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Appendix : Collection, Preparation, Handling, and Storage of Grass Specimens As noted in the ecoregion descriptions, many counties lack information on grass diversity. The following description of taxonomic practices is included to familiarize those who may not know the techniques for collecting and documenting plant species. Hopefully, this will encourage more collecting, particularly of grasses, throughout the state. Herbarium specimens are flattened, dried, permanently preserved, adequately documented , and properly stored plant materials . They are housed in a herbarium (plural, herbaria). Herbarium specimens are typically stored in cabinets. Historically, cabinets were made of wood, but they are mostly of metal construction today. The cabinets are partitioned into spaces designed to hold standard herbarium sheets. In some herbaria, specimens are stored in specially designed plastic containers with secure lids. These are particularly useful in tropical and humid areas where insects damage specimens. Sheets are grouped by species , placed in heavy paper folders, alphabetized , and stored accordingly. These specimens are the historical foundation of plant taxonomy; and as such, they are extremely valuable and, for all practical purposes, irreplaceable. Plant collections also are vital to such fields as plant anatomy, plant morphology, plant genetics, biosystematics, agronomy, biogeography, plant ecology, forestry , and range science. Figure A.1 shows the distribution of active herbaria across the state, and Table A.1 lists information about each herbarium . Following are some important uses of herbarium specimens. 1. Voucher specimens: This is perhaps one of the most important uses of herbarium specimens and relates to the plant nomenclatural process of typification. Beginning with Linnaeus’s Species Plantarium in 1753, plant names have been permanently fixed with specific herbarium specimens. When a taxonomist names a new taxon (i.e., genus, species, variety, etc.), often a single specimen is being described or the author may designate a specimen from all those examined that exemplifies the distinguishing features of the new taxon. The designated specimen is the holotype, also known as the nomenclatural type. As long as this specimen exists, the plant name is permanently fixed to it. Other forms of type specimens (isotype, lectotype, paratype, topotype, etc.) depend upon the known existence of the holotype and/or circumstances surrounding the description of the taxon (i.e., the paratype is a specimen cited in the original description but is not the holotype ) (Radford et al. 1974). Because of the importance of types, they are often 1036 appendix separated from the rest of the collections in herbaria to reduce unnecessary handling, and the types are usually more securely stored to guarantee their safety. Specimens may also validate records of plant structure, form, and characteristics used for taxonomic identification. They are especially important as voucher records in studies of chromosome number , polyploidy series, micromorphological characteristics, genetic relationships, and host plants. They enable other investigators to examine the exact specimens previously studied to ensure accuracy and validate results, an essential step in the scientific process. Voucher specimens are also used to document the occurrence of taxa from particular locations (e.g., military installations, conservation areas, wildlife preserves). 2. Records of distribution: Plant distributions found in floras, manuals, and checklists are almost always based on herbaria collections. Records of occurrence by county, plant community, ecosystem, ecoregion, state, and so forth are also based on permanently mounted specimens stored in herbaria. Collections provide a valuable historical record of where plants have occurred in both space and time. Specimens can document when and where foreign weeds were introduced (Diggs, Lipscomb, and O’Kennon 1999). Distributional data are extremely important to plant biogeographers and plant ecologists. Poole et al. (2007) concluded that the flora of Texas remains poorly understood compared to the flora of other states. Texas is a large state, and over 90% of Figure A.1. Distribution of active herbaria in Texas. Table A.1. Herbaria in Texas. Herbarium code Address Number Specialty ASTC Biology Department 78,000 Eastern Texas Stephen F. Austin University P.O. Box 13003 SFA Station Nacogdoches, TX 75962-3003 BAYLU Biology Department 61,000 Texas Baylor University Baylor Sciences Building A254 Waco, TX 76798-7388 BRCH Botanical Research Center 9,000 Texas; southern U.S.; P.O. Box 6717 northeastern Mexico Bryan, TX 77805-6717 BRIT Botanical Research Institute 1,000,000 Worldwide, especially 509 Pecan Street Texas; southeastern U.S. Fort Worth, TX 76102-4060 HABAYC Biology Department 2,249 Texas University of Mary Hardin-Baylor Belton, TX 76513-2599 HPC Biology Department 40,000 Central Texas, especially Howard Payne University Edwards Plateau; Brownwood, TX 76801 Sonora and Baja, Mexico HSU...

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Additional Information

ISBN
9781603446747
Related ISBN
9781603441865
MARC Record
OCLC
794003392
Pages
832
Launched on MUSE
2012-06-26
Language
English
Open Access
No
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