''Laburnum'', sometimes called golden chain or golden rain, is a genus of two species of small
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 in the subfamily
Faboideae
The Faboideae are a subfamily of the flowering plant family Fabaceae or Leguminosae. An acceptable alternative name for the subfamily is Papilionoideae, or Papilionaceae when this group of plants is treated as a family.
This subfamily is wide ...
of the pea family
. The species are ''
Laburnum anagyroides
''Laburnum anagyroides'' ( syn. ''Cytisus laburnum''), the common laburnum, golden chain or golden rain, is a species of flowering plant in the subfamily Faboideae, and genus ''Laburnum''. '' Laburnum alpinum'' is closely related. It is native t ...
''—common laburnum and ''
Laburnum alpinum''—alpine laburnum. They are native to the mountains of southern
Europe
Europe is a large peninsula conventionally considered a continent in its own right because of its great physical size and the weight of its history and traditions. Europe is also considered a Continent#Subcontinents, subcontinent of Eurasia ...
from
France
France (), officially the French Republic ( ), is a country primarily located in Western Europe. It also comprises of Overseas France, overseas regions and territories in the Americas and the Atlantic Ocean, Atlantic, Pacific Ocean, Pac ...
to the
Balkans
The Balkans ( ), also known as the Balkan Peninsula, is a geographical area in southeastern Europe with various geographical and historical definitions. The region takes its name from the Balkan Mountains that stretch throughout the who ...
.
Some botanists include a third species, ''Laburnum caramanicum'', but this native of southeast Europe and
Anatolia
Anatolia, tr, Anadolu Yarımadası), and the Anatolian plateau, also known as Asia Minor, is a large peninsula in Western Asia and the westernmost protrusion of the Asian continent. It constitutes the major part of modern-day Turkey. The re ...
is usually treated in a distinct genus ''
Podocytisus
''Podocytisus caramanicus'' is a species of flowering plants in the family Fabaceae. It belongs to the subfamily Faboideae
The Faboideae are a subfamily of the flowering plant family Fabaceae or Leguminosae. An acceptable alternative name f ...
'', more closely allied to the ''
Genisteae
Genisteae is a tribe of trees, shrubs and herbaceous plants in the subfamily Faboideae of the family Fabaceae. It includes a number of well-known plants including broom, lupine (lupin), gorse and laburnum.
The tribe's greatest diversity is in ...
'' (brooms).
Description
The ''Laburnum'' trees are
deciduous
In the fields of horticulture and Botany, the term ''deciduous'' () means "falling off at maturity" and "tending to fall off", in reference to trees and shrubs that seasonally shed leaves, usually in the autumn; to the shedding of petals, aft ...
. The leaves are trifoliate, somewhat like a
clover
Clover or trefoil are common names for plants of the genus ''Trifolium'' (from Latin ''tres'' 'three' + ''folium'' 'leaf'), consisting of about 300 species of flowering plants in the legume or pea family Fabaceae originating in Europe. The genus ...
; the leaflets are typically long in ''L. anagyroides'' and long in ''L. alpinum''.
They have yellow pea-
flower
A flower, sometimes known as a bloom or blossom, is the reproductive structure found in flowering plants (plants of the division Angiospermae). The biological function of a flower is to facilitate reproduction, usually by providing a mechani ...
s in pendulous leafless
raceme
A raceme ( or ) or racemoid is an unbranched, indeterminate type of inflorescence bearing flowers having short floral stalks along the shoots that bear the flowers. The oldest flowers grow close to the base and new flowers are produced as the s ...
s long in spring, which makes them very popular garden trees. In ''L. anagyroides'', the racemes are long, with densely packed flowers; in ''L. alpinum'' the racemes are long, but with the flowers sparsely along the raceme. The fruit develops as a
pod and is extremely poisonous.
The yellow flowers are responsible for the old poetic name 'golden chain tree' (also written as golden chaintree or goldenchain tree).
All parts of the plant are
poison
Poison is a chemical substance that has a detrimental effect to life. The term is used in a wide range of scientific fields and industries, where it is often specifically defined. It may also be applied colloquially or figuratively, with a broa ...
ous, although mortality is very rare. Symptoms of laburnum poisoning may include intense sleepiness, vomiting, convulsive movements, coma, slight frothing at the mouth and unequally dilated pupils. In some cases, diarrhea is very severe, and at times the convulsions are markedly
tetanic. The main toxin in the plant is
cytisine
Cytisine, also known as baptitoxine, cytisinicline, or sophorine, is an alkaloid that occurs naturally in several plant genera, such as ''Laburnum'' and ''Cytisus'' of the family Fabaceae. It has been used medically to help with smoking cessati ...
, a nicotinic receptor
agonist
An agonist is a chemical that activates a receptor to produce a biological response. Receptors are cellular proteins whose activation causes the cell to modify what it is currently doing. In contrast, an antagonist blocks the action of the ago ...
.
It is used as a food plant by the
larva
A larva (; plural larvae ) is a distinct juvenile form many animals undergo before metamorphosis into adults. Animals with indirect development such as insects, amphibians, or cnidarians typically have a larval phase of their life cycle.
The ...
e of some
Lepidoptera
Lepidoptera ( ) is an order (biology), order of insects that includes butterfly, butterflies and moths (both are called lepidopterans). About 180,000 species of the Lepidoptera are described, in 126 Family (biology), families and 46 Taxonomic r ...
species, including the
Palearctic
The Palearctic or Palaearctic is the largest of the eight biogeographic realms of the Earth. It stretches across all of Eurasia north of the foothills of the Himalayas, and North Africa.
The realm consists of several bioregions: the Euro-Sibe ...
moth, the
buff-tip
The buff-tip (''Phalera bucephala'') is a moth of the family Notodontidae. It is found throughout Europe and in Asia to eastern Siberia. The species was first described by Carl Linnaeus in his 1758 10th edition of ''Systema Naturae''.
Descrip ...
.
Species
Accepted binomials
''Laburnum'' comprises the following species:
* ''
Laburnum alpinum''
(Mill.) Bercht. & J. Presl
* ''
Laburnum anagyroides
''Laburnum anagyroides'' ( syn. ''Cytisus laburnum''), the common laburnum, golden chain or golden rain, is a species of flowering plant in the subfamily Faboideae, and genus ''Laburnum''. '' Laburnum alpinum'' is closely related. It is native t ...
''
Medik.
Species names with uncertain taxonomic status
The status of the following species is unresolved:
* ''Laburnum album''
J.Presl
* ''Laburnum arboreum''
J.Presl
* ''Laburnum biflorum''
G.Nicholson
* ''Laburnum fragrans''
Griseb.
* ''Laburnum grandiflorum''
(DC.) J.Presl
* ''Laburnum heuffelii''
Wierzb. ex Fuss
* ''Laburnum ianigerum''
J. Presl
* ''Laburnum intermedium''
Dippel
* ''Laburnum jacquinianum''
Dalla Torre & Sarnth.
* ''Laburnum jaquinianum''
Dieck
* ''Laburnum laburnum''
(L.) Voss
* ''Laburnum laburnum''
Dörfl.
* ''Laburnum lanigerum''
J.Presl
* ''Laburnum linneanum''
Dieck
* ''Laburnum monadelphum''
Pritz.
* ''Laburnum nigricans''
J.Presl
* ''Laburnum nigricanum''
Fuss
* ''Laburnum nubigenum''
J.Presl
* ''Laburnum patens''
J.Presl
* ''Laburnum pendulum''
Raf.
* ''Laburnum praecox''
Fuss
* ''Laburnum purpurascens''
hort. & Vilm.
* ''Laburnum purpureum''
(Scop.) Drapiez
* ''Laburnum ramentaceum''
(Sieber) K.Koch
* ''Laburnum rochelii''
Wierzb. ex Fuss
* ''Laburnum serotinum''
Hort. ex Dippel
* ''Laburnum sessilifolium''
J.Presl
* ''Laburnum spinosum''
J.Presl
* ''Laburnum tardiflorum''
auct.
* ''Laburnum triflorum''
J.Presl
* ''Laburnum variabile''
hort. & Vilm.
* ''Laburnum weldeni''
Griseb. ex Lavall.
* ''Laburnum weldenii''
Griseb. ex Lavallée
Hybrids
The following hybrids have been described:
*
''Laburnum'' × ''watereri'' (Wettst.) Dippel (''L. alpinum'' × ''L. anagyroides'')
There is also a
graft-chimaera
In horticulture, a graft-chimaera may arise in grafting at the point of contact between rootstock and scion and will have properties intermediate between those of its "parents". A graft-chimaera is not a true hybrid but a mixture of cells, each w ...
,
+ ''Laburnocytisus'' 'Adamii' Lavallée.
Uses
Woodworking
''Laburnum'' has historically been used for cabinetmaking and inlay, as well as for musical instruments. In addition to such wind instruments as recorders and flutes, it was a popular wood for
Great Highland Bagpipe
The Great Highland bagpipe ( gd, a' phìob mhòr "the great pipe") is a type of bagpipe native to Scotland, and the Scottish analogue to the Great Irish Warpipes. It has acquired widespread recognition through its usage in the British milit ...
s
before taste turned to imported dense tropical hardwoods such as ''
Brya ebenus'' (cocus wood),
ebony
Ebony is a dense black/brown hardwood, coming from several species in the genus ''Diospyros'', which also contains the persimmons. Unlike most woods, ebony is dense enough to sink in water. It is finely textured and has a mirror finish when pol ...
, and ''
Dalbergia melanoxylon
''Dalbergia melanoxylon'' (African blackwood, grenadilla, or mpingo) is a flowering plant in the family Fabaceae, native to seasonally dry regions of Africa from Senegal east to Eritrea and south to the north-eastern parts of South Africa. The ...
'' (African monkeywood).
The heart-wood of a laburnum may be used as a substitute for ebony or rosewood. It is very hard and a dark chocolate brown, with a butter-yellow sapwood.
Cultivation
''Laburnum''
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 appropriate s ...
and
hybrid
Hybrid may refer to:
Science
* Hybrid (biology), an offspring resulting from cross-breeding
** Hybrid grape, grape varieties produced by cross-breeding two ''Vitis'' species
** Hybridity, the property of a hybrid plant which is a union of two dif ...
s are cultivated as
ornamental trees
Ornamental plants or garden plants are plants that are primarily grown for their beauty but also for qualities such as scent or how they shape physical space. Many flowering plants and garden varieties tend to be specially bred cultivars that i ...
for gardens and parks. They are also trained as
espalier
Espalier ( or ) is the horticultural and ancient agricultural practice of controlling woody plant growth for the production of fruit, by pruning and tying branches to a frame. Plants are frequently shaped in formal patterns, flat against a struct ...
s on
pergola
A pergola is most commonly an outdoor garden feature forming a shaded walkway, passageway, or sitting area of vertical posts or pillars that usually support cross-beams and a sturdy open lattice, often upon which woody vines are trained. The ...
s, for ceilings of pendant flowers in season. In its natural form, ''Laburnum'' is a shrubby, multi-branched tree, but it is often pruned to maintain a single trunk which displays the smooth green bark.
Gardeners are advised to remove the spent seedpods after flowering because they sap the strength of the tree and are the most poisonous part. Generally ''Laburnum'' does not perform well in hot climates, and has a reduced life-span if grown in climates with warm winters. Afternoon shade and the occasional deep watering are advisable in areas with hot, dry summers. They do best in climates with moderate winter and summer temperatures, ideally
Oceanic
Oceanic may refer to:
*Of or relating to the ocean
*Of or relating to Oceania
**Oceanic climate
**Oceanic languages
**Oceanic person or people, also called "Pacific Islander(s)"
Places
* Oceanic, British Columbia, a settlement on Smith Island, ...
climates like those of the
Pacific Northwest
The Pacific Northwest (sometimes Cascadia, or simply abbreviated as PNW) is a geographic region in western North America bounded by its coastal waters of the Pacific Ocean to the west and, loosely, by the Rocky Mountains to the east. Though ...
and
Northern Europe
The northern region of Europe has several definitions. A restrictive definition may describe Northern Europe as being roughly north of the southern coast of the Baltic Sea, which is about 54th parallel north, 54°N, or may be based on other g ...
. ''Laburnum'' trees are ubiquitous in
England
England is a country that is part of the United Kingdom. It shares land borders with Wales to its west and Scotland to its north. The Irish Sea lies northwest and the Celtic Sea to the southwest. It is separated from continental Europe b ...
,
Wales
Wales ( cy, Cymru ) is a Countries of the United Kingdom, country that is part of the United Kingdom. It is bordered by England to the Wales–England border, east, the Irish Sea to the north and west, the Celtic Sea to the south west and the ...
,
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 the ...
and
Ireland
Ireland ( ; ga, Éire ; Ulster Scots dialect, Ulster-Scots: ) is an island in the Atlantic Ocean, North Atlantic Ocean, in Northwestern Europe, north-western Europe. It is separated from Great Britain to its east by the North Channel (Grea ...
, where they are commonly planted as lawn specimens or in shrub borders.
Most garden specimens are of the hybrid between the two species, ''Laburnum'' ×''watereri'' 'Vossii' (Voss's laburnum), which combines the longer racemes of ''L. alpinum'' with the denser flowers of ''L. anagyroides''; it also has the benefit of low seed production. It has gained the
Royal Horticultural Society
The Royal Horticultural Society (RHS), founded in 1804 as the Horticultural Society of London, is the UK's leading gardening charity.
The RHS promotes horticulture through its five gardens at Wisley (Surrey), Hyde Hall (Essex), Harlow Carr (Nort ...
's
Award of Garden Merit
The Award of Garden Merit (AGM) is a long-established annual award for plants by the British Royal Horticultural Society (RHS). It is based on assessment of the plants' performance under UK growing conditions.
History
The Award of Garden Merit ...
.
References
External links
Flora Europaea: ''Laburnum''ILDIS Legume DatabaseLaburnum tree video— ''time lapse of a year in the life of a Laburnum tree''.
{{Taxonbar, from=Q147184
Genisteae
Fabaceae genera
Trees of Europe
Flora of Europe
Flora of Italy
Garden plants of Europe
Ornamental trees