- Vascular plant specimens follow the standard format, in that pressed plants of a given individual (whole or in part) are taped or glued to an herbarium sheet of 16.6 x 11.5 inches. Specimen labels on acid-free, 100% cotton bond paper, are attached to the Specimen photolower right corner of the herbarium sheet. Loose parts or fragments of plant organs are included in envelopes attached to the herbarium sheet.
- Bryophytes and lichens are placed in standard bryophyte envelopes, which are then attached to the herbarium sheet. Several specimens of a given taxon may be mounted on the same sheet. If the specimens are very large, they will be stored in appropriately sized boxes. The boxes will be labeled and stored in a separate place in the herbarium.
- Algae and some fungi will be stored in 60% ethanol with a small amount of glycerin added to prevent loss of gross morphology as a result of drying.
Arrangement and Care of Specimens
Specimens in the TWU Herbarium are arranged alphabetically by families and genera to facilitate quick and easy access. Specimens will be stored in airtight, insect-proof herbarium cases geographically arranged, as stated above. An updatable Curation Table database will record information on families and genera that need and have been receiving curational treatment, such as backlog mounting, literature extraction, databasing, etc. The following issues are to be taken into consideration on curating activities:(1) revisiting identification and annotating name changes; update names to the contemporary standards and apply correct botanical names to the specimens; (2) extract unidentified, suspected misidentified, and other problem specimens and file them under In Work; (3) remounting/mounting on acid-free herbarium paper; (4) extract and annotate type specimens; (5) rearrange mixed collections and make new regional folders.
The following areas must be taken into consideration when caring for of the collection:
- Pest control - prevention and treatment: All incoming material is fumigated or dry-frozen prior to entering the collection storage area to minimize the potential for insect infestation. Periodic checks are conducted to detect signs of infestation. Should such signs become evident, the affected areas are treated in the appropriate manner.
- Fire prevention
- Adequate and appropriate storage space
- Shipping and receiving of specimens
- Discarding specimens
Accession Numbers and Records
Each specimen in the TWU Herbarium is given an accession number. Accession numbers are assigned consecutively and placed within the herbarium accession label, on the lower left corner of the specimen sheet or on the specimen envelope in case of bryophytes, etc. The accession number will be stamped on the specimen label itself, to help re-matching the label to the specimen in case the label gets separated from the specimen sheet.
Accessions are recorded in a record book with all appropriate data, including the date that the specimens were accessioned. In addition to the record book of the collection, all specimen data is available on a searchable computer database.
Acquisition of Specimens
Only specimens of very good (plenty of material) and identifiable quality will be accepted as donations or exchange items. The above specimens as well as those collected by the Herbarium personnel must be adequately labeled, include complete collection data, and must be identified by a staff member who can provide the proper determination. All records regarding matter of acquisition are kept by the Collection Manager. It is the TWU Herbarium personnel's responsibility to ensure that all acquired specimens are obtained legally and that the provenience of the specimens is clear.
Procedures for Restoration of Damaged or Deteriorated Specimens
Attention to restoration will be given on a situation basis. No specimens will leave the TWU Herbarium on loan unless they meet highest standards of quality. An 'in process' cabinet will be initiated for specimens in need of restoration and repair.
Only acid-free paper will be used for the TWU Herbarium. Old sheets of acid-based paper should be remounted. If the specimen is attached by tape, it can be removed from old paper entirely and remounted on acid-free paper. If the specimen was glued to the old paper, as much of the sheet as possible should be cut away before the specimen can be remounted on acid-free paper. It is imperative that all labels and any forms of writing on the old sheet be cut out and saved and attached to the new sheet. Any label from a historically significant collector or associated with a historically significant collection should not be removed or tampered with unless in a necessary restoration.
Only good quality, reversible, white glue will be used to restore the specimens. Standard herbarium-quality cloth tapes can be used, but no transparent tape should be used for the purpose of the specimen mounting.
Loose parts of the specimens will be either placed in envelopes attached to the sheet or re-glued to the sheet in the original place prior to breakage or on another area of the herbarium sheet.
The goal of the TWU Herbarium staff is to avoid discarding of damaged specimens by properly curating the collection. However, for the beginning, specimens can be discarded in the following instances:
- The specimen has no collection date recorded
- The specimen has absolutely no location data
- There are at least five specimens of the same taxon already in the Herbarium
- The specimen is not particularly rare or infrequent in the natural world
- The specimen was not collected or identified by a renowned or noteworthy collector
All of the above criteria must be met before specimens can be discarded. When the discarded specimen is removed from the herbarium, its accession number, information, and justification for discard should be recorded in a notebook for discarded specimens. If the specimen has been recorded on a computer database, make note that the specimen has been discarded.
Correspondence represents a historical record of not only the Herbarium and its scientists, but of plant taxonomy as well. We are very interested in hearing from the TWU Herbarium users and potential users. Any questions, comments, or suggestions should be addressed to:
or by regular mail at:
The TWU Herbarium
P.O. Box 425799
Denton, Texas 76402-5579
Copies of letters under any format, e-mail, regular mail, fax, sent out or received are placed in separate three-ring binders stored in the Herbarium room.
page updated 10/28/2015 2:19 PM