Image of the Library Building

Barbara M. Thiers

Patricia K. Holmgren Director, William and Lynda Steere Herbarium, Vice President, and Curator of Bryophytes

Ph.D., University of Massachusetts
Amherst, MA, 1982


Hepaticae (Liverworts)


Tropical Hepaticae, Herbarium Management, Biodiversity Information Management

Research locations

neotropics, worldwide


As Patricia K. Holmgren Director of the William and Lynda Steere Herbarium, I am responsible for overseeing the Garden’s 7.9 million collections of algae, bryophytes, fungi and vascular plants and the approximately 30 staff members who manage these collections. The Steere Herbarium is the largest in the Western Hemisphere, and third largest in the world. It is the world’s most heavily used herbaria in terms of the number of specimens loaned or imaged on demand, and the number of visitors to the Herbarium.

I have been particularly interested in the application of information technology to herbarium management, and to increasing access to specimen-based data for the scientific community. These interests have led to the development of The C. V. Steere Virtual Herbarium, which contains a searchable database of digitized herbarium specimens (4.5 million so far, with 400,000 added each year). I am also the Editor of includes Index Herbariorum, the guide to the world’s approximately 3300 herbaria and 12,000 associated staff. I have been involved in the development national initiatives to digitize the natural history collections in the U.S. as an author of the Network Integrated Biocollections Alliance plan, issued in 2010; as member of the Advisory Committee of the Biodiversity Collections Network; and the lead author of the Extended Specimen Network plan. I am also a co-author of the recent National Academies of Sciences and Engineering report on biological collections.

I am President of the American Society of Plant Taxonomists (2020-2021), Past President of Society for the Preservation of Natural History Collections (2020-2022), a member of the Board of the Natural Science Collections Alliance, and member of the External Advisory Board of iDigBio, the national collections digitization hub.

The subject of my research is the Hepaticae. In particular, I am interested in the systematics and morphology of the largest family of Hepaticae, the Lejeuneaceae. This family is primarily tropical in distribution, and its members can be found growing, often profusely, on the bark and sometimes on living leaves of trees in tropical rainforests. My studies of these small but beautiful plants have taken me to Australia, Colombia, Dominican Republic, Ecuador, French Guiana, Papua New Guinea, Puerto Rico and Venezuela.

I have a strong interest in the history of botanical collecting and the history of the herbarium; this interest has culminated in my book, Herbaria: The Quest to Preserve and Classify the World’s Plants (Timber Press, 2020).

Selected Publications

Selected Publications (Since 2010):

2010. (with W. Wayt. Thomas). O Jardim Botânico de Nova York e seu herbário virtual. Ciencia & Cultura (magazine of the Botanical Garden of Rio de Janeiro). Pp, 35—38. Jan—Mar 2010.

2011. (with J. Beach, L. Ford, R. Guralnick, M. Mares, M. Westneat and B. Wiegmann). Establishing a National Digital Biological Collections Resource –A strategic plan for establishing a network integrated biocollections alliance.

2010. with W. W. Thomas. From manuscript to the public: modes of monographic
publication in Stuessy & Lack, Monographic Plant Systematics: Fundamental Assessment of Plant Biodiversity. Regnum. Vegetabile 153. Gantner, Königstein. Herbaria. In: Public Garden Management by Donald A. Rakow , A. J. Wiley & Sons.

2012. With Tulig, M., N. Tarnowsky, M. Bevans, & A. Kirchgessner. 2012. Increasing the efficiency of digitization workflows for herbarium specimens. Zookeys. 209: 103-113.

2011. Notes on Early Land Plants Today. 11. Microlejeunea bischlerae (B. M. Thiers) comb. Nov. Phytotaxa 65: 59. DOI10.11646/phytotaxa.65.1.16

2013. With J. Hanken, L. McDade, J. Beach, J. Cook and L. Ford. An Implementation Plan for the Network Integrated Biocollections Alliance American Institute of Biological Sciences. Reston, VA.

2013. Thiers B.M., N. Wilson, R.E. Halling 2013. Making Scientific Vouchers of North American Macrofungi: How Documenting the Fungi You Encounter Contributes to the Mycoflora of North America. McIlvainea 22: 19-24.

2013. with Tulig, M. Tarnowsky, N., Bevans, M., and Kirchgessner, T. Digitizing the New York Botanical Garden Herbarium: The Holmgren Influence on the Past, Present, and Future. Memoirs of the New York Botanical Garden. 108:45-58. press.

2014. with 22 coauthors; C. Lamana, Lead Author. Functional Trait space and the latitudinal diversity gradient. Proceedings of the National Academy of Sciences 111: 1375-13750. DOI10.1073/pnas.1317722111

2016. with Matthew Pace Nicole Tarnowsky, et al. An updated description of the collections and history of The New York Botanical Garden Herbarium (NY-1995-2015). Brittonia 68: 317-323. DOI 10.1007/s12228-016-9422-8

2016. with M. Tulig and K. Watson. Digitization of The New York Botanical Garden Herbarium. Brittonia 68: 1007/s12228-016-9423-7. DOI 10.1007/s12228-016-9423-7

2016. with 4 other authors, G. Goldsmith, lead author. Cyberinfrastructure for an integrated botanical information network to investigate the ecological impacts of global climate change on plant biodiversity. DOI 10.7287/PEERJ.PREPRINTS.2615V1

2016. with 18 other authors, B. Enquist, lead author). Plant-O-Matic: a dynamic and mobile guide to all plants of the Americas. Methods in Ecology and Evolution. DOI10.1111/2041-210X.12548
2016. with 9 other authors, L. Krishtalka, lead author. Accelerating the discover of biocollections data. Technical Report. Global Biodiversity Information Facility

2017. with 21 other authors, B. S. Maitner, lead author. The bien r package: A tool to access the Botanical Information and Ecology Network (BIEN) database. Methods in Ecology and Evolution 9: DOI10.1111/2041-210x.12861

2018. with R. Halling. The Macrofungi Collection Consortium. Applications in Plant Science 7 p. Doi:10.1002/aps3.1021.

2018. Using natural history specimens to address national and global challenges. Informal Learning Review. 152: 12-16.

2018. with R. Rabeler, H. T. Svoboda, L. A. Prather, J. A. Macklin, L. Lagomarsino, L. C. Majure and C. J. Ferguson. Herbarium Practices and Ethics, III. Systematic Botany 44: 7-13. DOI: 10/1600/03634419X697840

2018. Book Review: Tropical Plant Collections: Legacies from the Past? Essential Tools for the Future? Henrik Balslev and Ib Friis, Editors. Systematic Biology

2019. with 33 other authors, B. Enquist, lead author. The commonness of rarity: Global and future distribution of rarity across land plants. Science Advances 5: eaaz0414. DOI: 10.1126/sciadv.aaz0414. With

2019. With J. Lendemer, A. K. Monfils, J. Zaspel, E. Ellwood, A. Bentley, K. LeVan, J. Bates, D. Jennings, D. Contreras, L. Lagomarsino, P. Mabee, L. Ford, R. Guralnick, R. Gropp, M. Revelez, N. Cobb, K. Seltmann, M. Aime. The Extended specimen network: A strategy to enhance U.S. Biodiversity Collections, Promote Research and Education. Bioscience biz140,

2020. With J. Collins, S. Pomponi, A. Bentley, R. Borchelt, K. Boundy-Mills, J. Cook, L. Dierking, S. Edwards, M. H. Hazbón, T. Karim, G. Matsumoto, P. Soltis. Biological Collections: Ensuring Critical Research and Education for the 21st Century. National Academy of Sciences Press. 210 pages. DOI 10.17226/25592.

2020. With A. Paton, A. Antonelli, M. Carine, R. Forzza, N. Davies, S. Demissew, G. Dröge, T. Fulcher, A. Grall, N. Holstein, M. Jones, U. Liu, J. Miller, J. Moat, J. Victor, T. Wilkinson, J. Dickie. Plant and fungal collections: Current status, future perspectives. Plants People and Planet. DOI: 10.1002/ppp3.10141.

2020. With D. Hobern, D. L. Paul, T. Robertson, Q. Groom, A. Asase, M. Lou, P. Semal, M. Woodburn, E. Zschuschen. Advancing the Catalogue of the World’s Natural History Collections BISS:Biodiversity Information Science and Standards 4:e59324. doi: 10.3897/biss.4.59324.

2020. Herbarium: The quest to preserve and classify the world’s plants. Timber Press. Portland, OR, 304 p. Publication date: 24 November 2020.

In Press:

Lejeuneaceae. Flora of North America. Vol. 22 Bryophytes part 2. 100 ms pages. Submitted 2010, revised 2013.

Pleuroziaceae. Flora of North America. Vol. 22 Bryophytes part 2. 6 ms pages September 2010, revised 2014.