The University of Iowa
College of Liberal Arts and Sciences
The Department of Biology

Faculty Information

Diana Horton

Diana Horton

Professor Emeritus
Ph.D., University of Alberta (Canada) 1981
430B BB
(319) 335-1320

Currently not taking any students.
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Plant Systematics & Ecology

My research includes both systematic and ecological studies of plants, but I am, first and foremost, a taxonomist.

As a taxonomist, my focus is on the organism, and while all plants fascinate me, bryophytes (mosses, liverworts and hornworts) and especially the Encalyptaceae are my passion. The Encalyptaceae is a small family (two genera, ca. 25 species) of arctic-alpine mosses that is centred in the Northern Hemisphere. This family is characterized by unusual morphological diversity of the peristome, a structure that regulates spore dispersal and is considered highly significant in interpretations of moss evolutionary relationships. All aspects of the biology and evolution of the Encalyptaceae interest me.

My research on Encalyptaceae involves defining and describing taxa, and elucidating the evolutionary relationships among them. Field- and collections-based studies are the foundations of my investigations. I have collected extensively in North America, as well as in a few sites in Central and South America, and Europe. Taxa are delimited through analyses of inter- and intrapopulational variation in structure, habitat and geographic distribution, and evolutionary relationships are based on shared, derived character states.

Another aspect of my taxonomic research involves biodiversity studies of vascular plants and bryophytes, mainly in Iowa. The landscape here is deceptive. On the one hand, all one sees are corn and bean fields, a reflection of the wholesale habitat destruction that has taken place since European settlement, yet hidden away are tiny pockets of remnant natural habitats that give one a glimpse of what this land was. Although the flora of Iowa as a whole generally is well-known, there are many of these remnant habitats that never have been inventoried and the results can be surprisingly rich. My students, associates and I have documented the occurrence of more than ten native species never before recorded from the state and numerous new county records.

As an ecologist, I am vitally interested in utilizing the General Land Office (GLO) surveys to assess the fidelity of present-day vegetation to that recorded at the time of European settlement. The purpose of the GLO surveys was to lay out the legal grid of sections, townships and ranges on the landscape so that the government could begin to tax people based on location and how much land they were farming. Surveyors, who were woodsmen, were hired to do this work and they kept detailed records of the trees (when present) they used to mark the section corners and quarter-sections. The surveyors' data can be used to reconstruct the frequency, density and size of individual tree species. By comparing these data with those generated by inventories of the present-day vegetation, we are able to evaluate the quality of remnant habitats.

Keywords: Systematics of mosses; biodiversity studies of vascular plants and bryophytes; correlations between present-day vegetation and General Land Office survey data

Selected Publications

Cady, T.F. & D. Horton. 2004. Asplenium ruta-muraria L. in Iowa. Am. Fern J. 94: 30-32.

Horton, D. & P. Bergstrom. 2002. Iowa`s Fragile Flora: Rare and Endangered Plants website (formerly the University of Iowa Herbarium website). (

Baker, R.G., E.A. Bettis III, D. P. Schwert, D. G. Horton, C. A. Chumbley, L. A. Gonzalez & M. K. Reagan. 1996. Holocene paleoenvironments of northeast Iowa. Ecological Monographs 66: 203-234.

Horton, D.G. 1988. Microhabitats of New World Encalyptaceae (Bryopsida): Distribution along edaphic gradients, pp. 261 282. In Bryological Contributions. J. Engel & S. Hattori (eds.), Presented in celebration of the distinguished scholarship of Rudolf M. Schuster. Beih. Nova Hedwigia 90: 1 402.

Horton, D.G. 1983. A revision of the Encalyptaceae (Musci), with particular reference to the North American taxa. Part II. J. Hattori Bot. Lab. 54: 353 532.

Horton, D.G., D.H. Vitt & N.G. Slack. 1979. Habitats of circumboreal- subarctic Sphagna: I. a vegetation analysis and literature review of species in the Caribou Mountains, northern Alberta. Can. J. Bot. 57: 2283 2317.

Horton, D.G. 1977. Anastrophyllum assimile and Marsupella revoluta, new to the interior of North America. Can. J. Bot. 55: 2479 2484.