Grasses of the Intermountain Region
Utah State University
Copyright © 2009 Intermountain Herbarium, Utah State University
All right reserved. ISBN: 978-0-87421-765-0Contents
Preface.....................................viiAuthors of treatments.......................ixAbbreviations...............................xiTaxonomic Treatments........................1Key to Tribes...............................5BAMBUSOIDEAE................................71. Bambusa..................................72. Phyllostachys............................83. Pseudosasa...............................8EHRHARTOIDEAE...............................81. EHRHARTEAE...............................92. ORYZEAE..................................10POOIDEAE....................................113. NARDEAE..................................124. MELICEAE.................................135. STIPEAE..................................226. BROMEAE..................................377. TRITICEAE................................508. POEAE....................................80ARUNDINOIDEAE...............................1709. ARUNDINEAE...............................171CHLORIDOIDEAE...............................17310. CYNODONTEAE.............................17411. PAPPOPHOREAE............................223DANTHONIOIDEAE..............................22312. DANTHONIEAE.............................224ARISTIDOIDEAE...............................22713. ARISTIDEAE..............................228PANICOIDEAE.................................23414. PANICEAE................................23515. ANDROPOGONEAE...........................257Illustrations...............................275Distribution Maps...........................491Literature Cited............................515Index.......................................525Abbreviations...............................559
Preface
Grasses of the Intermountain Region is a modification of the two grass volumes of the
Flora of North America (FNA). It is designed for identifying members of the
Poaceae in the region between the Sierra Nevada and Rocky Mountains. The reduction in the number of taxa treated has reduced the length of the keys and made it possible to include, in a single volume, descriptions and illustrations for all taxa treated as well as provide distribution maps for species that are established in the area.
Region: In this volume, the Intermountain Region is interpreted somewhat more broadly than in the Intermountain Flora (see Cronquist et al. 1972), differing primarily by 1) including, in addition to the regions covered by that flora, the southern tip of Nevada; 2) using the crest of the Sierra Nevada, rather than the lower slopes, as the western boundary; 3) using the Colorado River as the southern boundary in Arizona; and 4) using county boundaries (rather than geographic boundaries) to define its limits in Oregon, Idaho, and Wyoming. This last explains the rather jagged boundaries of the distribution maps.
The reason for using county boundaries was pragmatic. Information on which species grow in the region comes from plants preserved as herbarium specimens, the labels of which provide information on when, where, and by whom they were collected. This information almost always includes the name of the county in which the specimen was collected but, because most were collected before development of inexpensive GPS units, obtaining more precise information is a major task. This situation is, however, changing rapidly thanks to the major push by herbaria to georeference their collections.
Maps: The distribution maps are based on information from herbarium specimens and published sources. Two levels of data are represented. The gray areas represent counties in which the species has been collected; the dots reflect the actual collection location. Many of these dots were obtained by retrospectively georeferencing information on specimen labels. As such, their accuracy varies but they provide better information than relying entirely on county records. It should also be borne in mind that many of these specimens are old; some of the localities shown have since become part of a town, golf course, highway, field, or other constructed landscape.
For determining whether a species from Arizona, California, or Oregon was collected within the region, we consulted http://ucjeps.berkeley.edu/consortium/, http://swbiodiversity.org/seinet/index. php, and http://www.oregonflora.org/atlas.php. If we were still unable to determine whether a species was inside or outside the region, we included it.
The maps in this volume incorporate some updates from the information in the FNA volumes and the Manual of Grasses for North America, but we have not reviewed them all. The maps are also available online at http://herbarium.usu.edu/webmanual. This online resource provides additional information about the source of individual records and is updated at irregular intervals. For information about a particular record or to provide additional records, contact mary@biology.usu.edu.
Organization: To conserve space, the descriptions, illustrations, and distribution maps are in three separate sections and abbreviations have been used in the descriptions. The order in which the taxa are treated reflects their phylogenetic relationships, as these are now understood. Grouping the treatments in this manner makes it easier to locate and compare the descriptions and illustrations of similar genera and species than does an alphabetical arrangement.
A bipartite number is used to indicate the location of each genus, the part before the dot indicating the tribe and the part after the dot indicating the genus. These numbers also form part of the page headers. In the generic treatments, the names of the species are followed by two page numbers; the italicized number refers to the illustration page, the underlined number to the map page. Tripartite numbers are associated with each illustration and map. The first two parts of these numbers correspond to the tribal and generic numbers used as page headers on the treatment pages; the third part of each number indicates the position of the species within the text material for its genus. The literature cited section includes all the works cited in this volume. For a more extensive listing, readers should consult the Flora volumes or go online at http://utc.usu.edu/grassbib.htm.
Numbers: There are 482 species described in this volume. They represent five subfamilies, 15 tribes, and 134 genera. These numbers include six hybrid genera, mostly in the Triticeae, and six hybrid species. Of the 482 species, 286 are native and known to be in the region, 101 are introduced species that are established in the region, and 44 are cultivated. Most of the cultivated species are grown as ornamentals but some, such as wheat (Triticum aestivum) and corn (Zea mays), are grown for food or forage. Of the established species some, such as crested wheatgrass (Agropyron cristatum), were deliberately introduced; the introduction of others, such as medusahead (Taeniatherum caput-medusae), was accidental. The status of the other 51 species in the region (including the hybrid species) is in doubt for one reason or another. Some of them are species known to grow in adjacent areas, but whether they actually extend into the region is not known. For other species, it is doubtful whether they are native or introduced to the region from other parts of North America.
A few species that are not thought to be established have been included. Some of these, such as Hygroryza aristata, seem likely to become aggressive weeds if they escape. A few species, such as Glyceria declinata and Ehrharta calycina, are known only from old collections and are probably no longer present in the region. Piptochaetium lasianthum is included because it was, tentatively, reported from the region by Welsh et al. (2003, 2007). The specimen proved to be an Achnatherum hymenoides hybrid.
Taxonomic changes: There are some differences between the taxonomic treatments in this volume and its two predecessors, the grass volumes in the Flora of North America series and the Manual of Grasses for North America. The changes include recognition of both Podagrostis humilis and P. thurberiana, treatment of Buchlo dactyloides as a species of Bouteloua, and recognition of Distichlis spicata subsp. spicata based on evidence from a 2009 abstract. The additional taxa have been illustrated by Dr. C.T. Roch. She has also prepared new illustrations for some of the original plates in which the habit was illustrated by a taxon from outside the region.
The name Thinopyrum ponticum, which is based on Triticum ponticum Podp., needs to be changed. Tsvelev (1993) made it a synonym of Elytrigia obtusiflora, based on Triticum obtusiflorum DC. While checking type specimens, it became evident that there may be earlier epithets available. In order to avoid adding to the confusion by combining "obtusiflorum" with Thinopyrum and then finding an earlier epithet, we have continued to use Thinopyrum ponticum in this volume.
Synonyms: Many of the taxa treated in this volume are treated under other names in older floras. The index includes all such names, showing the name used in this volume and the page on which its description is located.
Authorship: Most of the these treatments are drawn nearly directly from those in the Flora of North America volumes, and their authorship is usually the same as in those volumes. The FNA authors were sent copies of the modified versions for approval. Some suggested ways in which the modified versions could be improved, for which we thank them. In a few cases, there has been a change of authorship either because the treatment has been changed or the author no longer wishes to be involved. The citation for the volume is:
Anderton, L.K. and M.E. Barkworth (Eds). 2009. Grasses of the Intermountain Region. Intermountain Herbarium. 559 pp.
Acknowledgments:. In addition to the the authors of the treatments, we thank Dr. Kanchi Gandhi, Harvard University, for his rapid and careful responses to all our nomenclatural questions, Dr. Cindy Roch for the additional illustrations, Chris Garrard for modifying our mapping program to create the maps used in this volume, and John Lowry for developing the maps for the front end pages. We also thank SEINet, the California Consortia of Herbaria, and the Flora of Oregon project for making
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