Editing Laburnum

{{Short description|Genus of plants}}
{{Other uses}}
{{Use dmy dates|date=July 2020}}
{{Automatic taxobox
| image = Laburnum_anagyroides2.jpg
| image_caption = Common laburnum – flowers
| taxon = Laburnum
| authority = [[Philipp Conrad Fabricius|Fabr.]]
| subdivision_ranks = Species
| subdivision = See text
}}

'''''Laburnum''''', sometimes called '''golden chain''' or '''golden rain''', is a genus of two species of small [[tree]]s in the subfamily [[Faboideae]] of the pea family [[Fabaceae]]. The species are ''[[Laburnum anagyroides]]''—'''common laburnum''' and ''[[Laburnum alpinum]]''—'''alpine laburnum'''. They are native to the mountains of southern [[Europe]] from [[France]] to the [[Balkans]].

Some botanists include a third species, ''Laburnum caramanicum'', but this native of southeast Europe and [[Anatolia]] is usually treated in a distinct genus ''[[Podocytisus]]'', more closely allied to the ''[[Genisteae]]'' (brooms).

==Description==
The ''Laburnum'' trees are [[deciduous]]. The leaves are trifoliate, somewhat like a [[clover]]; the leaflets are typically {{convert|2|–|3|cm|in|1|round=0.5|abbr=on}} long in ''L. anagyroides'' and {{convert|4|–|5|cm|in|round=0.5|abbr=on}} long in ''L. alpinum''.

They have yellow pea-[[flower]]s in pendulous leafless [[raceme]]s {{convert|10|–|40|cm|in|round=0.5|abbr=on}} long in spring, which makes them very popular garden trees. In ''L. anagyroides'', the racemes are {{convert|10|–|20|cm|in|round=0.5|abbr=on}} long, with densely packed flowers; in ''L. alpinum'' the racemes are {{convert|20|–|30|cm|in|round=0.5|abbr=on}} long, but with the flowers sparsely along the raceme.<ref>Parnell, J. and Curtis, T. 2012. ''Webb's An Irish Flora''. Cork University Press. {{ISBN|978-185918-4783}}</ref> The fruit develops as a [[Legume|pod]] and is extremely poisonous.<ref>Kilbracken, J. 1989. ''Easy way guide Trees''. Larousse. {{ISBN|0-7523-0027-X}}</ref>

The yellow flowers are responsible for the old poetic name 'golden chain tree' (also written as golden chaintree or goldenchain tree).
[[Image:Laburnum anagyroides flowering.jpg|thumb|left|Laburnum tree in full flower]]
All parts of the plant are [[poison]]ous, although mortality is very rare.<ref>{{cite journal  | author = Forrester R.M. | title = Have you Eaten Laburnum? | year = 1979 | journal = The Lancet| volume = 313 | issue = 8125 | pages = 1073 | doi = 10.1016/S0140-6736(79)92963-5 | pmid = 86787 | s2cid = 38961471 }}</ref> 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 contraction|tetanic]]. The main toxin in the plant is [[cytisine]], a nicotinic receptor [[agonist]].

It is used as a food plant by the [[larva]]e of some [[Lepidoptera]] species, including the [[Palearctic]] moth, the [[buff-tip]].

==Species==

===Accepted binomials===
''Laburnum'' comprises the following species:<ref>{{cite web | url = http://www.ildis.org/LegumeWeb?version~10.01&genus~Laburnum&species~ | title = ILDIS LegumeWeb entry for ''Laburnum'' | author = <!--Staff writer(s); no by-line.--> | website = International Legume Database & Information Service | publisher = Cardiff School of Computer Science & Informatics | accessdate = 11 April 2014 }}</ref><ref>{{cite web | url = http://www.ars-grin.gov/cgi-bin/npgs/html/splist.pl?6427 | title = GRIN species records of ''Laburnum'' | author = USDA | author-link = USDA | author2 = ARS | author2-link = Agricultural Research Service | author3 = National Genetic Resources Program | website = [[Germplasm Resources Information Network]]—(GRIN) [Online Database] | publisher = [[Henry A. Wallace Beltsville Agricultural Research Center|National Germplasm Resources Laboratory]], Beltsville, Maryland | accessdate = 11 April 2014 | url-status = dead | archiveurl = https://web.archive.org/web/20150924122101/http://www.ars-grin.gov/cgi-bin/npgs/html/splist.pl?6427 | archivedate = 24 September 2015}}</ref><ref name="PlantList">{{cite web | url = http://www.theplantlist.org/1.1/browse/A/Leguminosae/Laburnum/ | title = The Plant List entry for ''Laburnum'' | date = 2013 | website = [[The Plant List]] | publisher = [[Royal Botanic Gardens, Kew]] and the [[Missouri Botanical Garden]] | accessdate = 11 April 2014 }}</ref>
* ''[[Laburnum alpinum]]'' <small>(Mill.) Bercht. & J. Presl</small>
* ''[[Laburnum anagyroides]]'' <small>Medik.</small>
<!-- Laburnum caramanicum was reclassified as Podocytisus caramanicus. -->
<!-- Laburnum platycarpum was reclassified as Hesperolaburnum platycarpum. -->
<!-- Laburnum vulgare was reclassified as Laburnum anagyroides. -->

===Species names with uncertain taxonomic status===
The status of the following species is unresolved:<ref name="PlantList" />
{{div col|colwidth=300px}}
* ''Laburnum album'' <small>J.Presl</small>
* ''Laburnum arboreum'' <small>J.Presl</small>
* ''Laburnum biflorum'' <small>G.Nicholson</small>
* ''Laburnum fragrans'' <small>Griseb.</small>
* ''Laburnum grandiflorum'' <small>(DC.) J.Presl</small>
* ''Laburnum heuffelii'' <small>Wierzb. ex Fuss</small>
* ''Laburnum ianigerum'' <small>J. Presl</small>
* ''Laburnum intermedium'' <small>Dippel</small>
* ''Laburnum jacquinianum'' <small>Dalla Torre & Sarnth.</small>
* ''Laburnum jaquinianum'' <small>Dieck</small>
* ''Laburnum laburnum'' <small>(L.) Voss</small>
* ''Laburnum laburnum'' <small>Dörfl.</small>
* ''Laburnum lanigerum'' <small>J.Presl</small>
* ''Laburnum linneanum'' <small>Dieck</small>
* ''Laburnum monadelphum'' <small>Pritz.</small>
* ''Laburnum nigricans'' <small>J.Presl</small>
* ''Laburnum nigricanum'' <small>Fuss</small>
* ''Laburnum nubigenum'' <small>J.Presl</small>
* ''Laburnum patens'' <small>J.Presl</small>
* ''Laburnum pendulum'' <small>Raf.</small>
* ''Laburnum praecox'' <small>Fuss</small>
* ''Laburnum purpurascens'' <small>hort. & Vilm.</small>
* ''Laburnum purpureum'' <small>(Scop.) Drapiez</small>
* ''Laburnum ramentaceum'' <small>(Sieber) K.Koch</small>
* ''Laburnum rochelii'' <small>Wierzb. ex Fuss</small>
* ''Laburnum serotinum'' <small>Hort. ex Dippel</small>
* ''Laburnum sessilifolium'' <small>J.Presl</small>
* ''Laburnum spinosum'' <small>J.Presl</small>
* ''Laburnum tardiflorum'' <small>auct.</small>
* ''Laburnum triflorum'' <small>J.Presl</small>
* ''Laburnum variabile'' <small>hort. & Vilm.</small>
* ''Laburnum weldeni'' <small>Griseb. ex Lavall.</small>
* ''Laburnum weldenii'' <small>Griseb. ex Lavallée</small>
{{div col end}}

===Hybrids===
The following hybrids have been described:<ref name="PlantList" />
* [[Laburnum × watereri|''Laburnum'' × ''watereri'']] <small>(Wettst.) Dippel</small> (''L. alpinum'' × ''L. anagyroides'')

There is also a [[graft-chimaera]], [[+ Laburnocytisus 'Adamii'|+ ''Laburnocytisus'' 'Adamii']] <small>Lavallée</small>.

==Uses==

===Woodworking===
''Laburnum'' has historically been used for cabinetmaking and inlay, as well as for musical instruments. In addition to such [[wind instruments]] as [[Recorder (musical instrument)|recorders]] and [[flutes]], it was a popular wood for [[Great Highland Bagpipe]]s<ref name="Rendle1969">{{cite book | author = Rendle BJ | title = World Timbers: Europe and Africa | volume = 1 | url = https://books.google.com/books?id=JIhGAAAAYAAJ| year = 1969 | publisher = Univ of Toronto Press | page = 40 | isbn = 978-0802015709 }}</ref> before taste turned to imported dense tropical hardwoods such as ''[[Brya ebenus]]'' (cocus wood), [[ebony]], and ''[[Dalbergia melanoxylon]]'' (African monkeywood).<ref name="Dickson2009">{{cite book | author = Dickson J. | title = The Highland bagpipe: music, history, tradition | url = https://books.google.com/books?id=JOfk2YpundEC&pg=PA50|year=2009| publisher = Ashgate Publishing, Ltd. | isbn = 978-0-7546-6669-1 | page = 50 }}</ref> 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. [[File:Freshly cross cut Laburnum with heart-wood.jpg|thumb|Freshly cross cut laburnum with visible heart-wood]]

===Cultivation===
''Laburnum'' [[species]] and [[Hybrid (biology)#Hybrid plants|hybrid]]s are cultivated as [[Ornamental plant#Trees|ornamental trees]] for gardens and parks. They are also trained as [[espalier]]s on [[pergola]]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.<ref>{{cite book| title=Sunset Western Garden Book | editor=Kathleen Norris Brenzel | year=2007 | page=429 }}</ref> 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 climate|Oceanic climates]] like those of the [[Pacific Northwest]] and [[Northern Europe]].<ref>{{cite web | url = http://www.missouribotanicalgarden.org/PlantFinder/PlantFinderDetails.aspx?kempercode=c115| title=Laburnum x watereri 'Vossii'|publisher=Missouribotanicalgarden.com| access-date=18 December 2017}}</ref> ''Laburnum'' trees are ubiquitous in [[England]], [[Wales]], [[Scotland]] and [[Ireland]], 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]]'s [[Award of Garden Merit]].<ref>{{cite web | title = Plant Selector—''Laburnum'' ×''watereri'' 'Vossii' | url = http://apps.rhs.org.uk/plantselector/plant?plantid=1105 | publisher = Royal Horticultural Society | accessdate = 20 May 2013 | archive-date = 13 April 2014 | archive-url = https://web.archive.org/web/20140413150139/http://apps.rhs.org.uk/plantselector/plant?plantid=1105 | url-status = dead }}</ref><ref>{{cite web  | url= https://www.rhs.org.uk/plants/pdfs/agm-lists/agm-ornamentals.pdf | title = AGM Plants - Ornamental | date = July 2017 | page = 57 | publisher = Royal Horticultural Society | accessdate = 17 March 2018}}</ref>

==References==
{{Reflist}}

==External links==
* [http://rbg-web2.rbge.org.uk/cgi-bin/nph-readbtree.pl/feout?FAMILY_XREF=&GENUS_XREF=Laburnum&SPECIES_XREF=&TAXON_NAME_XREF=&RANK= Flora Europaea: ''Laburnum'']
* [https://web.archive.org/web/20140517100307/http://ildis.org/ ILDIS Legume Database]
* {{usurped|1=[https://web.archive.org/web/20040925221835/http://www.haworth-village.org.uk/nature/time-lapse/time-lapse.asp?pic=16 Laburnum tree video]}} — ''time lapse of a year in the life of a Laburnum tree''.
* [http://www.botanical.com/botanical/mgmh/l/labrun02.html Grieve, 'A Modern Herbal' (1931)]


{{Commons category-inline|Laburnum}}

{{Taxonbar|from=Q147184}}

[[Category:Genisteae]]
[[Category:Fabaceae genera]]
[[Category:Trees of Europe]]
[[Category:Flora of Europe]]
[[Category:Flora of Italy]]
[[Category:Garden plants of Europe]]
[[Category:Ornamental trees]]