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Peter van Welzen

Prof.dr. P.C. (Peter) van Welzen, Senior researcher - Biodiversity Discovery

Contact

Email: peter.vanwelzen@naturalis.nl
Phone: +31 (0)71-751 9205
Room number: 2.03.02
“Why do tropical plants occur where they are found?”

I have a life long fascination for plants, which canalised itself to taxonomy and systematics when I started to study in the herbarium of Leiden University. Presently, I work on spurges, Euphorbiaceae, plants with small, unisexual flowers. At first sight the flowers are not impressive, but under the microscope they appear to harbour a wealth of forms, all variation on a single theme! Besides naming plants I am also curious about where they occur and how these distributions changed through time and will change due to our  land use and global warming. I like to predict the latter and see how biodiversity can best be preserved. 

Career

I graduated from Leiden University (Netherlands) with as specialities plant taxonomy, plant anatomy, and parasitological ecology (tsetse flies). The latter topic was studied in Ivory Coast. After military service I finished my PhD within four years on the species concepts, phylogeny and historical biogeography of the genus Guioa (Sapindaceae). Since then I obtained a permanent position as researcher in the, at first Rijksherbarium, later National Herbarium of the Netherlands (Leiden University). My research topics were the Sapindaceae and Euphorbiaceae for Flora Malesiana and various families for the Flora of Thailand, in combination with phylogenetic and biogeographic research. Recently, I was appointed extraordinary professor at Leiden University with the chair Tropical Plant Biogeography, sponsored by the Treub Foundation.

Research

Research interest

My main research interests are various but centered on the plants of Malesia (the countries forming the triangle between Malaysia-Philippines-Papua New Guinea) and Thailand. I revised and revise various plant families for the two flora projects, whereby my main research is formed by the spurges, the family Euphorbiaceae in Malesia, which is a large family with about 1,500 species. These species are treated genus by genus and finished genera form the basis for phylogenetic, phylogeographic and (historical) biogeographic research. Besides this taxon related research I am also interested in explaining general patterns in plant distributions and changes in those patterns, especially into the future to see how biodiversity can best be maintained. To monitor changes in biodiversity we maintain various plots in Thailand.

Keywords

Current research topics

Under construction.

Collaborations

Under construction.

Supervision PhDs

Promotor

Promotor, co-promotor, supervisor or co-supervisor of the following PhD- theses:

Ongoing PhD theses:

Chantarasuwan, B. Systematics, Phylogeny and Biogeography of Ficus subsect. Urostigma (Moraceae). Promotor.

Telford, I. Systematics, Phylogeny and Biogeography of Synostemon (Phyllanthaceae). Promotor, University of New England.

Madern, A. The rise and fall of a Miocene hotspot: palaeobiogeograpny of the early Vallesian mammals of the Vallès-Penedès (Catalunia, Spain). Promotor.

Atria, M. The Calamus javensis complex. Promotor.


Defended PhD theses:

Pruesapan, K. 2010. The rise and fall of Sauropus  (Phyllanthaceae). Promotor.

Kalkman, V.J. 2013. Studies on phylogeny and biogeography of damselflies (Odonata) with emphasis on the Argiolestidae. Promotor.

Sirichamorn, Y. 2014. Systematics and Biogeography of Aganope, Brachypterum and Derris (Fabaceae) in Asia. Promotor.

Co-promotor/supervisor

Defended PhD theses:

Buijsen, J.R.M. Phylogeny and historical biogeography of HarpulliaNephelium and Lepisanthes (Sapindaceae). Co-promotor  (discontinued).

Turner, H. 1995. Cladistics and biogeographic analyses of Arytera Blume and Mischarytera gen. nov. (Sapindaceae) with notes on methodology and a full taxonomic revision. Co-promotor.

Haegens, R.M.A.P. 2000. Taxonomy, phylogeny, and biogeography of BaccaureaDistichirhops, and Nothobaccaurea (Euphorbiaceae). Co-promotor.

Slik, J.W.F. 2001. Macaranga and Mallotus (Euphorbiaceae) as indicators of disturbance in the lowland dipterocarp forests of East Kalimantan, Indonesia. Co-promotor.

Orozco Pardo, C.I. 2001. Evolutionary biology of Brunellia Ruiz & Pavón.

Schot, A.M. 2004. Systematics of Aporosa (Euphorbiaceae). Co-promotor.

Duangjai, S. 2007. Molecular phylogenetics of Ebenaceae (Ebony family).

Sierra Daza, S.E.C. 2007. Re-shaping spurge pioneers. Circumscription, taxonomy and phylogeny of Mallotus (Euphorbiaceae s.s.). Co-promotor.

Kulju, K.K.M. 2007. Phylogenetic and taxonomic studies in MacarangaMallotus and other acalyphoid genera (Euphorbiaceae s.s.). Co-promotor.

Teaching

Courses

Under construction.

Supervision MSc Students

2015 Marcel Heijkoop
2014 Supervisor - Ottens-Treurniet, M. - Revision of Blumeodendron (Euphorbiaceae)
2014 Supervisor - Visser, M. - Phytogeographical areas in Thailand revisited: testing species distribution models
2014 Supervisor - Ende, C. van den - Explaining disjunct American - Asian distributions via dated phylogenies
2013 Supervisor - Honingh, T. - Relation altitude - speciation via endemic species in Malesia
2011 Supervisor - Frenken, M.A. - Floristic position of Java
2010 Supervisor - Arias Guerrero, S. - Taxonomy, Phylogeny and Historical Biogeography of Endospermum (Euphorbiaceae)
2009 Supervisor - Madern, A. - The current and future status of floristic provinces in Thailand

Supervision BSc Students

2016 Fabio Sweet - B.Sc. project: Which Jatropha (Euphorbiaceae) species are introduced in SE Asia and do their environmental preferences compare with those in the areas of origin
2016 Annabelle de Vries - B.Sc. project: Small surface dimples in dried leaves of Aporosa (Phyllanthaceae) explained by leaf anatomy
2014 Supervisor - Oostrum, A. van - Revision of the Malesian species of Dimorphocalyx (Euphorbiaceae)
2013 Supervisor - Kalisperi, A. - Morphological adpatations in Phyllanthaceae to obligate moth pollination.
2013 Supervisor - Driessen, T. - Relation altitude - speciation via endemic species of Borneo and New Guinea
Available student projects

Publications

2018

Journals SCI, peer-reviewed

Yu R.-Y., Welzen P.C. van 2018. A taxonomic revision of Trigonostemon (Euphorbiaceae) in Malesia. Blumea: Journal of Plant Taxonomy and Plant Geography 62: 178-229.
Go to website (DOI)

Bouman R., Welzen P.C. van, Sumail S., Echevarria G., Erskine P.D., Ent A. van der 2018. Phyllanthus rufuschaneyi: a new nickel hyperaccumulator from Sabah (Borneo Island) with potential for tropical agromining.. Botanical Studies 59: 1-12.
Go to website (DOI)

Journals non-SCI, peer-reviewed

Welzen P.C. van, Visser M., Suphunthe N., Saengrit S., Chamchumroon V. 2018. The need to protect: A comparison between three plant diversity plots in northeast Thailand. Natural History Bulletin of the Siam Society 62: 149-159.

2017

Journals SCI, peer-reviewed

Ende C. van den, White L.T., Welzen P.C. van 2017. The existence and break-up of the Antarctic land bridge as indicated by both amphi-Pacific distributions and tectonics. Gondwana Research 44: 219-227.
Go to website (DOI)

Heijkoop M., Welzen P.C. van 2017. A revision of the genus Actephila (Phyllanthaceae) in the Malesian region. Blumea: Journal of Plant Taxonomy and Plant Geography 62: 7-25.
Go to website (DOI)

Welzen P.C. van, Sweet F.S.T., Fernández-Casas F.J. 2017. A revision of Jatropha (Euphorbiaceae) in Malesia. Blumea: Journal of Plant Taxonomy and Plant Geography 62: 58-74.
Go to website (DOI)

Welzen P.C. van 2017. Reduction of Breynia subgenus Hemisauropus to B. section Cryptogynium and discussion of the B. quadrangularis complex (Phyllanthaceae). Blumea: Journal of Plant Taxonomy and Plant Geography 62: 90-91.
Go to website (DOI)

Journals non-SCI, peer-reviewed

Welzen P.C. van, Schollaardt C. 2017. How to survive as a taxonomic institute: The amalgamation of the large Dutch herbaria and their collections. 6: 163-174.

Chapters in books

Welzen P.C. van, Chayamarit K. 2017. Plumbacinaceae. Flora of Thailand 13 3: 529-537: ISBN 978-616-316-388-2.

Welzen van P.C. 2017. Sapindaceae. Flora of Peninsular Malaysia, series II: Seed Plants 6 Flora of Peninsular Malaysia, series II: Seed Plants, 6 63-191: Forest Research Institute Malaysia, Kepong. ISBN 978-967-0622-93-4.

2016

Journals SCI, peer-reviewed

Ent A. van der, Balgooy M. van, Welzen P. van 2016. Actephila alanbakeri (Phyllanthaceae): a new nickel hyperaccumulating plant species from localised ultramafic outcrops in Sabah (Malaysia). Botanical Studies 57: 6.
Go to website (DOI)

Chantarasuwan B., Rønsted N., Kjellberg F., Sungkaew S., Welzen P.C. van 2016. Palaeotropical interncontinental disjunctions revisited using a dated phylogenetic hypothesis with nearly complete species level sampling of Ficus subsect. Urostigma (Moraceae). Journal of Biogeography 43: 384-397.
Go to website (DOI)

Ottens-Treurnet M.A.D., Welzen P.C. van 2016. A revision of the Malesian genus Blumeodendron (Euphorbiaceae). Blumea: Journal of Plant Taxonomy and Plant Geography 61: 64-82.
Go to website (DOI)

Baas P., Veldkamp J.F., van Welzen P.C. 2016. On the 80th birthdays of Willem J.J.O. de Wilde and Brigitta E.E. Duyfjes. Blumea: Journal of Plant Taxonomy and Plant Geography 61: 85-86.
Go to website (DOI)

Telford I.H.R., Pruesapan K., Welzen P.C. van, Bruhl J.J. 2016. Morphological and molecular data show Synostemon trachyspermus (Phyllanthaceae, Phyllantheaea) to be a heterogeneous species assemblage. Australian Systematic Botany 29: 218–234.
Go to website (DOI)

Welzen, P.C. van 2016. Bischofia and Hymenocardia (Phyllanthaceae) in Malesia. Blumea: Journal of Plant Taxonomy and Plant Geography 61: 272-279.
Go to website (DOI)

Welzen P.C. van, Fernández-Casas F.J. 2016. Cnidoscolus (Euphorbiaceae) escaped in Malesia?. Blumea: Journal of Plant Taxonomy and Plant Geography 62: 84-86.
Go to website (DOI)

Journals non-SCI, peer-reviewed

Welzen P.C. van, Heijkoop M. 2016. Actephila saccata (Phyllanthaceae), a new species from Thailand. Thai Forest Bulletin: Botany 44: 101-103.
Go to website (DOI)

2015

Journals SCI, peer-reviewed

Chantarasuwan B., Berg C.C., Kjellberg F., Rønsted N., Garcia M., Baider C., Welzen P.C. van 2015. A new classification of Ficus Subsection Urostigma (Moraceae) based on four nuclear DNA markers (ITS, ETS, G3pdh, and ncpGS), morphology and leaf anatomy. PLOS ONE 10: e0128289.
Go to website (DOI)

Welzen P.C. van, Pruesapan K., Telford I.R.H., Bruhl J.J. 2015. Historical biogeography of Breynia (Phyllanthaceae): what caused speciation?. Journal of Biogeography 42: 1493-1502.

Telford I.R.H., Pruesapan K., Welzen P.C. van, Bruhl J.J. 2015. Molecular data consistently recover a ‘Queensland clade’ of Synostemon (Phyllanthaceae, Phyllantheae) with distinctive floral morphology. Australian Systematic Botany 27: 450-461.

van Welzen P.C. 2015. A revision of the Malesian species of Blachia (Euphorbiaceae). Blumea: Journal of Plant Taxonomy and Plant Geography 59: 163-166.

van Welzen P.C., Winkel E. 2015. A revision of Ostodes (Euphorbiaceae) in Malesia. Blumea: Journal of Plant Taxonomy and Plant Geography 59: 185-190.

van Welzen P.C., van Oostrum A.F. 2015. Revision of the Malesian species of Dimorphocalyx (Euphorbiaceae). Blumea: Journal of Plant Taxonomy and Plant Geography 59: 191-201.

Journals non-SCI, peer-reviewed

Parnell J.A.N., Pilla F., The Thai Biogeography Group (comprisingSimpson D.A., Welzen P.C. van, Chayamarit K., Chantaranothai P., Boyce P.C., Bygrave P., Byrne C., Chen S., Couch C., Curtis T., Dransfield S., Duyfjes B.E.E., Eianthong W., Esser H.J., Grote P.J., Hua Z., Jebb M.H.P., Kirkup D.W., Ke Loc P., Larsen S.S., Macklin J., Madern A., Meade C., Merklinger F., Middleton D.J., Moat J., Muasya A.M., Nakmuenwai P., Pederson H., Pendry C.A., Prajaksood A., Pooma R., Preusapan K., Puglisi C., Sathapattayanon A., Sukkharak P., Staples G., Strijk J., Suddee S., Sungkaew S., Tangjitman K., Teerwatananon A., Tovaranonte J., Ung T., Trias Blas A., Wilde W.J.J.O. de, Wilkin P., Yahara T. 2015. A re-examination of the life and work of A.F.G. Kerr and of his colleagues and friends. Thai Forest Bulletin: Botany 43: 111-131.

2014

Journals SCI, peer-reviewed

Chantarasuwan B., Baas P., Heuven B.J. van, Baider C., Welzen P.C. van 2014. Leaf anatomy of Ficus subsection Urostigma (Moraceae). Botanical Journal of the Linnean Society 175: 882-893.
Go to website (DOI)

Sirichamorn Y., Thomas D.C., Adema F.A.C.B., Welzen P.C. van 2014. Historical biogeography of Aganope, Brachypterum and Derris (Fabaceae, tribe Millettieae): insights into the origins of Palaeotropical intercontinental disjunctions and general biogeographical patterns in Southeast Asia. Journal of Biogeography 41: 882-893.
Go to website (DOI)

Welzen P.C. van, Strijk J.S., Konijnenburg-van Cittert J.H.A. van, Nucete M., Merckx V.S.F.T. 2014. Dated phylogenies of the sister genera Macaranga and Mallotus (Euphorbiaceae): Congruence in historical biogeographic patterns?. PLOS ONE 9: e85713.
Go to website (DOI)

Sirichamorn Y., Adema F.A.C.B., Roos M.C., Welzen P.C. van 2014. Molecular and morphological phylogenetic reconstruction reveals a new generic delimitation of Asian Derris (Fabaceae): Reinstatement of Solori and synonymisation of Paraderris with Derris. Taxon 63: 522-538.
Go to website (DOI)

Chantarasuwan B., Peng Y.-Q., Baas P., Rasplus J.-Y., Heuven B.J. van, Welzen P.C. van 2014. Ficus cornelisiana, a new species of Ficus subsection Urostigma (Moraceae) from the Sino-himalayan region. Blumea: Journal of Plant Taxonomy and Plant Geography 59: 6-9.
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Raes N., Cannon C.H., Hijmans R.J., Piessens T., Saw L.G., Welzen P.C. van, Slik J.W.F. 2014. Historical distribution of Sundaland’s Dipterocarp rainforests at Quaternary glacial maxima. Proceedings of the National Academy of Sciences of the United States of America 111: 16790-5.
Go to website (URI)

Welzen P.C. van, Pruesapan K., Telford I.R.H., Esser H.-J., Bruhl J.J. 2014. Phylogenetic reconstruction prompts taxonomic changes in Sauropus, Synostemon and Breynia (Phyllanthaceae tribe Phyllanteae). Blumea: Journal of Plant Taxonomy and Plant Geography 59: 77-94.

Sirichamorn Y., Adema F.A.C.B., Welzen P.C. van 2014. Derris solorioides (Fabaceae), a new limestone species with true-paniculate inflorescences from North-Central Thailand. Blumea: Journal of Plant Taxonomy and Plant Geography 59: 98-102.
Go to website (DOI)

Chapters in books

Chantarasuwan B., Ham R.W.J.M. van der, Heuven B.-J. van, Welzen P.C. van 2014. Pollen morphology of Ficus subsection Urostigma (Moraceae).

Welzen P.C. van 2014. Staphyleaceae (Flora of Thailand). 11 Flora of Thailand 4: 656-666: The Forest Herbarium, Bangkok.

2013

Journals SCI, peer-reviewed

Sirichamorn Y., Adema F.A.C.B., Welzen P.C. van 2013. (2121) Proposal to conserve the name Brachypterum against Solori (Fabaceae). Taxon 62: 179-180.

Welzen P.C. van, Gadella T.W.J., Maas P.J.M., Daly D.C., Mori S.A., Jorgensen P.M., Obermueller F.A., Kjellberg F., Ronsted N., Chantarasuwan B., Lut C.W.J. 2013. In memoriam Cees Berg (2 July 1934-31 August 2012): Obituary. Blumea: Journal of Plant Taxonomy and Plant Geography 57: 199-206.
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Stoops E., Welzen P.C. van 2013. A revision of Ptychopyxis (Euphorbiaceae) in southeast Asia. Nordic Journal of Botany 31: 94-112.
Go to website (DOI)

Raes N., Sam L.G., Welzen P.C. van, Yahara T. 2013. Legume diversity as indicator for botanical diversity on Sundaland, South East Asia. South African Journal of Botany 38: 265-272.
Go to website (URI)

Chantarasuwan B., Berg C.C., Welzen P.C. van 2013. A revision of Ficus Subsection Urostigma (Moraceae). Systematic Botany 38: 653-686.

Journals non-SCI, peer-reviewed

Beveridge N.G.P., Rauch C., Kessler P.J.A., Vugt R.R. van, Welzen P.C. van 2013. A new way to identify living species of Nepenthes (Nepenthaceae): More data needed!. Carnivorous Plant Newsletter 42: 122-128.

Parnell J.A.N., Pedersen H.A., Hodkinson T.R., Balslev H., Welzen P.C. van, Simpson D., Middleton D.J., Esser H.-J., Pooma R., Utteridge T., Staples G. 2013. Hybrids and the Flora of Thailand. Thai Forest Bulletin: Botany 41: 1-9.

Welzen P.C. van 2013. Mallotus actinoneurus and Mallotus tokiae (Euphorbiaceae), a new record and a new species for Thailand. Thai Forest Bulletin: Botany 41: 85-89.

Edited books

Welzen P.C. van, Esser H.-J., Prance G.T., Kartawinata E.K. (eds.). 2013. Flora Malesiana 1 (21): Lecythidaceae, Peraceae. Lecythidaceae, Peraceae 1 21: 140 p. National Herbarium of the Netherlands, ISBN 9789071236785.

2012

Journals SCI, peer-reviewed

Pruesapan K., Telford I.R.H., Bruhl J.J., Welzen P.C. van 2012. Phylogeny and proposed circumscription of Breynia, Sauropus and Synostemon (Phyllanthaceae), based on chloroplast and nuclear DNA sequences. Australian Systematic Botany 25: 313-330.
Go to website (DOI)

Nucete M., Konijnenburg-van Cittert J.H.A. van, Welzen P. C. van 2012. Fossils and palaeontological distributions of Macaranga and Mallotus (Euphorbiaceae). Palaeogeography, Palaeoclimatology, Palaeoecology 353: 104-115.
Go to website (DOI)

Pecnikar Z.F., Kulju K.K.J., Sierra S.E.C., Baas P., Welzen P.C. van 2012. Leaf anatomy of Mallotus and the related genera Blumeodendron and Hancea (Euphorbiaceae sensu stricto). Botanical Journal of the Linnean Society 169: 645-676.
Go to website (DOI)

Sirichamorn Y., Adema F.A.C.B., Gravendeel B., Welzen P.C. van 2012. Phylogeny of palaeotropic Derris-like taxa (Fabaceae) based on chloroplast and nuclear DNA sequences shows reorganization of (infra)generic classifications is needed. American Journal of Botany 99: 1793-1808.
Go to website (DOI)

Baas P., Roos M.C., Welzen P.C. van 2012. On Max van Balgooy's 80th birthday. Blumea: Journal of Plant Taxonomy and Plant Geography 57: 103-104.
Go to website (DOI)

Sirichamorn Y., Adema F.A.C.B., Welzen P.C. van 2012. The Genera Aganope, Derris, and Paraderris (Fabaceae, Millettieae) in Thailand. Systematic Botany 37: 404-436.
Go to website (DOI)

Journals non-SCI, peer-reviewed

Wilkin P., Suksathan P., Keeratikiat K., Welzen P.C. van, Wiland-Szymańska J. 2012. A new threatened endemic species from central and northeastern Thailand, Dracaena jayniana (Asparagaceae: tribe Nolinoideae). Kew Bulletin 67: 1-9.

Welzen P.C. van 2012. Five rare genera of Euphorbiaceae (sensu lato) in the Malay Archipelago: Alphandia, Ashtonia, Borneodendron, Cladogynos and Tapoïdes. Edinburgh Journal of Botany 69: 389-411.

Wilkin P., Suksathan P., Keeratikiat K., Welzen P.C. van, Wiland-Szymanska J. 2012. A new species from Thailand and Burma, Dracaena kaweesakii Wilkin & Suksathan (Asparagaceae subfamily Nolinoideae). PhytoKeys 26: 189-195.

2011

Journals SCI, peer-reviewed

Welzen P.C. van 2011. Revision of Dicoelia (Phyllanthaceae; Euphorbiaceae s.l.). Blumea: Journal of Plant Taxonomy and Plant Geography 56: 209-213.
Go to website (DOI)

Welzen P.C. van, Parnell J.A.N., Slik J.W.F. 2011. Wallace's Line and plant distributions: two or three phytogeographical areas and where to group Java?. Biological Journal of the Linnean Society 103: 531-545.

Journals non-SCI, peer-reviewed

Welzen P.C. van, Raes N. 2011. The floristic position of Java. Gardens’ Bulletin Singapore 63 (1&2): 329-339.

Arias Guerrero S., Welzen P.C. van 2011. Revision of Malesiana Endospermum (Euphorbiaceae) with notes on phylogeny and historical biogeography. Edinburgh Journal of Botany 68: 443-482.

Roos M.C., Berendshohn W.G., Dessein S., Hamann T., Hoffmann N., Hovenkamp P., Janssen T., Kirkup D., Kok R. de, Sierra S.E.C., Smets E., Webb C., Welzen P.C. van 2011. e-Flora Malesiana: state of the art and perspectives. Gardens’ Bulletin Singapore 63: 189-195.

Arias Guerrero S., Welzen P.C. van 2011. Revision of Malesian Endospermum (Euphorbiaceae) with notes on phylogeny and historical Biogeography. Edinburgh Journal of Botany 68: 443-483.
Go to website (DOI)

Edited books

Welzen P.C. van (eds.). 2011. Flora Malesiana 1 (20): Acoraceae, Pandaceae, Picrodendraceae. Acoraceae, Pandaceae, Picrodendraceae 1 20: 66 p. National Herbarium of the Netherlands, Leiden. ISBN 9789071236754.

Chapters in books

Welzen P.C. van, Madern P.A. , Raes N., Parnell J.A.N., Simpson D.A., Moat J, Chayamarit K., Chantaranothai P., Boyce P.C., Bygrave P., Curtis T., Dransfield S., Esser H.-J, Jebb M.H.P., Kirkup D.W., Larsen K, Larsen S.S., Macklin J., Meade C. , Middleton D.J., Muasya A.M., Nielsen I., Prajaksood A., Pendry C.A., Pooma R., Suddee S., Sungkaew S., Teerawatananon A., Trias Blasi A., Wilkin P. 2011. The Current and Future Status of Floristic Provinces in Thailand. Information Science Reference, Hershey, PA, USA. ISBN 9781609606190.

Acevedo-Rodriguez P., Welzen P.C. van, Adema F., Ham R.W.J.M. van der 2011. Sapindaceae. Springer, Heidelberg.

Welzen P.C. van 2011. Pandaceae.

Welzen P.C. van, Forster P.I. 2011. Picrodendraceae. 1 20: 45-61: Foundation Flora Malesiana, Leiden. ISBN 9789071236754.

Welzen P.C. van, Madern A., Raes N., Parnell J.A.N., Simpson D.A., Byrne C., Curtis T., Macklin J., Trias-Blasi A., Prajaksood A., Bygrave P., Dransfield S., Kirkup D.W., Moat J., Wilkin P., Couch C., Boyce P.C., Chayamarit K., Chantaranothai P., Esser H.-J., Jebb M.H.P., Larsen K., Larsen S.S., Nielsen I., Meade C., Middleton D.J., Pendry C.A., Muasya A.M., Pattharahirantricin N., Pooma R., Sudde S., Staples G.W., Sungkaew S., Teerawatananon A. 2011. The Current and Future Status of Floristic Provinces in Thailand. Information Science Reference (IGI Global), Hershey (PA).

2010

Journals SCI, peer-reviewed

Welzen P.C. van, Forster P.I. 2010. A revision of Malesian Austrobuxus (Picrodendraceae/Euphorbiaceae s.l. subfam. Oldfieldioideae). Nordic Journal of Botany 28: 189-195.
Go to website (DOI)

Barker C., Welzen P.C. van 2010. Flueggea (Euphorbiaceae s. l. or Phyllanthaceae) in Malesia. Systematic Botany 35: 541-551.

Sagun V.G., Levin G.A., Welzen P.C. van 2010. Revision and phylogeny of Acalypha (Euphorbiaceae) in Malesia. Blumea: Journal of Plant Taxonomy and Plant Geography 55: 21-60.
Go to website (DOI)

Welzen P.C. van 2010. Revision of the Asian genus Koilodepas (Euphorbiaceae). Annals of the Missouri Botanical Garden 97: 218-234.
Go to website (DOI)

Sierra S.E.C., Kulju K.K.M., Fiser Z., Aparicio M., Welzen P.C. van 2010. The phylogeny of Mallotus s.s. (Euphorbiaceae) inferred from DNA sequence and morphological data. Taxon 59: 101-116.

Welzen P.C. van, Kulju K.K.M., Sierra S.E.C., Slik J.W.F. 2010. Key to the Malesian species of Mallotus (Euphorbiaceae). Blumea: Journal of Plant Taxonomy and Plant Geography 55: 285-290.
Go to website (DOI)

Journals non-SCI, peer-reviewed

Welzen P.C. van, Pruesapan K. 2010. Four new species of Breynia (Phyllanthaceae / Euphorbia¬ceae sensu lato) and one new combination from Thailand and Malaysia. Thai Forest Bulletin: Botany 38: 111-119.

Chapters in books

Hou D., Savinov I.A., Welzen P.C. van 2010. Celastraceae.

Welzen P.C. van 2010. Leeaceae.

2009

Journals SCI, peer-reviewed

Welzen P.C. van, Kulju K.K.M., Sierra S.E.C. 2009. How to tackle revisions of large genera: lessons from Macaranga and Mallotus (Euphorbiaceae). Blumea: Journal of Plant Taxonomy and Plant Geography 54: 25-28.
Go to website (DOI)

Raes N., Welzen P. C. van 2009. The demarcation and internal division of Flora Malesiana: 1857-present. Blumea: Journal of Plant Taxonomy and Plant Geography 54: 6-8.
Go to website (DOI)

Welzen P.C., Slik J.W.F. 2009. Patterns in species richness and composition of plant families in the Malay Archipelago. Blumea: Journal of Plant Taxonomy and Plant Geography 54: 166-171.
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Journals non-SCI, peer-reviewed

Pendry C.A., Parnell J.A.N., Welzen P.C. van 2009. Biogeographical links between Thailand and Nepal and the potential for collaboration between their Flora projects. Thai Forest Bulletin: Botany 37: 169-185.

Welzen P.C. van 2009. Recent changes in Thai Euphorbiaceae sensu lato. Thai Forest Bulletin: Botany 37: 212-218.

2008

Journals SCI, peer-reviewed

Kabouw P., Welzen P.C. van, Baas P., Heuven B.J. van 2008. Styloid crystals in Claoxylon (Euphorbiaceae) and allies (Claoxylinae) with notes on leaf anatomy. Botanical Journal of the Linnean Society 156: 445-457.

Pruesapan K., Telford I.R.H., Bruhl J.J., Draisma S.G.A., Welzen P.C. van 2008. Delimitation of Sauropus (Phyllanthaceae) based on Plastid matK and Nuclear Ribosomal ITS DNA Sequence Data. Annals of Botany 102: 1007-1018.
Go to website (DOI)

Willemse L.P.M., Welzen P.C. van, Mols J.B. 2008. Standardisation in data-entry across databases: Avoiding Babylonian confusion. Taxon 57: 343-345.

Kulju K.M., Welzen P.C. van 2008. (1855) Proposal to conserve the name Mallotus against Trevia (“Trewia”) (Euphorbiaceae s.str.). Taxon 57: 1359-1360.

Chapters in books

Welzen P.C. van 2008. Sabiaceae.

Welzen P.C. van, Veldkamp J.F. 2008. Trigoniaceae. The Forest Herbarium, Bangkok.

2007

Journals SCI, peer-reviewed

Kulju K.K.M., Sierra S.E.C., Draisma S.G.A., Samuel R., Welzen P.C. van 2007. Molecular phylogeny of Macaranga, Mallotus, and related genera (Euphorbiaceae s.s.): insights from plastid and nuclear DNA sequence data. American Journal of Botany 94: 1726-1743.

Welzen P.C. van, Bulalacao L.J. 2007. The genus Alchornea (Euphorbiaceae) in the Malay Archipelago and Thailand. Systematic Botany 32: 803-818.

Kulju K.K.M., Sierra S.E.C., Welzen P.C. van 2007. Re-shaping mallotus [part 2]: Inclusion of neotrewia, octospermum and trewia in mallotus s.s. (euphorbiaceae s.s.). Blumea: Journal of Plant Taxonomy and Plant Geography 52: 115-136.

Sierra S.E.C., Aparicio M., Gebraad N.J.H., Kulju K.K.M., Welzen P.C. van 2007. The morphological range in Mallotus (Euphorbiaceae) and a taxonomic revision of its section Rottleropsis (including Axenfeldia) in Malesia, Thailand and Africa. Blumea: Journal of Plant Taxonomy and Plant Geography 52: 21-113.

Sierra S.E.C., Kulju K.K.M., Veldkamp J.F., Welzen P.C. van 2007. Resurrection of Hancea and lectotypification of Adisca (Euphorbiaceae). Blumea: Journal of Plant Taxonomy and Plant Geography 52: 361-366.

Edited books

Welzen P.C. van, Chayamarit K. (eds.). 2007. Flora of Thailand 8 (2): Euphorbiaceae (Genera G-Z). 2 Euphorbiaceae (Genera G-Z) 8: 314 p. The Forest Herbarium, Bangkok. ISBN 9789747627435.

Chapters in books

Welzen P.C. van, Sierra S.E.C, Slik J.W.F., Bollendorff S. 2007. Mallotus. 8, 2: ISBN 9789747627435.

Welzen P.C. van 2007. Euphorbiaceae of Papua. Periplus Editions, Singapore. ISBN 9780794603939.

Welzen P.C. van 2007. Sapindaceae of Papua. ISBN 9780794603939.

2006

Journals SCI, peer-reviewed

Welzen P.C. van, Sierra S.E.C., Gebraad M.J.H., Kulju K.K.M. 2006. The distinction of five Mallotus species formerly in section Hancea (Euphorbiaceae). Blumea: Journal of Plant Taxonomy and Plant Geography 51: 367-372.

Sierra S.E.C., Aparicio M., Kulju K.K.M., Fiser Z., Welzen P.C. van, Ham R.W.J.M. van der 2006. Re-shaping Mallotus [Part 1]: Expanded circumscription and revision of the genus Cordemoya (Euphorbiaceae). Blumea: Journal of Plant Taxonomy and Plant Geography 51: 519-540.

Welzen P.C. van, Sierra S.E.C. 2006. The Mallotus wrayi complex (Euphorbiaceae). Blumea: Journal of Plant Taxonomy and Plant Geography 51: 373-388.

Sierra S.E.C., Welzen P.C. van 2006. Mallotus kongkandae (Euphorbiaceae): New record for China. Blumea: Journal of Plant Taxonomy and Plant Geography 51: 365-366.

2005

Journals SCI, peer-reviewed

Kulju K.K.M., Welzen P.C. van 2005. Revision of the genus Cleidion (Euphorbiaceae) in Malesia. Blumea: Journal of Plant Taxonomy and Plant Geography 50: 197-219.

Welzen P.C. van, Sierra S.E.C. 2005. Lasiococca brevipes (Euphorbiaceae): A new combination. Blumea: Journal of Plant Taxonomy and Plant Geography 50: 275-277.

Sierra S.E.C., Welzen P.C. van, Slik J.W.F. 2005. A taxonomic revision of Mallotus section Philippinenses (former section Rottlera - Euphorbiaceae) in Malesia and Thailand. Blumea: Journal of Plant Taxonomy and Plant Geography 50: 221-248.

Sierra S.E.C., Welzen P.C. van 2005. A taxonomic revision of Mallotus section Mallotus (Euphorbiaceae) in Malesia. Blumea: Journal of Plant Taxonomy and Plant Geography 50: 249-274.

Journals non-SCI, peer-reviewed

Welzen P.C. van, Slik J.W.F., Alahuhta J. 2005. Plant distribution patterns and plate tectonics in Malesia. Biologiske Skrifter 55: 199-217.

Edited books

Chayamarit K., Welzen P.C. van (eds.). 2005. Flora of Thailand 8 (1): Euphorbiaceae (Genera A-F). 1 Euphorbiaceae (Genera A-F) 8: 303 p.

2004

Journals SCI, peer-reviewed

Welzen P.C. van, Adema F., Baas P. 2004. In Memoriam Pieter Willem Leenhouts (1926-2004). Blumea: Journal of Plant Taxonomy and Plant Geography 49: 3-10.

Sam H. van, Welzen P.C. van 2004. Revision of Annesijoa, elateriospermum and the introduced species of Hevea in Malesia (Euphorbiaceae). Blumea: Journal of Plant Taxonomy and Plant Geography 49: 425-440.

Turner H., Welzen P.C. van 2004. The Step Matrix Approach applied to SE Asian biogeography. Cladistics 20: 98-98.

Journals non-SCI, peer-reviewed

Welzen P.C. van 2004. A new combination in Meliosma (Sabiaceae). Thai Forest Bulletin: Botany 32: 168-169.

Welzen P.C. van, Phonsena P. 2004. Lepisanthes amoena (Hassk.) Leenh. (Sapindaceae), a new record for Thailand. Thai Forest Bulletin: Botany 32: 170-172.

Welzen P.C. van, Ham R.W.J.M. van der, Kulju K.K.M. 2004. Mallotus glomerulatus (Euphorbiaceae sensu stricto), a new species: description, pollen and phylogenetic position. Thai Forest Bulletin: Botany 32: 173-178.

2003

Journals SCI, peer-reviewed

Buijsen J.R.M., Welzen P.C. van, Ham R.W.J.M. van der 2003. A phylogenetic analysis of Harpullia (Sapindaceae) with notes on historical biogeography. Systematic Botany 28: 106-117.

Welzen P.C. van 2003. Revision of the Malesian and Thai species of Sauropus (Euphorbiaceae : Phyllanthoideae). Blumea: Journal of Plant Taxonomy and Plant Geography 48: 319-391.

Welzen P.C. van, Turner H., Hovenkamp P. 2003. Historical biogeography of Southeast Asia and the West Pacific, or the generality of unrooted area networks as historical biogeographic hypotheses. Journal of Biogeography 30: 181-192.

Slik J.W.F., Kessler P.J.A., Welzen P.C. van 2003. Macaranga and Mallotus species (Euphorbiaceae) as indicators for disturbance in the mixed lowland dipterocarp forest of East Kalimantan (Indonesia). Ecological Indicators 2: 311-324.

2002

Journals SCI, peer-reviewed

Sagun V.G., Welzen P.C. van 2002. Revision of the Malesian species of Micrococca (Euphorbiaceae). Blumea: Journal of Plant Taxonomy and Plant Geography 47: 149-155.

Journals non-SCI, peer-reviewed

Welzen P.C. van 2002. The correct interpretation of Euonymus auriculatus Craib (Celastraceae) and Myladenia serrata Airy Shaw (Euphorbiaceae). Natural History Bulletin of the Siam Society 50: 111-114.

2001

Journals SCI, peer-reviewed

Slik J.W.F., Welzen P.C. van 2001. A phylogeny of Mallotus (Euphorbiaceae) based on morphology: Indications for a pioneer origin of Macaranga. Systematic Botany 26: 786-796.

Turner H., Hovenkamp P., Welzen P.C. van 2001. Biogeography of Southeast Asia and the West Pacific. Journal of Biogeography 28: 217-230.

Welzen P.C. van 2001. Two new species of Sauropus (Euphorbiaceae) from Thailand, and a new combination. Blumea: Journal of Plant Taxonomy and Plant Geography 46: 499-504.

Welzen P.C. van, Turner H., Roos M.C. 2001. New guinea: A correlation between accreting areas and dispersing Sapindaceae. Cladistics 17: 242-247.

Welzen P.C., Phattarahirankanok K. 2001. Mallotus kongkandae (Euphorbiaceae), a new species from Thailand. Blumea: Journal of Plant Taxonomy and Plant Geography 46: 67-69.

Slik J.W.F., Welzen P.C. van 2001. A taxonomic revision of Mallotus sections Hancea and Stylanthus (Euphorbiaceae). Blumea: Journal of Plant Taxonomy and Plant Geography 46: 3-66.

Sevilla S., Welzen P.C. van 2001. Revision and phylogeny of Agrostistachys and Chondrostylis (Euphorbiaceae). Blumea: Journal of Plant Taxonomy and Plant Geography 46: 71-97.

Journals non-SCI, peer-reviewed

Welzen P.C. van 2001. The distichous Euphorbiaceae genera of Thailand. Thai Forest Bulletin: Botany 28: 51-58.

Welzen P.C. van, Haegens R.M.A.P., Slik J.W.F., Bollendorff S.M., Dressler S., Esser H.-J. 2001. Checklist of the genera of Thai Euphorbiaceae – I. Thai Forest Bulletin: Botany 28: 59-111.

Welzen P.C. van, Chayamarit K. 2001. Two new Mallotus and two new Sauropus species (Euphorbiaceae) endemic to Thailand. Kew Bulletin 56: 649-656.

Esser H.-J., Welzen P.C. van 2001. Colobocarpos, a new genus of South-East Asian Euphorbiaceae. Kew Bulletin 56: 657-659.

2000

Journals SCI, peer-reviewed

Bollendorff S.M., Welzen P.C. van, Slik J.W.F. 2000. A taxonomic revision of Mallotus section Polyadenii (Euphorbiaceae). Blumea: Journal of Plant Taxonomy and Plant Geography 45: 319-340.

Journals non-SCI, peer-reviewed

Slik J.W.F., Priyono, Welzen P.C. van 2000. Key to the Macaranga Thou. and Mallotus Lour. species (Euphorbiaceae) of East Kalimantan, Indonesia. Gardens’ Bulletin Singapore 52: 11-87.

1999

Journals SCI, peer-reviewed

Welzen P.C. van, Tyas K.N., Gaerlan F.J.M. 1999. The Malesian species of Melanolepis (Euphorbiaceae). Blumea: Journal of Plant Taxonomy and Plant Geography 44: 437-446.

Welzen P.C. van, Stuppy W. 1999. Phylogenetic considerations of Euphorbiaceae tribe Aleuritideae. Annals of the Missouri Botanical Garden 86: 894-903.

Forster P.I., Welzen P.C. van 1999. The Malesian species of Choriceras, Fontainea, and Petalostigma (Euphorbiaceae). Blumea: Journal of Plant Taxonomy and Plant Geography 44: 99-107.

Welzen P.C. van 1999. Revision and phylogeny of subtribes Chrozophorinae and Doryxylinae (Euphorbiaceae) in Malesia and Thailand. Blumea: Journal of Plant Taxonomy and Plant Geography 44: 411-436.

Stuppy W., Welzen P.C. van, Klinratana P., Posa M.C.T. 1999. Revision of the genera Aleurites, Reutealis and Vernicia (Euphorbiaceae). Blumea: Journal of Plant Taxonomy and Plant Geography 44: 73-98.

1998

Journals SCI, peer-reviewed

Thin N.N., Duc V.H., Welzen P.C. van 1998. A revision of the Indochinese-Malesian genus Strophioblachia (Euphorbiaceae). Blumea: Journal of Plant Taxonomy and Plant Geography 43: 479-487.

Welzen P.C. van 1998. Revisions and phylogenies of Malesian Euphorbiaceae: Subtribe Lasiococcinae (Homonoia, Lasiococca, Spathiostemon) and Clonostylis, Ricinus, and Wetria. Blumea: Journal of Plant Taxonomy and Plant Geography 43: 131-164.

Welzen P.C. van 1998. Phylogenetic versus Linnaean taxonomy, the continuing story. Taxon 47: 413-423.

Journals non-SCI, peer-reviewed

Widuri R., Welzen P.C. van 1998. A revision of the genus Cephalomappa (Euphorbiaceae) in Malesia. Reinwardtia 11: 153-184.

Kiew R., Welzen P.C. van 1998. Codiaeum variegatum var. cavernicola var. nov. (Euphorbiaceae), the second Codiaeum from Borneo. Gardens’ Bulletin Singapore 50: 31-34.

Welzen P.C. van 1998. Analytical key to the genera of Thai Euphorbiaceae. Thai Forest Bulletin: Botany 26: 1-26.

1997

Journals SCI, peer-reviewed

Welzen P.C. van 1997. Paraphyletic groups or what should a classification entail. Taxon 46: 99-103.

Esser H.J., Welzen P.C. van, Djarwaningsih T. 1997. A phylogenetic classification of the Malesian Hippomaneae (Euphorbiaceae). Systematic Botany 22: 617-628.

Repetur C.P., Welzen P.C. van, Vogel E.F. de 1997. Phylogeny and historical biogeography of the genus Bromheadia (Orchidaceae). Systematic Botany 22: 465-477.

Journals non-SCI, peer-reviewed

Welzen P.C. van 1997. Phylogenetic research: a short introduction. Rheedea 6: 11-45.

Welzen P.C. van 1997. An introduction to the Sapindaceae in Thailand. Thai Forest Bulletin: Botany 25: 21-53.

Welzen P.C. van 1997. Guioa sarcopterifructa (Sapindaceae): a new Australian species. Austrobaileya: A Journal of Plant Systematics 5: 103-105.

Welzen P.C. van, Nguyen Q.D., Chung R.C.K. 1997. A revision of the introduced species of Manihot (Euphorbiaceae) in Malesia. Rheedea 7: 77-85.

Edited books

Dransfield J., Coode M.J.E., Simpson D.A. (eds.). 1997. Plant diversity in Malesia III: Proceedings of the Third International Flora Malesiana Symposium 1995. 449 p. ISBN 1900347423.

Chapters in books

Welzen P.C. van 1997. Increased speciation in New Guinea: tectonic causes?. ISBN 1900347423.

1996

Edited books

Soepadmo E., Wong K.M., Saw L.G. (eds.). 1996. Tree Flora of Sabah and Sarawak, Volume 2. Tree Flora of Sabah and Sarawak 2 443 p. ISBN 9839592564.

Chapters in books

Balgooy M.M.J. van, Hovenkamp P.H., Welzen P.C. van 1996. Phytogeography of the Pacific - floristic and historical distribution patters in plants. SPB Academic Publishing, Amsterdam. ISBN 905103136X.

Adema F.A.C.B., Leenhouts P.W., Welzen P.C. van 1996. Sapindaceae. 2: ISBN 983959564.

1995

Journals SCI, peer-reviewed

Welzen P.C. van, Bulalacao L.J., Vanon T. 1995. A taxonomic revision of the Malesian genus Trigonopleura hook. f. (Euphorbiaceae). Blumea: Journal of Plant Taxonomy and Plant Geography 40: 363-374.

Welzen P.C. van 1995. Taxonomy and phylogeny of the Euphorbiaceae tribe Erismantheae g.l.-webster (Erismanthus, Moultonianthus, and Syndyophyllum). Blumea: Journal of Plant Taxonomy and Plant Geography 40: 375-396.

1994

Journals SCI, peer-reviewed

Welzen P.C. van 1994. Taxonomy, Phylogeny, and Geography of Neoscortechinia Hook. f. ex PAX (Euphorbiaceae). Blumea: Journal of Plant Taxonomy and Plant Geography 39: 301-320.

Jarvie J., Welzen P.C. van 1994. What are tropical floras for in SE Asia. Taxon 43: 444-448.

Journals non-SCI, peer-reviewed

Welzen P.C. van 1994. The phylogeny of Arthraxon P. Beauv. (Gramineae). Rheedea 3: 101-106.

Welzen P.C. van 1994. A taxononomic revision of S.E. Asian Chaetocarpus Thwaites (Euphorbiaceae). Rheedea 4: 93-101.

Authored books

Adema F.A.C.B., Leenhouts P.W., Welzen P.C. van 1994. Flora Malesiana 1 (11-3): Sapindaceae. Flora Malesiana 1 Flora Malesiana, ser. 1 11: 349 p. Rijksherbarium/Hortus Botanicus, ISBN 9071236218.

Edited books

Adema F., Leenhouts P.W., Welzen P.C. van (eds.). 1994. Flora Malesiana 1 (11): Part 3 (Sapindaceae). Flora Malesiana 1 11: ISBN 9071236218.

1993

Journals SCI, peer-reviewed

Welzen P.C. van, Banka R.A., Leoncito C.D. 1993. A revision of the Malesian monotypic genus Cheilosa Blume (Euphorbiaceae). Blumea: Journal of Plant Taxonomy and Plant Geography 38: 161-166.

Chapters in books

Welzen P.C. van 1993. Guioa Cav., Lepidopetalum Blume. 5: ISBN 9071236188.

1992

Journals SCI, peer-reviewed

Welzen P.C. van, Piskaut P., Windadri F.I. 1992. Lepidopetalum blume (Sapindaceae) - taxonomy, phylogeny, and historical biogeography. Blumea: Journal of Plant Taxonomy and Plant Geography 36: 439-465.

Welzen P.C. van 1992. Interpretation of historical biogeographic results. Acta Botanica Neerlandica 41: 75-87.

1991

Journals SCI, peer-reviewed

Welzen P.C. van 1991. The Malesian species of Sarcopteryx radlk. (Sapindaceae). Blumea: Journal of Plant Taxonomy and Plant Geography 36: 87-103.

Welzen P.C. van 1991. Gloeocarpus radlk. (Sapindaceae) revised. Blumea: Journal of Plant Taxonomy and Plant Geography 35: 389-392.

Journals non-SCI, peer-reviewed

Welzen P.C. van 1991. The monotypic Philippine genus Gongrospermum Radlk. (Sapindaceae). Rheedea 1: 59-61.

Chapters in books

Welzen P.C. van, Verheij E.W.M. 1991. Nephelium lappaceum L.. Pudoc, Wageningen. ISBN 9022009866.

1989

Journals SCI, peer-reviewed

Welzen P.C. van 1989. Software programs COOR and MAP. Taxon 38: 237-237.

Journals non-SCI, peer-reviewed

Welzen P.C. van 1989. Guioa Cav. (Sapindaceae): Taxonomy, Phylogeny, and Historical Biogeography. Leiden Botanical Series 12: 1-315.

Chapters in books

Welzen P.C. van, Verheij E.W.M. 1989. Nephelium lappaceum L.. Pudoc, Wageningen. ISBN 9022009858.

1988

Journals SCI, peer-reviewed

Welzen P.C. van 1988. Key to the Malesian Genera of Sapindaceae (based on vegetative and fruit characteristics). Blumea: Journal of Plant Taxonomy and Plant Geography 33: 215-237.

Welzen P.C. van 1988. Nineteen new species and a new combination in Guioa Cav. (Sapindaceae). Blumea: Journal of Plant Taxonomy and Plant Geography 33: 411-421.

Journals non-SCI, peer-reviewed

Welzen P.C. van 1988. Rectification of the position of Arthraxon microphyllus (Trin.) Hochst. var. hindustanicus (Jain & Deshpande) Almeida & Almeida. Journal of the Bombay Natural History Society 84: 268.

1985

Journals SCI, peer-reviewed

Welzen P.C. van, Hengst S. den 1985. A revision of the genus Dysolobium (Papilionaceae) and the transfer of subgenus Dolichovigna to Vigna. Blumea: Journal of Plant Taxonomy and Plant Geography 30: 363-383.

1984

Journals SCI, peer-reviewed

Welzen P.C. van, Hengst S. den 1984. The genus Mastersia (Papilionaceae, Phaseoleae). Blumea: Journal of Plant Taxonomy and Plant Geography 30: 77-87.

Welzen P.C. van, Baas P. 1984. A leaf anatomical contribution to the classification of the Linaceae complex. Blumea: Journal of Plant Taxonomy and Plant Geography 29: 453-479.

1981

Journals SCI, peer-reviewed

Welzen P.C. van 1981. A taxonomic revision of the genus Arthraxon Beauv. (Gramineae). Blumea: Journal of Plant Taxonomy and Plant Geography 27: 255-300.