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A diverse group of fungi, including rusts, yeasts, smut-like and jelly-like fungi

Elizabeth M. Frieders, David J. McLaughlin, and Les J. Szabo
taxon links [down<--]Basidiomycota [up-->]Septobasidiales [up-->]Uredinales Phylogenetic position of group is uncertain Phylogenetic position of group is uncertain Phylogenetic position of group is uncertain [up-->]Mixia osmundae Phylogenetic position of group is uncertain Interpreting the tree
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Containing group: Basidiomycota


Members of the class Urediniomycetes are remarkably diverse, possessing a wide range of structural and ecological characters. One characteristic many of these fungi have in common, however, is their rather miniscule size, making them challenging to locate and study. The apparent lack of unifying structural features of many members of the Urediniomycetes has presented a challenge to understanding their phylogenetic affiliations, and the relationships of many of these disparate taxa have been illuminated since 1995 through the acquisition of molecular sequence, biochemical and subcellular data.

The class contains approximately 7,400 species, distributed among approximately 215 genera, but will eventually be much larger as many cryptic species are recognized. More than 95% of the species and 75% of the genera in this class are placed in the Uredinales, the plant parasitic rust fungi. The next largest orders, Septobasidiales and Microbotryales, collectively constitute approximately 5% of the species and 4% of the genera. Nearly 20% of the rust genera and 60% of the nonrust genera are monotypic (containing only one species). The rust fungi and several of the yeasts have been more extensively studied than have other taxa, and the surprisingly large percentage of monotypic genera may be artificially high due to the limited research on these often obscure fungi.

The rusts are undeniably the most economically important fungi in this clade, as obligate parasites on a wide range of crop plants including cereal grains, legumes, and trees such as coffee, apple, and pine, where they can cause extensive reduction in yield and even host death. Other phytopathogenic Urediniomycetes can be of economic importance, but on a much smaller scale than rust fungi. Species of Helicobasidium cause root rot diseases of many economically important plants such as asparagus, beet, mulberry, and pear. Microbotryum violaceum causes anther smut of plants in the Caryophyllaceae, while smut on buckwheat is caused by Sphacelotheca fagopyri. These smuts are not closely related to the smuts in the Ustilaginomycetes with which they were confused until molecular sequence data became available.

For a more thorough overview of the class Urediniomycetes, see Swann et al. (2001); see Fell et al. (2001) for additional details of urediniomycetous yeasts.

Information on the Internet

Title Illustrations
Scientific Name Eocronartium muscicola
Specimen Condition Live Specimen
Identified By D.J. McLaughlin
Life Cycle Stage fruitbodies on moss host
Collection MIN 864444
Collector David J. McLaughlin
Copyright © 2001 Bell Museum of Natural History
Scientific Name Hemileia vastatrix, Coffee Rust
Location Las Cruces, Costa Rica
Specimen Condition Live Specimen
Identified By D. J. McLaughlin
Behavior on leaves of Coffea
Life Cycle Stage uredinial stage
Collection MIN862012
Copyright © 1995 Elizabeth M. Frieders
Scientific Name Helicobasidium purpureum Pat.
Location Germany, Baden-W?rttemberg, T?bingen
Specimen Condition Live Specimen
Identified By M. Lutz
Behavior on Picea abies (L.) Karst.
Life Cycle Stage fruitbody of the phytoparasitic teleomorph
Collection TUB 012601
Collector M. Lutz
Copyright © 2005
About This Page

Elizabeth M. Frieders

Department of Biology
University of Wisconsin-Platteville
Platteville, WI 53818-3099

David J. McLaughlin

Department of Plant Biology University of Minnesota
220 Biological Science Center
1445 Gortner Ave.
St. Paul, MN 55108

Les J. Szabo

USDA-ARS Cereal Disease Laboratory
1551 Lindig Street
University of Minnesota
St. Paul, MN 55108

Correspondence regarding this page should be directed to Elizabeth M. Frieders at

Citing this page:

Frieders, Elizabeth M., McLaughlin, David J., and Szabo, Les J. 2005. Urediniomycetes. A diverse group of fungi, including rusts, yeasts, smut-like and jelly-like fungi. Version 01 January 2005 (under construction). http://tolweb.org/Urediniomycetes/20528/2005.01.01 in The Tree of Life Web Project, http://tolweb.org/

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