Acer opalus
Italian maple

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Italian maple (Acer opalus) is a medium-sized deciduous tree with a broad, rounded crown and lobed leaves. Native to southern and central Europe, its range includes the Iberian Peninsula, southern France, Italy, and parts of the western Balkans, where it typically grows in montane mixed forests on limestone or calcareous soils (Segarra-Moragues, Gleiser, and González-Candelas, 2008). It is particularly well adapted to Mediterranean climates, showing resilience in rocky, dry, and nutrient-poor environments. 

Italian maple is valued for its drought tolerance and ecological role in stabilizing soils and enriching biodiversity in warm-temperate woodland ecosystems. It thrives in sunny or semi-shaded areas and can regenerate in degraded forest edges. Its broad leaves turn striking yellow or reddish hues in autumn. Small, yellow-green flowers appear in early spring, followed by winged wind dispersed seeds (samaras). 

The wood of Italian maple is used locally for firewood or for making small tools, but it is not of major commercial importance. Valued for its modest size, attractive foliage, and adaptability to dry conditions, Italian maple is suitable for growing in gardens, parks, and urban green spaces. Despite its resilience, Italian maple is sensitive to intense browsing and competition. 

in situ genetic conservation unit−+
ex situ genetic conservation unit−+
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Acknowledgements

This distribution map has been developed by the European Commission Joint Research Centre (partly based on the EUFORGEN map) and released under Creative Commons Attribution 4.0 International (CC-BY 4.0)

Caudullo, Giovanni; Welk, Erik; San-Miguel-Ayanz, Jesús (2017). Chorological maps and data for the main European woody species. figshare. Collection. https://doi.org/10.6084/m9.figshare.c.2918528

 

The following experts have contributed to the development of the EUFORGEN distribution maps:

Fazia Krouchi (Algeria), Hasmik Ghalachyan (Armenia), Thomas Geburek (Austria), Berthold Heinze (Austria), Rudi Litschauer (Austria), Rudolf Litschauer (Austria), Michael Mengl (Austria), Ferdinand Müller (Austria), Franz Starlinger (Austria), Valida Ali-zade (Azerbaijan), Vahid Djalal Hajiyev (Azerbaijan), Karen Cox (Belgium), Bart De Cuyper (Belgium), Olivier Desteucq (Belgium), Patrick Mertens (Belgium), Jos Van Slycken (Belgium), An Vanden Broeck (Belgium), Kristine Vander Mijnsbrugge (Belgium), Dalibor Ballian (Bosnia and Herzegovina), Alexander H. Alexandrov (Bulgaria), Alexander Delkov (Bulgaria), Ivanova Denitsa Pandeva (Bulgaria), Peter Zhelev Stoyanov (Bulgaria), Joso Gracan (Croatia), Marilena Idzojtic (Croatia), Mladen Ivankovic (Croatia), Željka Ivanović (Croatia), Davorin Kajba (Croatia), Hrvoje Marjanovic (Croatia), Sanja Peric (Croatia), Andreas Christou (Cyprus), Xenophon Hadjikyriacou (Cyprus), Václav Buriánek (Czech Republic), Jan Chládek (Czech Republic), Josef Frýdl (Czech Republic), Petr Novotný (Czech Republic), Martin Slovacek (Czech Republic), Zdenek Špišek (Czech Republic), Karel Vancura (Czech Republic), Ulrik Bräuner (Denmark), Bjerne Ditlevsen (Denmark), Jon Kehlet Hansen (Denmark), Jan Svejgaard Jensen (Denmark), Kalev Jðgiste (Estonia), Tiit Maaten (Estonia), Raul Pihu (Estonia), Ülo Tamm (Estonia), Arvo Tullus (Estonia), Aivo Vares (Estonia), Teijo Nikkanen (Finland), Sanna Paanukoski (Finland), Mari Rusanen (Finland), Pekka Vakkari (Finland), Leena Yrjänä (Finland), Daniel Cambon (France), Eric Collin (France), Alexis Ducousso (France), Bruno Fady (France), François Lefèvre (France), Brigitte Musch (France), Sylvie Oddou-Muratorio (France), Luc E. Pâques (France), Julien Saudubray (France), Marc Villar (France), Vlatko Andonovski (FYR Macedonia), Dragi Pop-Stojanov (FYR Macedonia), Merab Machavariani (Georgia), Irina Tvauri (Georgia), Alexander Urushadze (Georgia), Bernd Degen (Germany), Jochen Kleinschmit (Germany), Armin König (Germany), Armin König (Germany), Volker Schneck (Germany), Richard Stephan (Germany), H. H. Kausch-Blecken Von Schmeling (Germany), Georg von Wühlisch (Germany), Iris Wagner (Germany), Heino Wolf (Germany), Paraskevi Alizoti (Greece), Filippos Aravanopoulos (Greece), Andreas Drouzas (Greece), Despina Paitaridou (Greece), Aristotelis C. Papageorgiou (Greece), Kostas Thanos (Greece), Sándor Bordács (Hungary), Csaba Mátyás (Hungary), László Nagy (Hungary), Thröstur Eysteinsson (Iceland), Adalsteinn Sigurgeirsson (Iceland), Halldór Sverrisson (Iceland), John Fennessy (Ireland), Ellen O'Connor (Ireland), Fulvio Ducci (Italy), Silvia Fineschi (Italy), Bartolomeo Schirone (Italy), Marco Cosimo Simeone (Italy), Giovanni Giuseppe Vendramin (Italy), Lorenzo Vietto (Italy), Janis Birgelis (Latvia), Virgilijus Baliuckas (Lithuania), Kestutis Cesnavicius (Lithuania), Darius Danusevicius (Lithuania), Valmantas Kundrotas (Lithuania), Alfas Pliûra (Lithuania), Darius Raudonius (Lithuania), Robert du Fays (Luxembourg), Myriam Heuertz (Luxembourg), Claude Parini (Luxembourg), Fred Trossen (Luxembourg), Frank Wolter (Luxembourg), Joseph Buhagiar (Malta), Eman Calleja (Malta), Ion Palancean (Moldova), Dragos Postolache (Moldova), Gheorghe Postolache (Moldova), Hassan Sbay (Morocco), Tor Myking (Norway), Tore Skrøppa (Norway), Anna Gugala (Poland), Jan Kowalczyk (Poland), Czeslaw Koziol (Poland), Jan Matras (Poland), Zbigniew Sobierajski (Poland), Maria Helena Almeida (Portugal), Filipe Costa e Silva (Portugal), Luís Reis (Portugal), Maria Carolina Varela (Portugal), Ioan Blada (Romania), Alexandru-Lucian Curtu (Romania), Lucian Dinca (Romania), Georgeta Mihai (Romania), Mihai Olaru (Romania), Gheorghe Parnuta (Romania), Natalia Demidova (Russian Federation), Mikhail V. Pridnya (Russian Federation), Andrey Prokazin (Russian Federation), Srdjan Bojovic (Serbia) , Vasilije Isajev (Serbia), Saša Orlovic (Serbia), Rudolf Bruchánik (Slovakia), Roman Longauer (Slovakia), Ladislav Paule (Slovakia), Gregor Bozič (Slovenia), Robert Brus (Slovenia), Katarina Celič (Slovenia), Hojka Kraigher (Slovenia), Andrej Verlič (Slovenia), Marjana Westergren (Slovenia), Ricardo Alía (Spain), Josefa Fernández-López (Spain), Luis Gil Sanchez (Spain), Pablo Gonzalez Goicoechea (Spain), Santiago C. González-Martínez (Spain), Sonia Martin Albertos (Spain), Eduardo Notivol Paino (Spain), María Arantxa Prada (Spain), Alvaro Soto de Viana (Spain), Lennart Ackzell (Sweden), Jonas Bergquist (Sweden), Sanna Black-Samuelsson (Sweden), Jonas Cedergren (Sweden), Gösta Eriksson (Sweden), Markus Bolliger (Switzerland), Felix Gugerli (Switzerland), Rolf Holderegger (Switzerland), Peter Rotach (Switzerland), Marcus Ulber (Switzerland), Sven M.G. de Vries (The Netherlands), Khouja Mohamed Larbi (Tunisia), Murat Alan (Turkey), Gaye Kandemir (Turkey), Gursel Karagöz (Turkey), Zeki Kaya (Turkey), Hasan Özer (Turkey), Hacer Semerci (Turkey), Ferit Toplu (Turkey), Mykola M. Vedmid (Ukraine), Roman T. Volosyanchuk (Ukraine), Stuart A'Hara (United Kingdom), Joan Cottrell (United Kingdom), Colin Edwards (United Kingdom), Michael Frankis (United Kingdom), Jason Hubert (United Kingdom), Karen Russell (United Kingdom), C.J.A. Samuel (United Kingdom).
 

Status of Acer opalus conservation in Europe

Genetic summary

Genetic diversity and variation  

Italian maple is sexually polymorphic and diploid, showing a high level of genetic polymorphism and high variation across Mediterranean populations (Segarra-Moragues, Gleiser, and González-Candelas, 2008). The presence of multiple genetic variants shows a healthy and adaptable species. Italian maple uses heterodichogamy, a rare reproductive system combining two types of hermaphrodites (protandrous and protogynous) and separate male individuals, which contributes to its sexual polymorphism (Gleiser et al., 2008). Random mating also occurs, which limits the risk of inbreeding (Gleiser et al., 2008). However, some populations of Italian maple have an excess of homozygotes, suggesting consistent inbreeding in those populations (Guarino and Cipriani, 2013). 

Genetic distribution and clustering  

Studies on Italian maple indicate that differentiation between populations is generally low and most sites are genetically similar (Guarino and Cipriani, 2013). Despite this overall genetic homogeneity has been observed, indicating that genetic similarity tends to decrease with geographic distance and a level of isolation by distance in populations (Guarino and Cipriani, 2013). Distinct genetic differences were found between populations in Campania and Tuscany, Italy, despite there being no clear physical barriers such as mountains or rivers between populations (Guarino and Cipriani, 2013). This suggests limited gene dispersal may be responsible for these patterns or that populations were isolated historically. 

Gene flow 

Italian maple is wind pollinated and seeds are wind dispersed. Moderate genetic differentiation among sites and the observed isolation by distance suggest that gene flow occurs across the species' range but is limited by geographic distance.


The bibliographic review was conducted by James Chaplin of the EUFORGEN Secretariat in August 2025. 

Further relevant genetic traits

NA


The bibliographic review was conducted by James Chaplin of the EUFORGEN Secretariat in August 2025. 

Genetic conservation

Threats 

Italian maple faces genetic risks from habitat fragmentation, land-use change, and isolation of populations, which can lead to reduced genetic exchange. These factors may reduce the species’ long-term adaptability and resilience. 

Management 

There is limited research on the species, which limits species-wide genetic conservation strategies for Italian maple. Conservation efforts are limited, and further research is needed to assess genetic structure, gene flow, and priority populations for in situ or ex situ conservation. Improved understanding would support more targeted and effective genetic conservation planning. 
 

The bibliographic review was conducted by James Chaplin of the EUFORGEN Secretariat in August 2025. 

Genetic Characterisation of Acer opalus and its GCUs

Availability of FRM

FOREMATIS

Further reading

Gleiser, G., Verdú, M., Segarra-Moragues, J.G., González-Martínez, S.C., and Pannell, J.R. 2008. Disassortative mating, sexual specialization, and the evolution of gender dimorphism in heterodichogamous Acer opalus. Evolution, 62(7): 1676–1688. https://doi.org/10.1111/j.1558-5646.2008.00394.x 

References

Gleiser, G., Segarra-Moragues, J.G., Pannell, J.R., and Verdú, M. 2008. Siring success and paternal effects in heterodichogamous Acer opalus. Annals of Botany, 101(7): 1017–1026. https://doi.org/10.1093/aob/mcn030 

Guarino, C. and Cipriani, G. 2013. Landscape discontinuities influence the population structure of Acer opalus ssp. obtusatum Waldst. & Kit. ex Willdenow. Plant Biosystems – An International Journal Dealing with all Aspects of Plant Biology, 147(4): 1029–1042. https://doi.org/10.1080/11263504.2013.861534 

Segarra-Moragues, J.G., Gleiser, G., and González-Candelas, F. 2008. Isolation and characterization of microsatellite loci in Acer opalus (Aceraceae), a sexually-polymorphic tree, through an enriched genomic library. Conservation Genetics, 9: 1059–1062. https://doi.org/10.1007/s10592-007-9451-7 

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