![Pterocarya fraxinifolia, Ismayilli, Azerbaijan](http://www.zelkova.ch/sites/default/files/PT3-P-fraxinifolia-Ismayili--Azerbaijan.jpg)
![Pterocarya fraxinifolia, painting by Daniel Belchi](http://www.zelkova.ch/sites/default/files/Pterocarya%20fraxinifolia%20by%20Daniel%20Belchi.jpg)
Since 2015 an extension of the Project Zelkova has been elaborated in order to explore and protect other genera and families of relict trees. The main focus is put on the genus Pterocarya and on the family Juglandaceae. The genus Pterocarya has six extant species with similar disjunctions as in Zelkova. Many highly isolated populations, especially for Pterocarya fraxinifolia, are very threatened and have been never collected and/or investigated.
Leading researchers: Dr Yi-Gang Song & Sébastien Bétrisey
The project Pterocarya comprises four main objectives: (1) Ex situ conservation of Pterocarya fraxinifolia and other relict trees of the Transcaucasia. (2) In situ conservation of Pterocarya fraxinifolia with pilot restoration sites in Georgia. (3) Phylogeographic analyses of the genus Pterocarya covering the whole distribution area of Pterocarya fraxinifolia and of the whole genus Pterocarya. (4) Production of a richly illustrated and detailed booklet on the conservation status and actions needed for the whole genus Pterocarya as well as on the diversity and importance of the whole Juglandaceae family. This part, including exchange and field work in Europe, Asia and America, will be carried out by the Zelkova team of the University of Fribourg in Switzerland.
![Pterocarya fraxinifolia. Ismayilli, Great Caucasus, Azerbaijan](http://www.zelkova.ch/sites/default/files/styles/700_large/public/PT4-P-fraxinifolia-Ismayili--Azerbaijan.jpg?itok=BCuc4l9T)
![Pterocarya stenoptera. Arboretum Aubonne, Switzerland](http://www.zelkova.ch/sites/default/files/styles/700_large/public/PT10-Pterocarya-stenoptera-Aubonne.jpg?itok=tDm_4hO-)
![Pterocarya fraxinifolia. Botanic Garden Lyon, France](http://www.zelkova.ch/sites/default/files/styles/700_large/public/PT5-P-fraxinifolia-Lyon.jpg?itok=BcnWVH56)
![Pterocarya fraxinifolia. Botanic Garden Lyon, France](http://www.zelkova.ch/sites/default/files/styles/700_large/public/PT7-P-fraxinifolia-Lyon.jpg?itok=G5__VXff)
![Pterocarya stenoptera. Arboretum Aubonne, Switzerland](http://www.zelkova.ch/sites/default/files/styles/700_large/public/PT16-Pterocarya-stenoptera-Aubonne.jpg?itok=VqUt1GUH)
We are very proud to announce that Yi-Gang Song successfully completed his doctoral thesis at the University of Freiburg on the 11th December 2019. The PhD was realized in close cooperation with the Shanghai Chenshan Botanical Garden in China. On behalf of the Zelkova and Pterocarya networks we would like to congratulate him on this success. The title of the dissertation is: Past, present and future of relict trees: diversity, phylogeny, and biogeography of Juglandaceae. Yi-Gang Song is one of the most important researchers of our research and conservation network and an expert in biogeography and conservation biology of Juglandaceae and Fagaceae. Many thanks also to all colleagues who accompanied Yi-Gang on his numerous expeditions and investigations.
![Yi-Gang Song with Prof. G. Kozlowski Yi-Gang Song in China (with Prof. G. Kozlowski)](http://www.zelkova.ch/sites/default/files/styles/700_large/public/best-DSC00600-bis.gif?itok=MYI74KxE)
« Wingnuts (Pterocarya) and walnut family. Relict trees: linking the past, present and future. »
The book is the culmination of more than four years of exploration and international co-operation. The authors recount an extraordinary journey to the most beautiful and, at the same time, the most threatened relict forests. It starts by examining the last 70 or so Mya in the evolution of the Juglandaceae, presenting selected highlights of the rich paleontological history. This chapter is followed by an exhaustive presentation of the Pterocarya genus - the main subject of the book - introducing all extant species, namely P. fraxinifolia, P. stenoptera, P. tonkinensis, P. hupehensis, P. macroptera and P. rhoifolia. Detailed information on distribution, morphology, ecology and threats is provided for each species.
The second half of the book presents the nine remaining genera of the Juglandaceae: Rhoiptelea, Engelhardia, Alfaropsis, Oreomunnea, Alfaroa, Carya, Platycarya, Cyclocarya and Juglans. After a brief introduction to the global diversity, distribution and phylogeny of the Juglandaceae family, each genus is succinctly presented with details of its fossil history, morphology, ecology and distribution.
Finally, the book describes the uses as well as the most diverse and/or interesting regions of the world in terms of the highest number of Juglandaceae species (China, USA), the highest number of genera (China, Vietnam) or the most impressive or threatened members of the family (Costa Rica, Cuba).
The future of relict trees is uncertain. Many species are threatened by changes in accelerated land use and climate change. This book, which portrays the beauty and diversity of this unique family in all its glory, should encourage on-going conservation and research efforts worldwide.
![New book of the Pterocarya network New book of the Pterocarya network](http://www.zelkova.ch/sites/default/files/styles/700_large/public/buch-klein.jpg?itok=j1IAHRbW)
![Pages showing the genus Carya Pages showing the genus Carya](http://www.zelkova.ch/sites/default/files/styles/700_large/public/Carya-klein_0.jpg?itok=OBo-Se32)
![Contents of the book Contents of the book](http://www.zelkova.ch/sites/default/files/styles/700_large/public/Contents-klein.jpg?itok=Cz9IxhFR)
![Pages with Pterocarya stenoptera Pages with Pterocarya stenoptera](http://www.zelkova.ch/sites/default/files/styles/700_large/public/Pterocarya-stenoptera-klein.jpg?itok=EUcg4uG2)
The conference entitled « Relict woody plants: linking the past, present and future » took place on 19th of June 2018 in Kórnik (Poland). It was perfectly organized by the Institute of Dendrology of the Polish Academy of Sciences, and gathered researchers, conservationists and foresters from 14 countries (Poland, Switzerland, Italy, Germany, Greece, Ukraine, Lebanon, Colombia, USA, China, Georgia, Japan, Vietnam and Iran). The conference was also an occasion to celebrate internationally the new book « Wingnuts (Pterocarya) and walnut family », published by our Pterocarya network in collaboration with the Natural History Museum Fribourg (Switzerland). The event was followed by an excursion to Sudety Mountains (South Poland). The participants visited among others the Kórnik Arboretum, the Karkonosze National Park as well as the Kostrzyca Forest Gene Bank. The Zelkova-team in Fribourg would like to thank the organizers of this extraordinary meeting: Dr Anna Jasińska, Prof. Dr Adam Boratyński, Dr Monika Dering, Dr Ewa Kalemba, Radosław Rakowski, Katarzyna Sękiewicz, Dr Karolina Sobierajska, Łukasz Walas and Mikołaj Wawrzyniak, as well as the director of the Institute of Dendrology in Kórnik, Prof. Dr Jacek Oleksyn.
In October 2017, an expedition was carried out, in order to document both subspecies of Juglans jamaicensis, two of the most endangered and extraordinary members of the Juglandaceae family. While J. jamaicensis subsp. jamaicensis is still present in the Dominican Republic (more than twenty population) and in the center and east of Cuba, the species has almost completely disappeared from Puerto Rico (only one small population left known) and is under high pressure in Haiti, due to intense deforestation. The range of J. jamaicensis subsp. insularis is much smaller, the species is endemic to Cuba. It grows most exclusively in the western province Pinar del Rio. The two taxa usually come as isolated individuals or very small populations in semi-deciduous montane forest. The species often grow near streams or at the border between forested hills and cultivated lowland areas, involving high pressure from agriculture. Logging and ranching have also decreased the extension of their habitat.
With the help of local guides and forest specialists, we discovered an astonishing biodiversity and some small populations of J. jamaicensis in Viñales National Park in the west, and in the Escambray Mountains in the center of the island. Juglans jamaicensis is very scattered and needs urgent conservation action programs both in situ and ex situ.
![Viñales valley in the Province of Pinar del Rio is known worldwide for the production of the finest cigars and for its typical geological steep hills, the Mogotes. Pinar del Rio, Cuba. Viñales valley in the Province of Pinar del Rio is known worldwide for the production of the finest cigars and for its typical geological steep hills, the Mogotes. Pinar del Rio, Cuba.](http://www.zelkova.ch/sites/default/files/styles/700_large/public/1_2.jpg?itok=nsweokEx)
![The small village of Viñales is fast growing, due to its attraction for international tourists. Pinar del Rio, Cuba. The small village of Viñales is fast growing, due to its attraction for international tourists. Pinar del Rio, Cuba.](http://www.zelkova.ch/sites/default/files/styles/700_large/public/2_0.jpg?itok=s89b3aLZ)
![The typical vegetation of the Mogotes include the Cuban royal palm (Roystonea regia) and the Kapok (Ceiba pentandra), a relative of the baobab. Pinar del Rio, Cuba. The typical vegetation of the Mogotes include the Cuban royal palm (Roystonea regia) and the Kapok (Ceiba pentandra), a relative of the baobab. Pinar del Rio, Cuba.](http://www.zelkova.ch/sites/default/files/styles/700_large/public/3_1.jpg?itok=I_-8iQvd)
![Juglans jamaicensis subsp. insularis. Viñales National Park, Pinar del Rio, Cuba. Juglans jamaicensis subsp. insularis. Viñales National Park, Pinar del Rio, Cuba.](http://www.zelkova.ch/sites/default/files/styles/700_large/public/4_0.jpg?itok=tx29TbkC)
![Microcycas calocoma (CR) belongs to a monospecific genus of cycads. Only 600 individuals exist exclusively in the Province of Pinar del Rio. Viñales National Park, Pinar del Rio, Cuba. Microcycas calocoma (CR) belongs to a monospecific genus of cycads. Only 600 individuals exist exclusively in the Province of Pinar del Rio. Viñales National Park, Pinar del Rio, Cuba.](http://www.zelkova.ch/sites/default/files/styles/700_large/public/5.jpg?itok=-kDl9KYA)
![Topes de Collantes Nature Reserve Park. Sancti Spíritus, Cuba. Topes de Collantes Nature Reserve Park. Sancti Spíritus, Cuba.](http://www.zelkova.ch/sites/default/files/styles/700_large/public/6.jpg?itok=sAU88aqG)
![An old abandoned railway in Trinidad area. Sancti Spíritus, Cuba. An old abandoned railway in Trinidad area. Sancti Spíritus, Cuba.](http://www.zelkova.ch/sites/default/files/styles/700_large/public/7_0.jpg?itok=1obn1Txq)
![Juglans jamaicensis subsp. jamaicensis. Topes de Collantes Nature Reserve Park, Cienfuegos, Cuba. Juglans jamaicensis subsp. jamaicensis. Topes de Collantes Nature Reserve Park, Cienfuegos, Cuba.](http://www.zelkova.ch/sites/default/files/styles/700_large/public/8.jpg?itok=viI8mzba)
![The fruits of Juglans jamaicensis subsp. jamaicensis are eaten by rodents. Topes de Collantes Nature Reserve Park, Cienfuegos, Cuba. The fruits of Juglans jamaicensis subsp. jamaicensis are eaten by rodents. Topes de Collantes Nature Reserve Park, Cienfuegos, Cuba.](http://www.zelkova.ch/sites/default/files/styles/700_large/public/9.jpg?itok=gOW4sCdk)
![Banao Ecological Reserve suffered heavy damages after the passage of Hurricane Irma. Sancti Spíritus, Cuba. Banao Ecological Reserve suffered heavy damages after the passage of Hurricane Irma. Sancti Spíritus, Cuba.](http://www.zelkova.ch/sites/default/files/styles/700_large/public/10.jpg?itok=RnPZUDj0)
![The few tropical coastal ecosystems undamaged by touristic activities and oil exploration, hold a rare and precious flora. Varahicacos Ecological Reserve, Matanzas, Cuba. The few tropical coastal ecosystems undamaged by touristic activities and oil exploration, hold a rare and precious flora. Varahicacos Ecological Reserve, Matanzas, Cuba.](http://www.zelkova.ch/sites/default/files/styles/700_large/public/11.jpg?itok=-ae5YLtr)
![An old Chevrolet in the Streets of Havana, Cuba. An old Chevrolet in the Streets of Havana, Cuba.](http://www.zelkova.ch/sites/default/files/styles/700_large/public/13.jpg?itok=oYK-Q38a)
![Dendrocereus nudiflorus is an impressive and very rare arborescent cactus who could live for centuries. It is threaten by habitat loss. Varahicacos Ecological Reserve, Matanzas, Cuba. Dendrocereus nudiflorus is an impressive and very rare arborescent cactus who could live for centuries. It is threaten by habitat loss. Varahicacos Ecological Reserve, Matanzas, Cuba.](http://www.zelkova.ch/sites/default/files/styles/700_large/public/12.jpg?itok=E3_HLSPC)
![Live music in Viñales, Cuba. Live music in Viñales, Cuba.](http://www.zelkova.ch/sites/default/files/styles/700_large/public/14-photo.jpg?itok=qx4zWXYd)
Exploring China’s unique tree diversity
Xiaolong Mountain National Nature Reserve is located in the western part of the Qinling Mountains (Gansu province in Central China). In August 2017, an expedition took place, in order to explore the Pterocarya forests of this area. It was organized and coordinated by Yi-Gang Song, our PhD student at the University of Fribourg and at the Shanghai Chenshan Botanical Garden. The Xiaolong National Nature Reserve, characterized by the transitional climate between the warm temperate and subtropical conditions, possess a very high biodiversity and stunning variety of natural habitats. Vast virgin forests with large pure Pterocarya hupehensis stands, have been found and studied during the expedition. Additionally, two further Pterocarya species (P. macroptera and P. stenoptera) have been observed in this area, mainly along rivers. Further interesting trees, co-occurring with Pterocarya, are Juglans mandshurica, Quercus dolicholepis, Q. spinosa, Zelkova sinica and Z. schneideriana.
![Pterocarya hupehensis Pterocarya hupehensis](http://www.zelkova.ch/sites/default/files/styles/700_large/public/P-hupehensis-DSC_0346.jpg?itok=ZL-g1hW0)
![Xiaolong Mountain National Nature Reserve Xiaolong Mountain National Nature Reserve](http://www.zelkova.ch/sites/default/files/styles/700_large/public/Landscape_0.jpg?itok=3ejOaNO0)
![Forest of Pterocarya macroptera Forest of Pterocarya macroptera](http://www.zelkova.ch/sites/default/files/styles/700_large/public/P-macroptera-DSC_0373.jpg?itok=q00T3xIo)
![Lycoris sp. (Liliaceae) Lycoris sp. (Liliaceae)](http://www.zelkova.ch/sites/default/files/styles/700_large/public/Lycoris-Liliaceae_0750.jpg?itok=v4gH_BfN)
![Pterocarya hupehensis Pterocarya hupehensis](http://www.zelkova.ch/sites/default/files/styles/700_large/public/P-hupehensis.jpg?itok=wBSqmFvQ)
One of the main diversity centers of Juglandaceae
In April 2017 our Zelkova-team organized a scientific expedition to Vietnam in order to explore and collect iconographic material of Juglandaceae of this fascinating country as well as to officially sign the Memorandum of Understanding (MoU) between the University of Fribourg (Switzerland) and the Vietnam National University of Forestry (VNUF). The ceremony took place on 11th of April 2017 in Hanoi and was accompanied by a meeting with the president of VNUF Prof. Tran Van Chu, Prof. Hoàng Văn Sâm (Director of International Cooperation Division at VNUF) and Prof. Gregor Kozlowski on behalf of the University of Fribourg.
Vietnam is one of the main centers of species and genera diversity of this relict tree family, with minimum 10 species representing 6 genera: Rhoiptelea chiliantha, Alfaropsis roxburghiana, Platycarya strobilacea, Engelhardia (2 spp.), Pterocarya (2 spp.) and Carya (3 spp.). Three regions were explored: Ba Vi National Park, Cuc Phuong National Park as well as Con Dao National Park.
We would like to thank our partners at the Vietnam National University of Forestry (VNUF) in Hanoi as well as all field guides and research assistants for their help in finding populations in topographically very difficult terrain. Special thanks go to Prof. Hoàng Văn Sâm and Pham Thanh Ha (VNUF) as well as the direction of the Con Dao National Park.
![Alfaropsis roxburghiana. Botanic Garden of the VNUF Alfaropsis roxburghiana. Botanic Garden of the VNUF](http://www.zelkova.ch/sites/default/files/styles/700_large/public/Alfaropsis-roxburghiana-BG-Hanoi-MG_0671.jpg?itok=_vz78uG0)
![Prof. Hoang Van Sam, Ha Pham and Prof. Gregor Kozlowski in the Botanic Garden of VNUF Prof. Hoang Van Sam, Pham Thanh Ha and Prof. Gregor Kozlowski in the Botanic Garden of VNUF](http://www.zelkova.ch/sites/default/files/styles/700_large/public/BG-Hanoi-DSC04554.jpg?itok=y_GXkuhc)
![Bombax ceiba (Cuc Phuong National Park) Bombax ceiba (Cuc Phuong National Park)](http://www.zelkova.ch/sites/default/files/styles/700_large/public/Bombax-ceiba-Cuc-Phuong-DSC04916.jpg?itok=trbIXM6p)
![Bombax ceiba (Cuc Phuong National Park) Bombax ceiba (Cuc Phuong National Park)](http://www.zelkova.ch/sites/default/files/styles/700_large/public/Bombax-ceiba-Cuc-Phuong-MG_0951.jpg?itok=zl3gS0gm)
![Carya sinensis (Cuc Phuong National Park) Carya sinensis (Cuc Phuong National Park)](http://www.zelkova.ch/sites/default/files/styles/700_large/public/Carya-sinensis-Cuc-Phuong-DSC04980.jpg?itok=6bOMwqfb)
![Carya sinensis (Cuc Phuong National Park) Carya sinensis (Cuc Phuong National Park)](http://www.zelkova.ch/sites/default/files/styles/700_large/public/Carya-sinensis-Cuc-Phuong-MG_0861.jpg?itok=cYO7uw_m)
![Saraca dives (Cuc Phuong National Park) Saraca dives (Cuc Phuong National Park)](http://www.zelkova.ch/sites/default/files/styles/700_large/public/Cuc-Phuong-Saraca-dives-MG_0839.jpg?itok=f01FQrsr)
![Saraca dives (Cuc Phuong National Park) Saraca dives (Cuc Phuong National Park)](http://www.zelkova.ch/sites/default/files/styles/700_large/public/Saraca-dives-Cuc-Phuong-MG_0837.jpg?itok=OmBYiGZO)
![Engelhardia spicata (Con Dao National Park) Engelhardia spicata (Con Dao National Park)](http://www.zelkova.ch/sites/default/files/styles/700_large/public/Engelhardia-spicata-cf-Con-Dao-DSC05067.jpg?itok=gpNGscMk)
![Ficus auriculata (Botanic Garden of VNUF) Ficus auriculata (Botanic Garden of VNUF)](http://www.zelkova.ch/sites/default/files/styles/700_large/public/Ficus-auriculata-BG-Hanoi-DSC04627.jpg?itok=GqDiRjii)
![Ficus auriculata (Botanic Garden of VNUF) Ficus auriculata (Botanic Garden of VNUF)](http://www.zelkova.ch/sites/default/files/styles/700_large/public/Ficus-auriculata-BG-Hanoi-DSC04642.jpg?itok=5Ak0GBXj)
![Michelia aenea (Cuc Phuong National Park) Michelia aenea (Cuc Phuong National Park)](http://www.zelkova.ch/sites/default/files/styles/700_large/public/Michelia-aenea-Cuc-Phuong-MG_0876.jpg?itok=v-RXb-3s)
![Evelyne Kozlowski (Botanic Garden of VNUF) Evelyne Kozlowski (Botanic Garden of VNUF)](http://www.zelkova.ch/sites/default/files/styles/700_large/public/BG-Hanoi-DSC04626_0.jpg?itok=5uPRIUEg)
![Prof. Gregor Kozlowski with Carya sinensis (Cuc Phuong National Park) Prof. Gregor Kozlowski with Carya sinensis (Cuc Phuong National Park)](http://www.zelkova.ch/sites/default/files/styles/700_large/public/Carya-Pterospermum-GK-Cuc-Phuong-DSC04691_0.jpg?itok=tMzyA6af)
![Carya tonkinensis (Son La Province) Carya tonkinensis (Son La Province)](http://www.zelkova.ch/sites/default/files/styles/700_large/public/Carya-tonkinensis-Son-La-province-V-mDSC_5832_0.jpg?itok=235QrSnA)
![Ixora stricta (Con Dao National Park) Ixora stricta (Con Dao National Park)](http://www.zelkova.ch/sites/default/files/styles/700_large/public/Ixora-stricta-Con-Dao-_MG_1117_1.jpg?itok=xrOueF7U)
![Pterocarya tonkinensis (Pu Mat National Park) Pterocarya tonkinensis (Pu Mat National Park)](http://www.zelkova.ch/sites/default/files/styles/700_large/public/Pterocarya-tonkinensis-Pu-Mat-NP-DSC07246_0.jpg?itok=Y7ag-7DZ)
![Tacca chantieri (Cuc Phuong National Park) Tacca chantieri (Cuc Phuong National Park)](http://www.zelkova.ch/sites/default/files/styles/700_large/public/Tacca-chantieri-Cuc-Phuong-MG_0910.jpg?itok=ya16lakk)
![Prof. G. Kozlowski, Prof. H. Van Sam and Ha Pham (VNUF) Prof. G. Kozlowski, Prof. H. Van Sam and Pham Thanh Ha (VNUF)](http://www.zelkova.ch/sites/default/files/styles/700_large/public/Univ-Hanoi-DSC04548.jpg?itok=OR6uryiR)
![Pham Thanh Ha, Prof. H. Van Sam, E. Kozlowski, Prof. G. Kozlowski, Trinh Van Thanh (Botanic Garden of VNUF) Pham Thanh Ha, Prof. H. Van Sam, E. Kozlowski, Prof. G. Kozlowski, Trinh Van Thanh (Botanic Garden of VNUF)](http://www.zelkova.ch/sites/default/files/styles/700_large/public/20170411_105405%5B1%5D_0.jpg?itok=qvWHBygg)
A high diversity of Carya species across the East Coast
The genus Carya is quite common in temperate forests of the northeastern United States and also in the vicinity of swamp forests throughout the southeastern states. Our journey began in South Carolina, with the exploration of the Congaree National Park, one of the most important old growth bottomland hardwood forests still existing in the country. These complex ecosystems are seasonally flooded and represent a unique habitat for singular trees such as the bald cypress (Taxodium distichum) and the water tupelo (Nyssa aquatica). Our goal was to take pictures and gain knowledge and information on natural stands of water hickory (Carya aquatica) and nutmeg hickory (Carya myristiciformis), which are often present in less flooded parts of this type of forest.
For the second part of our expedition, we benefited from close partnerships with the Arnold Arboretum of the Harvard University, which holds probably the most comprehensive ex-situ collection of the genus Carya in the world. Thanks to the help of Michael S. Dosmann, curator of the living collections, we were able to visit and document a part of this extraordinary collection. We then visited some natural stands of Carya (C. ovata, C. glabra and C. cordiformis) in the Blue Hills Reservation with the help of Irina Kadis and Kathryn Richardson from the Arnold Arboretum, who organized our expedition.
![Fruits of Carya ovata, Arnold Arboretum Fruits of Carya ovata, Arnold Arboretum](http://www.zelkova.ch/sites/default/files/styles/700_large/public/USA_9-p.jpg?itok=BUWkKxK8)
![Carya myristiciformis, a very rare species, growing along Guilliard Lake, Francis Marion National Forest, South Carolina Carya myristiciformis, a very rare species, growing along Guilliard Lake, Francis Marion National Forest, South Carolina](http://www.zelkova.ch/sites/default/files/styles/700_large/public/USA_2-p.jpg?itok=5-IaY6jd)
![Carya aquatica in the vicinity of a flooded forest, Lee State Park, South Carolina Carya aquatica in the vicinity of a flooded forest, Lee State Park, South Carolina](http://www.zelkova.ch/sites/default/files/styles/700_large/public/USA_3-p.jpg?itok=cdf2WnyN)
![Fruits of Carya aquatica, Lee State Park, South Carolina Fruits of Carya aquatica, Lee State Park, South Carolina](http://www.zelkova.ch/sites/default/files/styles/700_large/public/USA_4-p.jpg?itok=KXO5KY2h)
![Tilandsia usneoides, a Bromeliaceae emblematic of the southern States Tilandsia usneoides, a Bromeliaceae emblematic of the southern States](http://www.zelkova.ch/sites/default/files/styles/700_large/public/USA_5-p.jpg?itok=QOZh3sQM)
![Blue Hills Reservation, Massachussetts Blue Hills Reservation, Massachussetts](http://www.zelkova.ch/sites/default/files/styles/700_large/public/USA_6-p.jpg?itok=Cc0nnHYp)
![Irina Kadis, Arnold Arboretum, and Sébastien Bétrisey in front of a Carya ovata stand in the Blue Hills Reservation Irina Kadis, Arnold Arboretum, and Sébastien Bétrisey in front of a Carya ovata stand in the Blue Hills Reservation](http://www.zelkova.ch/sites/default/files/styles/700_large/public/USA_7-p.jpg?itok=0d9znG2Y)
![Fruits of Carya cordiformis, Arnold Arboretum Fruits of Carya cordiformis, Arnold Arboretum](http://www.zelkova.ch/sites/default/files/styles/700_large/public/USA_10-p.jpg?itok=br3enADm)
![Carya glabra and Carya cordiformis stand Carya glabra and Carya cordiformis stand](http://www.zelkova.ch/sites/default/files/styles/700_large/public/USA_8-p.jpg?itok=3iB0erbr)
![Peatbog with Chamaecyparis thyoides, Blue Hills Reservation Peatbog with Chamaecyparis thyoides, Blue Hills Reservation](http://www.zelkova.ch/sites/default/files/styles/700_large/public/USA_11-p.jpg?itok=3VF9QFtP)
Understanding the ecology of a species requires expeditions to its country of origin and visiting its wild populations. However, field explorations are often cost- and time-consuming, especially when lacking a solid background on the species that we want to study. The Royal Botanic Garden in Edinburgh offers a unique alternative and allows studying different species of the genus Pterocarya found in its ex-situ collections. In 2016 we have visited the garden twice and been able to observe the most important criteria of differentiation between the species (especially terminal buds, leaflet and nuts) and bring back numerous pictures and knowledge, which will be very helpful for future expeditions in wild populations of Pterocarya in Asia. We would like to thank warmly Peter Brownless of the Royal Botanic Garden of Edinburgh for his precious help and advice.
![Pterocarya macroptera var. macroptera, Royal Botanic Garden Edinburgh Pterocarya macroptera var. macroptera, Royal Botanic Garden Edinburgh](http://www.zelkova.ch/sites/default/files/styles/700_large/public/SCO_1.jpg?itok=Crx1RS96)
![Pterocarya macroptera var. macroptera, with caducous bud scales on terminal buds, Royal Botanic Garden Edinburgh Pterocarya macroptera var. macroptera, with caducous bud scales on terminal buds, Royal Botanic Garden Edinburgh](http://www.zelkova.ch/sites/default/files/styles/700_large/public/SCO_2.jpg?itok=b75q_F7S)
![Pterocarya macroptera var. delavayi with caducous bud scales, Royal Botanic Garden Edinburgh Pterocarya macroptera var. delavayi with caducous bud scales, Royal Botanic Garden Edinburgh](http://www.zelkova.ch/sites/default/files/styles/700_large/public/SCO_4.jpg?itok=FIZwcWsI)
![Pterocarya rhoifolia, Royal Botanic Garden Edinburgh Pterocarya rhoifolia, Royal Botanic Garden Edinburgh](http://www.zelkova.ch/sites/default/files/styles/700_large/public/SCO_5.jpg?itok=UABmzsin)
![Flowers of Pterocarya rhoifolia, Royal Botanic Garden Edinburgh Flowers of Pterocarya rhoifolia, Royal Botanic Garden Edinburgh](http://www.zelkova.ch/sites/default/files/styles/700_large/public/SCO_6.jpg?itok=cVt86Jvv)
![Fruits of Pterocarya rhoifolia, Royal Botanic Garden Edinburgh Fruits of Pterocarya rhoifolia, Royal Botanic Garden Edinburgh](http://www.zelkova.ch/sites/default/files/styles/700_large/public/SCO_7_0.jpg?itok=HNDq6Jnh)
![Pterocarya x rehderiana, a hybrid between P. fraxinifolia and P. stenoptera Pterocarya x rehderiana, a hybrid between P. fraxinifolia and P. stenoptera](http://www.zelkova.ch/sites/default/files/styles/700_large/public/SCO_8.jpg?itok=yGy9K-1L)
![The Tropical Palm House was built in 1834 and is the oldest of the Royal Botanic Garden Edinburgh The Tropical Palm House was built in 1834 and is the oldest of the Royal Botanic Garden Edinburgh](http://www.zelkova.ch/sites/default/files/styles/700_large/public/Edinburgh.jpg?itok=6C-rxh1n)
In April 2016 our Zelkova-team organized a scientific expedition to Costa Rica in order to explore and collect iconographic material of poorly documented Juglandaceae of Neotropis. Costa Rica is a center of species diversity for two genera of this family: Alfaroa (minimum 4 species) and Oreomunnea (2 species). They are typical elements of mountain forests and are growing often together with some other trees belonging to temperate families and genera (e.g., Quercus, Alnus, etc.).
We would like to thank all field guides and research assistance for their help in finding populations in topographically very difficult terrain. Special thanks go to Bryan Finegan, Leonel Coto and Diego Delgado (CATIE, Turrialba) for finding Alfaroa manningii and Oreomunnea mexicana as well as to Erick Viquez for A. williamsii and A. costaricensis.
![Basiliscus plumifrons Basiliscus plumifrons](http://www.zelkova.ch/sites/default/files/styles/700_large/public/Basiliscus-plumifrons2-Tortuguero-NP-small_0.jpg?itok=UztwPPrw)
![Young leaves of Oreomunnea mexicana Young leaves of Oreomunnea mexicana](http://www.zelkova.ch/sites/default/files/styles/700_large/public/DSC01650-Young-Oreomunnea-mexicana-small_0.jpg?itok=NSap7LMM)
![Forest with Oreomunnea mexicana, Tapanti NP Forest with Oreomunnea mexicana, Tapanti NP](http://www.zelkova.ch/sites/default/files/styles/700_large/public/DSC01665-Tapanti-Oreomunnea-forest-small_0.jpg?itok=TFVpJx28)
![Leonel Coto (CATIE) in front of Oreomunnea mexicana Leonel Coto (CATIE) in front of Oreomunnea mexicana](http://www.zelkova.ch/sites/default/files/styles/700_large/public/DSC01732-Diego-Delgado-Catie-Turrialba-small_0.jpg?itok=GTrGloj1)
![Iguana iguana Iguana iguana](http://www.zelkova.ch/sites/default/files/styles/700_large/public/Iguana-iguana-Tortuguero-NP-small.jpg?itok=K7PH05wW)
![Young shoots of Oreomunnea mexicana Young shoots of Oreomunnea mexicana](http://www.zelkova.ch/sites/default/files/styles/700_large/public/IMG_5260-Oreomunnea-mexicana-small.jpg?itok=lsQfEu8t)
![Leaves of Oreomunnea mexicana Leaves of Oreomunnea mexicana](http://www.zelkova.ch/sites/default/files/styles/700_large/public/IMG_5272-Oreomunnea-mexicana-small.jpg?itok=cviDLwxd)
![Seedling of Oreomunnea mexicana Seedling of Oreomunnea mexicana](http://www.zelkova.ch/sites/default/files/styles/700_large/public/IMG_5316-Seedling-Oreomunnea-mexicana-small.jpg?itok=rwGH_Dsu)
![Typical "ears" on a leaflet basis of Oreomunnea mexicana Typical "ears" on a leaflet basis of Oreomunnea mexicana](http://www.zelkova.ch/sites/default/files/styles/700_large/public/IMG_5338-Oreomunnea-mexicana-small.jpg?itok=x5E0Zbq8)
![Large leaves of Alfaroa manningii Large leaves of Alfaroa manningii](http://www.zelkova.ch/sites/default/files/styles/700_large/public/IMG_5671-Alfaroa-manninghi-small.jpg?itok=aJbq5IWl)
![Fruits of Alfaroa williamsii (pictures: Erick Viquez) in Juan Castro Blanco NP Fruits of Alfaroa williamsii (pictures: Erick Viquez) in Juan Castro Blanco NP](http://www.zelkova.ch/sites/default/files/styles/700_large/public/P1020373-Alfaroa-williamsii-E-Viquez-Juan-Castro-Blanco-NP-small_0.jpg?itok=a8o-Fnkg)
![Ramphastos sulfuratus Ramphastos sulfuratus](http://www.zelkova.ch/sites/default/files/styles/700_large/public/Ramphastos-sulfuratus-Tortuguero-NP-small.jpg?itok=UWNGkzBm)
![Red eyed tree frog Red eyed tree frog](http://www.zelkova.ch/sites/default/files/styles/700_large/public/Red%20eyed%20Tree%20frog%20Corcovado%20NP.jpg?itok=1f3SpPQ7)