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, e.g., including only woody plants with secondary growth, only ...

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

grafting Grafting or graftage is a horticulture, 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 roots ...

. 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 A species () is often defined as the largest group of organisms in which any two individuals of the appropriate sexes or mating types can produce fertile offspring, typically by sexual reproduction. It is the basic unit of Taxonomy (biology), ...

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 (: cambiums or cambia), 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 whic ...

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. The term ''inosculation'' is also used in the context of plastic surgery, 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 a round, edible fruit produced by an apple tree (''Malus'' spp.). Fruit trees of the orchard or domestic apple (''Malus domestica''), the most widely grown in the genus, are agriculture, cultivated worldwide. The tree originated ...

Almond The almond (''Prunus amygdalus'', Synonym (taxonomy)#Botany, syn. ''Prunus dulcis'') is a species of tree from the genus ''Prunus''. Along with the peach, it is classified in the subgenus ''Amygdalus'', distinguished from the other subgenera ...

* Ash *

Beech Beech (genus ''Fagus'') is a genus of deciduous trees in the family Fagaceae, native to subtropical (accessory forest element) and temperate (as dominant element of Mesophyte, mesophytic forests) Eurasia and North America. There are 14 accepted ...

Crepe myrtle ''Lagerstroemia'' (), commonly known as crape myrtle (also spelled crepe myrtle or crêpe myrtle), is a genus of around 50 species of deciduous and evergreen trees and shrubs native to the Indian subcontinent, southeast Asia, northern Australia ...

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

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

Elm Elms are deciduous and semi-deciduous trees comprising the genus ''Ulmus'' in the family Ulmaceae. They are distributed over most of the Northern Hemisphere, inhabiting the temperate and tropical- montane regions of North America and Eurasia, ...

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

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 approximately 8,0 ...

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 to ...

Hornbeam Hornbeams are hardwood trees in the plant genus ''Carpinus'' in the family Betulaceae. Its species occur across much of the temperateness, temperate regions of the Northern Hemisphere. Common names The common English name ''hornbeam'' derives ...

* Laburnum * Linden *

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

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 clo ...

Olive The olive, botanical name ''Olea europaea'' ("European olive"), is a species of Subtropics, subtropical evergreen tree in the Family (biology), family Oleaceae. Originating in Anatolia, Asia Minor, it is abundant throughout the Mediterranean ...

Peach The peach (''Prunus persica'') is a deciduous tree first domesticated and Agriculture, cultivated in China. It bears edible juicy fruits with various characteristics, most called peaches and the glossy-skinned, non-fuzzy varieties called necta ...

Pear Pears are fruits produced and consumed around the world, growing on a tree and harvested in late summer into mid-autumn. The pear tree and shrub are a species of genus ''Pyrus'' , in the Family (biology), family Rosaceae, bearing the Pome, po ...

Privet A privet is a flowering plant in the genus ''Ligustrum''. The genus contains about 50 species of erect, deciduous or evergreen shrubs or trees, with a native distribution from Europe to tropical and subtropical Asia, and with one species each ...

* River red gum *

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 () meaning . Species of otherwise unrelated trees known as sycamore: * ''Acer pseudoplatanus'', a ...

Willow Willows, also called sallows and osiers, of the genus ''Salix'', comprise around 350 species (plus numerous hybrids) of typically deciduous trees and shrubs, found primarily on moist soils in cold and temperate regions. Most species are known ...

Wisteria ''Wisteria'' is a genus of flowering plants in the legume family, Fabaceae (Leguminosae). The genus includes four species of woody twining vines that are native to China, Japan, Korea, Vietnam, southern Canada, the Eastern United States, and nor ...

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

On his ''Tour of Scotland'', published in 1800, T. Garnett notes a tree near

Inveraray Inveraray ( or ; meaning "mouth of the Aray") is a town in Argyll and Bute, Scotland. Located on the western shore of Loch Fyne, near its head, Inveraray is a former royal burgh and known affectionately as "The Capital of Argyll." It is the ...

that the locals called the Marriage tree, formed from a

lime tree ''Tilia'' is a genus of about 30 species of trees or bushes, native throughout most of the temperate Northern Hemisphere. The tree is known as linden for the European species, and basswood for North American species. In Great Britain and Irelan ...

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. The main geography of Taiwan, island of Taiwan, also known as ''Formosa'', lies between the East China Sea, East and South China Seas in the northwestern Pacific Ocea ...

and in Yakushima, Kagoshima-ken,

Japan Japan is an island country in East Asia. Located in the Pacific Ocean off the northeast coast of the Asia, Asian mainland, it is bordered on the west by the Sea of Japan and extends from the Sea of Okhotsk in the north to the East China Sea ...

, 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, Christian theology, theologian, and Evangelism, evangelist who was a principal leader of a Christian revival, revival movement within the Church of England known as Methodism. The societies ...

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 Protestant Christianity, Christian Christian tradition, tradition whose origins, doctrine and practice derive from the life and teachings of John Wesley. George Whitefield and John's brother ...

and the

Church of Ireland The Church of Ireland (, ; , ) is a Christian church in Ireland, and an autonomy, autonomous province of the Anglican Communion. It is organised on an all-Ireland basis and is the Christianity in Ireland, second-largest Christian church on the ...

. At Doonholm near Ayr 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 maple native to Central Europe and Western Asia. It is a large deciduous, broad-leaved tree, tolerant of wind an ...

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

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, A classic "husband and wife" tree with branches conjoined File:Fused chestnut trees - 2 - Auró.JPG, Fused chestnut trees showing a bark pocket (''

Castanea sativa The sweet chestnut (''Castanea sativa''), also known as the Spanish chestnut or European chestnut, is a species of tree in the family Fagaceae, native to Southern Europe and Asia Minor, and widely cultivated throughout the Temperate climate, te ...

'') 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 Alb ...

'') 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 northeast ...

'') 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

* * *

External links

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

Horticulture Plant physiology