dail Ruighe, 'the haugh at the slope') is a small settlement on the Rye Burn. Its history ...

Scotland Scotland (, ) is a country that is part of the United Kingdom. Covering the northern third of the island of Great Britain, mainland Scotland has a border with England to the southeast and is otherwise surrounded by the Atlantic Ocean to ...

, a blackthorn (''Prunus spinosa''), standing in the old farm garden, shows signs of having been deliberately grafted. On his ''Tour of Scotland'', published in 1800, T. Garnett notes a tree near

Inveraray Inveraray ( or ; gd, Inbhir Aora meaning "mouth of the Aray") is a town in Argyll and Bute, Scotland. It is on the western shore of Loch Fyne, near its head, and on the A83 road. It is a former royal burgh, the traditional county town of Arg ...

that the locals called the Marriage tree, formed from a lime tree with two trunks that have been joined by a branch in the manner of a person putting an arm around another (se
illustration
as would a married couple. On the way to the Heavenly Lake near Urumqi in China are a pair of trees that local people have called the Husband and Wife trees because they are connected by a living branch. The Tatajia Husband and Wife trees are in

Taiwan Taiwan, officially the Republic of China (ROC), is a country in East Asia, at the junction of the East and South China Seas in the northwestern Pacific Ocean, with the People's Republic of China (PRC) to the northwest, Japan to the no ...

and in Yakushima, Kagoshima-ken,

Japan Japan ( ja, 日本, or , and formally , ''Nihonkoku'') is an island country in East Asia. It is situated in the northwest Pacific Ocean, and is bordered on the west by the Sea of Japan, while extending from the Sea of Okhotsk in the n ...

, are a pair of Husband and Wife trees formed from conjoined cedars. In Lambeg, Co. Down, slightly north of Wolfenden's Bridge, stand two beech trees (see 'Gallery') at the entrance to Chrome Hill, on the Lambeg to Ballyskeagh road. In the late 18th century,

John Wesley John Wesley (; 2 March 1791) was an English cleric, theologian, and evangelist who was a leader of a revival movement within the Church of England known as Methodism. The societies he founded became the dominant form of the independent Meth ...

was staying at Chrome Hill and decided to weave together two young beech trees to act as a symbol of unity between the

Methodist Church Methodism, also called the Methodist movement, is a group of historically related denominations of Protestant Christianity whose origins, doctrine and practice derive from the life and teachings of John Wesley. George Whitefield and John's ...

and the

Church of Ireland The Church of Ireland ( ga, Eaglais na hÉireann, ; sco, label= Ulster-Scots, Kirk o Airlann, ) is a Christian church in Ireland and an autonomous province of the Anglican Communion. It is organised on an all-Ireland basis and is the sec ...

. At Doonholm near

Ayr Ayr (; sco, Ayr; gd, Inbhir Àir, "Mouth of the River Ayr") is a town situated on the southwest coast of Scotland. It is the administrative centre of the South Ayrshire council area and the historic county town of Ayrshire. With a population ...

an ancient sycamore maple (''

Acer pseudoplatanus ''Acer pseudoplatanus'', known as the sycamore in the British Isles and as the sycamore maple in the United States, is a species of flowering plant in the soapberry and lychee family Sapindaceae. It is a large deciduous, broad-leaved tree, t ...

'') was famous for the multiple fusion of its boughs that gave it a unique appearance and greatly strengthened it.MacArthur, Page 81

Gallery

File:John Wesley's beech trees, Lambeg, Co. Down - geograph.org.uk - 165436.jpg, The John Wesley tree File:Acer pseudoplatanus exhibiting inosculation.JPG, Conjoined sycamore maples File:Inosculated Sycamore trees.JPG, ''Acer pseudoplatanus'' showing inosculation File:Beech tree trunk inosculation.JPG, Beech tree trunks conjoined File:The Marriage Tree.jpg, Garnett's 18th century "Marriage tree" File:Willow inosculation.JPG, Inosculation of willow ( ''Salix'' sp.) File:Beech tree root inosculation.JPG, Conjoined beech tree roots File:Beech tree branch inosculation.JPG, The classic "husband and wife" tree with branches conjoined File:Fused chestnut trees - 2 - Auró.JPG, Fused chestnut trees showing a bark pocket (''

Castanea sativa ''Castanea sativa'', the sweet chestnut, Spanish chestnut or just chestnut, is a species of tree in the family Fagaceae, native to Southern Europe and Asia Minor, and widely cultivated throughout the Temperate climate, temperate world. A substa ...

'') File:Fused ashtrees - Auró.JPG, Fused ash trees (''

Fraxinus excelsior ''Fraxinus excelsior'', known as the ash, or European ash or common ash to distinguish it from other types of ash, is a flowering plant species in the olive family Oleaceae. It is native throughout mainland Europe east to the Caucasus and Albor ...

'') File:Fused ashtrees side view - Auró.JPG, Fused ash trees, side view (''

'') File:Inosculation of Sycamore (Platanus occidentalis).jpg, Fused sycamore trees (''

Platanus occidentalis ''Platanus occidentalis'', also known as American sycamore, American planetree, western plane, occidental plane, buttonwood, and water beech, is a species of ''Platanus'' native to the eastern and central United States, the mountains of northeas ...

'') File:Vermont 2015.jpg, In Vermont File:-67wiki.jpg, The fused tree looks like a single tree. File:Picea abies European spurce Inosculation case, photo by Nik Barte, 4154 Dolomites Italy 2018.jpg, Inosculation case, ''Picea abies'' (European spruce), Dolomites

References

Notes

Sources

* Garnett, T. (1800). ''Observations on a Tour of the Highlands and part of the Western Isles of Scotland''. London : Cadell & Davies. * MacArthur, Wilson. (1952). ''The River Doon''. London : Cassell & Co. Ltd. * Morton, John (1712). ''The Natural History of Northhamptonshire.'' London : R.Knaplock.

External links

{{commons category, Inosculation, Husband and Wife tree
Video footage of Gemel trees in Ayrshire

Horticulture Plant physiology