Photo: Leanne Dreyer

© 2016 biological interactions

Department of Botany and Zoology


biological interactions

Prof. Leanne Dreyer

After obtaining a M.Sc. (Botany) degree at the University of Stellenbosch, I started working as scientist in the National Herbarium, SANBI, Pretoria. During this time, I also enrolled for a PhD degree in Plant Systematics at the University of Pretoria. While working on my PhD, I was sent to Kew Gardens in London where I acted as the South African Botanical Liaison Officer. Shortly after completion of my PhD I resigned from SANBI, and initiated a Postdoctoral Fellowship under the mentorship of Prof Peter Linder at the University of Cape Town. I was employed as lecturer in plant systematics at Stellenbosch University upon completion of this postdoc, and have been here ever since.

I am a plant systematist, and love working at the interface between systematics and ecology. I have a strong background in morphology, karyology, palynology and molecular systematics, and believe in a multidisciplinary approach to unravelling scientific complexity.

I have two major research interests, namely (1) gaining insight into the systematics and ecology of the massive GCFR genus Oxalis and (2) inter-organismal interactions, specifically the complex relations between Protea-infructescences, ophiostomatoid fungi and the arthropod and other vectors involved in this intricate and complex system.


Oxalis biosystematics

Recalcitrant Oxalis seedlings display unusual seedling germination strategies, and this appears to be coupled with complex physiological and endosymbiotic associations. So a major aim in our Oxalis research for the next couple of years will be to gain insight into this system. In addition, preliminary results from next generation sequencing of representatives of southern African Oxalis has brought important insights into the disparities between chloroplast and ITS data, has resolved the base of the Oxalis phylogeny with increased support, and strongly suggests that hybridization may have shaped the radiation of this lineage in the GCFR. We aim to explore all of these aspects in much more detail, with Dr Rosi Smickle (Charles University) driving most of this work in conjunction with Dr Kenneth Oberlander. The third Oxalis related research focus will centre on the diversity, ecology and reproductive implications of the association between certain Oxalis species and the anther smut fungal genus Thecaphora.

Plant-animal-fungal interactions

Most of the current research on the association between ophiostomatoid fungi and Protea infructescences is molecular in nature. The genomes of two Knoxdaviesia species have been sequenced, and we are now using insights gained from this to understand the genetic control of systems such as mating types and substrate utilization of these fungi. Although numerous studies have now focused on the population genetics of Knoxdaviesia, the population genetics of the Ophiostoma species in this system remain largely unexplored. A population genetic analysis of O. splendens (and relatives) is ongoing, and more such studies will follow. There are still many ecological questions to address in this system, and two PhD studies will focus on diverse ecological aspects in 2016.

Current Research

Post-doctoral fellows:

Kenneth Oberlander

One of the leading researchers in our Oxalis team, specializing in molecular phylogenetics.


PhD students:

Oxalis biosystematics

Michelle Jooste

Michelle is starting her M.Sc. studies in 2016. She will explore the unusual seedling germination strategy in Oxalis, and attempt to relate this to physiological adaptations and diverse endophytic associations. She will be supervised by myself, Prof Guy Midgley and Dr Kenneth Oberlander


Plant-animal-fungal interactions

Janneke Aylward

Janneke is exploring the reproductive biology and genomics of ophiostomatoid fungi associated with Protea plants. She forms part of the DST-NRF Centre of Excellence in Tree Health Biotechnology (CTHB) and is co-supervised by Dr. Francois Roets (Stellenbosch University) and Profs. Emma Steenkamp, Brenda Wingfield and Michael Wingfield at the University of Pretoria.


Natalie Theron-De Bruin

Natalie is in her final year of study, exploring the diverse systematic, ecological and functional associations between ophiostomatoid fungi, Protea hosts and arthropod, specifically focusing on mites in this system. Her main supervisor is Dr Francois Roets, while I act as co-supervisor.


Vuyo Mukwevo

Vuyo is starting his PhD in 2016, and will explore detailed ecological aspects of the ophiostomatoid fung-Protea-arthropod-bird interactions within the GCFR. Dr Francois Roets will be his main supervisor, while I will act as co-supervisor.


M.Sc. students:

Nombuso Ngubane

Nombuso is in her second year of study, exploring the genetic diversity complex of the Ophiostoma splendens complex across the GCFR, and the genetic diversity of members of the O. splendens clade in northern Protea species. Her studies are supervised by myself and Dr Francois Roets.

Post-docs & Students

Contact me directly:



1. Roets, F., De Beer, Z.W., Dreyer, L.L., Crous, P.W., Zipfel, R. & Wingfield, M.J.  2006. Multigene phylogeny for Ophiostoma spp. reveals two new species from Protea infructescences. Studies in Mycology 55: 199-212 (IF = 5.923)

2. Roets, F., Wingfield, M.J., Dreyer, L.L., Crous, P.W., & Bellstedt, D.U. 2006.  A PCR-based method to detect species of Gondwanamyces and Ophiostoma on surfaces of insects colonizing Protea flowers. Canadian Journal of Botany 84:  989-994 (IF = 1.19)


1. Roets, F., Wingfield, M.J., Crous, P.W. & Dreyer, L.L. 2007. Discovery of fungus-mite-mutualism in an unique niche.  Environmental Entomology 36: 1226-1237. (IF = 1.467)


1. Bellstedt, D.U., Van Zyl, L., Marais, E.M. & Dreyer, L.L. 2008. Phylogenetic relationships, character evolution and biogeography of southern African members of Zygophyllum (Zygophyllaceae) based on based on three plastid regions. Molecular Phylogenetics and Evolution 47:  932-949 (IF = 3.871)

2. Roets, F., De Beer, W., Crous, P.W., Dreyer, L.L. & Wingfield, M.J. 2008. Ophiostoma gemellus and Sporothrix variecibatus from mites infesting Protea infructescences in South Africa. Mycologia 100: 496-510. (IF = 1.56)

3. Roets, F., Dreyer, L.L., Wingfield, M.J. & Begeroc, D.  2008. Thecaphora capensis sp. nov., an unusual new anther smut on Oxalis in South Africa. Persoonia 21: 147-152 (IF = 1.364)

4. Zietsman, J., Dreyer, L.L. & Esler, K.J. 2008. Reproductive biology and ecology of selected rare and endangered Oxalis L. (Oxalidaceae) plant species. Biological Conservation 141: 1475-1483 (IF = 3.566)


1. Curran, H., Roets, F. & Dreyer, L.L. 2009. Anther-smut fungal infection of South African Oxalis species: spatial distribution patterns and impacts on host fecundity. South African Journal of Botany; Pollination Special Issue. 75: 807–815 (IF = 1.106)

2. Oberlander, K.C., Emshwiller, E., Bellstedt, D.U. & Dreyer, L.L. 2009. A model of bulb evolution in the eudicot genus Oxalis L.  Molecular Phylogenetics and Evolution Special Cape Biota Issue 51: 54–63 (IF = 3.889)

3. Roets F., Dreyer, L.L., Crous, P.W., Wingfield, M.J. 2009. Mite-mediated hyperphoretic dispersal of Ophiostoma spp. from the infructescences of South African Protea spp. Environmental Entomology 38(1):  143–152 (IF = 1.534)

4. Roets, F., Wingfield, M.J., Crous, P.W. & Dreyer, L.L. 2009. Fungal radiation in the Cape Floristic Region: an analysis based on Gondwanamyces and Ophiostoma. Molecular Phylogenetics and Evolution Special Cape Biota Issue 51: 111–119 (IF = 3.889)

5. Verboom, G. A., Dreyer L. L. & Savolainen, V. 2009. Understanding the origins and evolution of the world’s biodiversity hotspots: the biota of the African ‘Cape Floristic Region’ as a case study. Molecular Phylogenetics and Evolution Special Cape Biota Issue 51: 1–4 (IF = 3.889)

6. Verboom, G.A., Archibald, J.K. Bakker, F.T., Bellstedt, D.U., Conrad, F., Dreyer, L.L., Forest, F., Galley, C., Goldblatt, P., Henning, J.F.,  Mummenhoff, K., Linder, H.P., Muasya, A. M., Oberlander, K.C., Savolainen, V., Snijman, D.A., Van der Niet, T. & Nowell, T.L.  2009. Origin and diversification of the Greater Cape flora: ancient species repository, hot-bed of recent radiation, or both? Molecular Phylogenetics and Evolution Special Cape Biota Issue 51: 44–53 (IF = 3.889)

7. Zietsman, J., Dreyer, L.L. & Jansen van Vuuren, B. 2009. Phylogeographic patterns in Oxalis (Oxalidaceae): a tale of rarity, recent divergence and a widespread congener in the Cape Floristic Region. South African Journal of Botany 75: 27–33 (IF = 1.106)


1. Albert, B., Nadot, S., Dreyer L.L. & Ressayre, A. 2010. The influence of tetrad shape and intersporal callose wall formation on pollen aperture pattern ontogeny in two unrelated eudicot species. Annals of Botany 106: 557–564 (IF = 4.03)

2. Oberlander, K.C., Dreyer, L.L. & Roets, F. 2010.  New primers for single-copy nuclear-encoded chloroplast-expressed glutamine synthetase (ncpGS) in Oxalidaceae. American Journal of Botany 97(12): E146-E148 (IF = 2.663)

3. Roets, F., Wingfield, B.D., De Beer, Z.W., Wingfield, M.J, & Dreyer, L.L. 2010. Two new Ophiostoma species from Protea caffra in Zambia. Persoonia 24: 18-28 (IF = 1.364)


1. De Jager, M.L., Ellis, A.G. & Dreyer, L.L. 2011. Do pollinators influence the assembly of flower colours within plant communities? Oecologia 442: 543-553. (IF = 3.011)

2. Oberlander, K.C., Dreyer, L.L. & Bellstedt, D.U.  2011. Phylogenetics of southern African Oxalis: taxon- vs character-rich data sets converge on structure. Taxon 60: 1667-1677 (IF = 2.782)

3. Roets, F., Wingfield, B.D., Wingfield, M.J. & Dreyer, L.L. 2011. Mites are the most common vectors of the fungus Gondwanamyces proteae in Protea infructescences. Fungal Biology 115: 343–350 (IF = 2.082)

4. Warren, B.H., Bakker, F.T., Bellstedt, D.U., Bytebier, B., Claßen-Bockhoff, R., Dreyer, L.L., Edwards, D., Forest, F., Galley, C., Hardy, C.R., Linder, H.P., Muasya, M.A., Mummenhoff, K., Oberlander, K.C., Quint, M., Richardson, J.E., Savolainen, V., Schrire, B.D., Van der Niet, T., Verboom, G.A., Yesson, C. & Hawkins, J.A. 2011. Consistent phenological shifts in the making of a biodiversity hotspot: the Cape flora. BMC Evolutionary Biology 11: 1471-2148 (IF = 3.285)


1. Turketti, S.S., Dreyer, L.L. & Esler, K.J. 2012. Three-dimensional reciprocity in Oxalis. South African Journal of Botany 78: 195–202 (IF = 1.34)

2. Roets F., Theron, N, Wingfield M.J. and Dreyer L.L. 2012. Biotic and abiotic constraints facilitate host-exclusivity of ophiostomatoid fungi on Protea. Fungal Biology 116: 49–61 (IF = 2.139)

3. Oberlander, K.C., Roets, F. & Dreyer, L.L. 2012. Chloroplast phylogeography of threatened aquatic Oxalis (Oxalidaceae): significant inter-population structure, divergent haplotypes and conservation implications. Conservation Genetics 13: 789–799 (IF = 2.183)

4. Theron, N., Roets, F., Dreyer, L.L., Esler, K.J. & Euckerman, E. 2012. Description of new genus and eight new species of Tydeidoidae (Acari: Prostigmata, Actinedida) from Protea species in South Africa. International Journal of Acarology 38: 257–273 (IF = 0.569)

5. Crous, P.W., Summerell, B.A., Shivas, R.G., Burgess, T.I., Decock, C.A., Dreyer, L.L., Granke, L.L., Guest, D.I., Hardy, G.E.St.J., Hausbeck, M.K., Hüberli, D., Jung, T., Koukol, O., Lennox, C.L., Liew, E.C.Y., Lombard, L., McTaggart, A.R., Pryke, J.S., Roets, F., Saude, C., Shuttleworth, L.A., Stukely, M.J.C., Vanky, K., Webster, B.J., Windstam, S.T., Groenewald, J.Z.. 2012. Fungal Planet description sheets: 107-127. Persoonia 26: 138-182 (IF = 3.486) – 3/24 Mycology, top 20%

6. Curran, H.R., Dreyer, L.L. & Roets, F. 2012. Impact of disease frequency and host density on pollination and transmission of an African anther-smut fungus. Planta 236:1677-1685  (IF = 3.376)

7. Roets, F., Curran, H.R. & Dreyer, L. 2012.  Morphological and reproductive consequences of an anther-smut fungus on Oxalis. Sydowia 64: 267-280 (IF = 0.681)


1. Krejčíková, J., Sudová, R., Oberlander, K.C., Dreyer, L.L. & Suda, J. 2013. The ploidy enigma of Oxalis pes-caprae: where do the invasive pentaploids come from? Biological invasions 15: 1189-1194  (IF = 2.509)

2. Roets, F., Oberlander, K.C. & Dreyer, L.L. 2013. Two new Oxalis species from the Ai-Ais / Richtersveld Transfrontier Park, South Africa. Blumea 57: 229-235 (IF = 0.375)

3. Krejčíková, J., Sudová, R., Lučanová, M., Trávníček, P., Urfus, T., Vít, P., Schneeweiss, H., Kolano, B., Oberlander, K., Dreyer, L., & Suda, J. 2013. High ploidy diversity and distinct patterns of cytotype distribution in a widespread species of Oxalis in the Greater Cape Floristic Region. Annals of Botany 111: 641–649

4. Krejčíková, J., Sudová, R., Oberlander, K.C., Dreyer, L.L. & Suda, J. 2013. The spatio-ecological segregation of different cytotypes of Oxalis obtusa (Oxalidaceae) in contact zones. South African Journal of Botany 88: 62–68 (IF = 1.34)

5. Dreyer, L.L., Oberlander, K.C. & Roets, F. 2013. Two new Oxalis (Oxalidaceae) species from the Richtersveld National Park, South Africa. Phytotaxa 89: 53–63 (IF = 1.376)

6. Suda, J., Oberlander, L.L. & Dreyer, L.L. 2013. Two new species of Oxalis (Oxalidaceae) from the Greater Cape Floristic Region. Phytotaxa 124: 13–24. (IF = 1.376)

7. Haukka, A.K., Esler, K.J. & Dreyer, L.L. 2013. Effects of soil type and climate on growth and flowering phenology of weedy and non-weedy plants – a case study on three Oxalis species. South African Journal of Botany 88: 152–163. (IF = 1.34)


1. Aylward, J., Dreyer, L.L., Steenkamp, E.T., Wingfield, M.J. & Roets, F. 2014. Development of polymorphic microsatellite markers for the genetic characterisation of Knoxdavesia proteae (Ascomycota: Microascales) using ISSR-PCR and pyrosequencing. Mycological Progress 13: 439–444 (IF = 1.543)

2. Magadlela, A., Kleinert, A., Dreyer, L.L. & Valentine, A.J. 2014. Phosphorus deficiency affects N nutrition of two legume tree species from the Fynbos Mediterranean ecosystem. Australian Journal of Botany 62: 1-9. DOI: 10.1071/BT13264  (IF = 0.9)

3. Oberlander, K.C., Roets, F. & Dreyer, L.L.  2014. Pre-Pleistocene origin of an endangered habitat: links between vernal pools and aquatic Oxalis in the Cape Floristic Region of South Africa. Journal of Biogeography 41(8): 1572–1582 (IF = 4.544)

4. Machingambi, N.M., Roux, J., Dreyer, L.L. & Roets, F. 2014. Bark and ambrosia beetles (Curculionidae: Scolytinae), their phoretic mites (Acari) and associated Geosmithia species (Ascomycota: Hypocreales) from Virgilia trees in South Africa. Fungal Biology 118: 472-483. (IF = 2.139)

5. Dreyer, L.L., MacFarlane, R., Roets, F. & Oberlander. 2014. An unusual night flowering Oxalis from South Africa. Systematic Botany 39(4): 1154-1160.

6. Aylward, J., Dreyer, L.L., Steenkamp, E., Wingfield, M.J. & Roets, F. 2014. Panmixia defines the genetic diversity of a unique arthropod-dispersed fungus specific to Protea flowers.  Ecology and Evolution 4(17): 3444–3455. doi: 10.1002/ece3.1149 (IF = 1.658)

7. Oberlander, K.C., Roets, F. & Dreyer, L.L. 2014. Discovery of substantial Oxalis diversity and endemism in a desert biodiversity hotspot. Phytotaxa 181: 79-95. (IF = 1.797)

8. Roets, F., Oberlander, K.C. & Dreyer L.L. 2014. New relatives of Oxalis pes-caprae L. (Oxalidaceae) from South Africa. Blumea 59: 131-138. (IF = 0.375)


1. Machingambi, N.E., Dreyer, L.L., Oberlander, K.C., Roux, J. & Roets, F. 2015. Death of endemic Virgilia oroboides trees in South African national caused by Diaporthe virgiliae sp. nov. Plant Pathology 64: 1149-1156. DOI: 10.1111/ppa.12341 (IF = 2.97)

2. Aylward, J., Dreyer, L.L., Steenkamp, E.M., Wingfield, M.J., Roets, F. 2015. Long-distance dispersal and recolonization of a fire-destroyed niche by a mite-associated fungus. Fungal Biology 119: 245-256. DOI: 10.1016/j.funbio.2014.12.010  (IF = 2.139)

3. Magadlela A, Vardien W, Kleinert A, Dreyer L, Valentine AJ. 2015. Does phosphorus deficiency affect nodule bacterial composition and N-nutrition of legume tree species, Virgilia divaricata in the Cape Fynbos ecosystem?  Australian Journal of Botany 63: 379-386. DOI:  (IF = 0.9)

4. Musvuugwa, T., de Beer, Z.W., Duong, T.A., Dreyer, L.L., Oberlander, K.C. & Roets, F. 2015. New species of Ophiostomatales from Scolytinae and Platypodinae beetles in the Cape Floristic Region, including the discovery of the sexual state of Raffaelea. Antonie van Leeuwenhoek Journal of Microbiology 108:933-50. DOI 10.1007/s10482-015-0547-7 (IF = 1.81)

5. Van der Colff, D. Dreyer, L.L., Valentine, A.J. & Roets, F. 2015. Invasive plant species may serve as biological corridor for the invertebrate fauna of naturally isolated hosts. Journal of Insect Conservation 19:863–875. DOI 10.100741-015-9804-3. (IF = 1.72)

6. Aylward, J. Dreyer, L.L., Steenkamp, E., Wingfield, M.J. & Roets, F. 2015. Knoxdaviesia proteae is not the only Knoxdaviesia-symbiont of Protea repens. IMA Fungus 6(2): 471–476;  doi:10.5598/imafungus.2015. (Open Access)

7. Musvuugwa, T., Dreyer, L.L. & Roets, F. 2015. The danger posed by ophiostomatoid fungi when encountering new hosts. Fungal Ecology Accepted. (IF = 2.99)

8. Schmickl, R., Liston, A., Zeisek, V., Oberlander, K.C., Weitemier, K., Straub, S.C.K., Cronn, R.C., Dreyer, L.L. & Suda, J. 2015.  Phylogenetic marker development for target enrichment from transcriptome and genome skim data: the pipeline and its application in Hyb-Seq of southern African Oxalis (Oxalidaceae). Molecular Ecological Resources doi: 10.1111/1755-0998.12487 (IF = 5.63)

9. Van der Colff, D., Dreyer, L.L. Valentine, A.J. & Roets, F. 2015.  Differences in physiological responses to infection by a native pathogen between a native forest and an exotic forestry tree. Fungal Ecology Accepted. (IF = 2.99)

10. Magadlela, A., Vardien, W., Kleinert, A., Dreyer, L.L. & Valentine A.J. 2015. Source of inorganic N affects the cost of growth in a legume tree species (Virgilia divaricata) from the Mediterrean-type Fynbos ecosystem.  Functional Plant Biology Accepted.