Conservation and restoration of herbaria

Last updated January 16, 2024

The conservation and restoration of herbaria includes the preventive care, repair, and restoration of herbarium specimens. Collections of dried plant specimens are collected from their native habitats, identified by experts, pressed, and mounted onto archival paper. Care is taken to make sure major morphological characteristics are visible. Herbaria documentation provides a record of botanical diversity.^[1]

Professionals who make decisions about the conservation-restoration of botanical specimens include registrars, curators, and conservators who work on herbarium collections in universities and museums. Herbarium specimens may be susceptible to water damage, mold, pests, unattached specimens, dust, dirt, and damage from improper storage conditions. Preventive conservation can prevent much of the damage that could occur.

History

A herbarium is a collection of preserved plant specimens and associated data used for scientific study.^[2] Originally, the word "herbarium" referred to books about medicinal plants. In 1700, French botanist Joseph Pitton de Tournefort used the word to describe a collection of dried plants and Carl Linnaeus continued to use this term in his work which is where the term caught on. Initially, herbarium collections were bound in volumes instead of on individual sheets as it is done today.^[3] It is not exactly known how long dry plant specimens last in storage, but with proper conservation, they have been able to last many years. Specimens collected by Linnaeus in the eighteenth century and by Banks and Solander on the Endeavour voyage in 1788 are still excellently preserved.^[4] The specimens may be whole plants or plant parts. These will usually be dried and pressed and mounted on a sheet of paper but, depending upon the material, may also be stored in boxes or kept in alcohol or other preservatives.^[5]

Types of specimens

Pressed and dried: Vascular plant (flowering plants, conifers, ferns) specimens are pressed and dried plants that are mounted on herbarium sheets. Various techniques are used to attach the plants with the most common method of using archival adhesive with heavier portions of the plant supported additionally by linen thread or narrow strips of gum-backed linen tape or polyester film. Specimens are best pressed with moderate pressure, permitting as much air circulation as possible. This is commonly achieved by strapping sheets in a press made of heavy cardboard or plywood.^[4] If there are loose seeds or fruits, these are placed in a small fragment packet, which also is glued to the sheet. A label with collection information is glued on the bottom right corner.
Dried: Small bryophytes (mosses, hepatics or liverworts, and hornworts) are dried and placed loosely in folded packets. The label is glued on the front of the packet and the packets are filed loosely in boxes, glued to sheets of mounting paper, or placed loosely in folders.^[6]
Stored in fluid: Preserved material can be kept in a glass jar filled with preservative fluid. By storing this way, the botanical specimens are maintained in a usable condition by inhibiting enzymatic and microbial attack.^[7] This method can be used where drying, pressing and mounting on a herbarium sheet is unsuitable. This method allows for a better three-dimensional arrangement of flower parts or fruits for storage.
Microscope slides: Specimens can be mounted on microscope slides for short-term storage, however, there is a greater risk of rapid deterioration from contracting, darkening, or crystallizing specimens. Slides should be checked on an annual basis to check the condition of preserved specimens.^[8]
Desiccants and freeze-drying: Silica gel or freeze-drying methods can be applied to specimens that require preservation of the shape of a delicate organ such as a flower. Disadvantages of this technique are that the specimen is especially fragile and lacks support. Acid-free tissue is often used for storage.^[4]

Agents of deterioration

The practice of preventive conservation is the management of fluctuations in temperature, light, relative humidity, pests, and pollutants that can deteriorate museum collections.^[9] These factors are considered agents of deterioration. Understanding the practice of preventive conservation as well as the agents of deterioration is most important when trying to protect, display, and store collections within the conservation field.

Physical forces

Proper storage in secure and stable shelving will allow for less stress and movement to affect plant collections. Dried and pressed plant specimens can be stored best in archival-grade boxes, or tied in bundles in cardboard folders for long-term storage. For collections that may be handled more frequently, specimens can be placed in archival-grade plastic sheets placed in ring folders.^[4]

Disaster recovery

Water damage resulting from flooding can result in shrinking, distortion, or staining of plant materials.^[10] Unforeseen disasters can occur at any time and disaster recovery planning and materials for herbaria are similar to museums and libraries. Little can be done with burnt specimens and fragmented specimens except to preserve and protect what is left intact. The damage most likely to occur is water damage through natural or man-made flooding, such as roof leakage or fire sprinkler malfunction. Damaged or waterlogged specimens are frozen to delay deterioration and prevent a fungal attack, which gives curators time to evaluate the situation and decide how best to approach the problem.

Pests

Common herbarium pests include: silverfish, book lice (psocids), cigarette or tobacco beetles (Lasioderma), dermestids, drugstore beetles (Stegobium paniceum) ^[5] A reoccurring threat to the longevity of herbarium specimens is insects, a number of which find dried plants palatable. Historically, various methods have been used to kill insects, which either come in with the plants when they are collected or are in the building where the plants are stored.^[6] Pests are commonly treated with two different methods:

Freezing: Using a clear polyester bag, excess air is pushed out and heat sealed with the specimen inside or the specimen can be placed inside polythene bags and sealed with parcel tape. Then it is placed into a normal domestic freezer for at least 14 days at a temperature of −18 °C (0 °F), or for 72 hours if freezing at −30 °C (−22 °F).
Anoxia: Small anoxic environments starve the pests of oxygen and are created using sealed barrier films and placing oxygen scavengers and RH buffers inside before sealing.^[11]

An integrated pest management program is cost-effective over time and the best preventive measure against pests.

Fungal attack

The primary risk factor for fungal attack is incomplete drying of specimens, caused either during the specimen preparation process or afterwards, or in collections that become wet later through flood, other water damage or improper storage conditions, especially in the tropics. Properly dried plant specimens will not suffer from fungal attack if stored in the correct conditions. During the drying process specimens are particularly at risk if they dry slowly. This happens through poor drying conditions or specimens being wet before being pressed or having water-retaining or succulent parts. Specimens with sugary exudations or large quantities of nectar are also particularly attractive to fungi and need special care during drying to ensure that they dry fast enough to prevent mold growth. If fungal growth occurs on specimens, it can be brushed with 95% ethanol or methylated spirits (denatured alcohol). However, this may alter the specimen for chemical and other investigative research and only kills the fungus present on the specimen, not preventing further problems of fungal growth.^[12]

Light

Herbarium specimens are sensitive to visible light and ultraviolet radiation, which can cause fading of biological pigments (fading or shifts in color) and/or damage to chemical bonds (weakened or embrittled).^[13]

Theft

To best establish protocols for specimen movement control, a system of documentation can be set up to monitor and control collections.^{[ citation needed ]} At the National Museum of Natural History, theft is prevented by maintaining limited access to where collections are stored. In the event of a specimen leaving the site through outgoing loans, records are kept which gather letters of request, the transmission of names, and other supporting documentation.^[14]

Pollutants

Storage in metal cabinets is the best material to maintain herbaria collections. Metal cabinets do not release volatile organic compounds as wooden cabinets do. The metal shelves can be easily cleaned and a well-sealed cabinet will provide a stable microclimate for the specimen.^[15]

Disassociation

Ensuring that every specimen has an individual accession number will reduce the risk of disassociation. The accession number relates that number to an identifiable object and the object can only be moved if its location is updated, ensuring the object is never disassociated from its data. Most herbaria utilize a standard system of organizing their specimens into herbarium cases. Specimen sheets are stacked in groups by the species to which they belong and placed into a large lightweight folder that is labeled on the bottom edge. Groups of species folders are then placed together into larger folders by genus. The genus folders are then sorted by taxonomic family according to the standard system selected for use by the herbarium and placed into pigeonholes in herbarium cabinets.^[4] Locating a specimen filed in the herbarium requires knowing the nomenclature and classification used by the herbarium. It also requires familiarity with possible name changes that have occurred since the specimen was collected, since the specimen may be filed under an older name. Modern herbaria often maintain electronic databases of their collections. Many herbaria have initiatives to digitize specimens to produce a virtual herbarium. These records and images are made publicly accessible via the Internet when possible.

Repair and restoration

Before beginning the process of restoration of a herbarium sheet, best practices suggest that the original mounted specimen be photographed for reference to ensure a new sheet is as close to the original as possible. The original mounting sheet can be dried and flattened in the same manner as the plant to serve as a reference for positioning the specimen on a new sheet. Additionally, any labels or supplement information accompanying the plant should be placed in the same place.^[16]

Cleaning

Dust and dirt are removed from herbarium sheets by using a smoke sponge. Conservators gently rub the place where the dirt is and then softly remove any excess with a fine brush. Care must be taken by conservators when dealing with older prepared specimens that may have traces of toxic chemicals. Making use of personal protective equipment by professionals can reduce the risk of exposure or harm due to dangerous materials.

Broken specimens

Broken specimens are reattached to the herbaria sheet using thinly cut strips of archival pre-gummed linen tape. Detached materials such as seeds or leaves are placed in an acid-free card fragment packet, which is secured onto the sheet with the original specimen.

Removal from mounting sheet

Unattached specimens are removed from the herbaria sheet by humidifying it to make them pliable and removing the plant with a paper lifter (smooth wooden spatula). They are then placed to dry and flatten along with the original mounting sheet and written documentation (label and annotations). The specimen and original documents are then remounted to a new sheet using the original sheet as reference.

Related Research Articles

A herbarium is a collection of preserved plant specimens and associated data used for scientific study.

Plant collecting is the acquisition of plant specimens for the purposes of research, cultivation, or as a hobby. Plant specimens may be kept alive, but are more commonly dried and pressed to preserve the quality of the specimen. Plant collecting is an ancient practice with records of a Chinese botanist collecting roses over 5000 years ago.

<span class="mw-page-title-main">Conservation and restoration of parchment</span> Preservation of heritage collections

The conservation and restoration of parchment constitutes the care and treatment of parchment materials which have cultural and historical significance. Typically undertaken by professional book and document conservators, this process can include preventive measures which protect against future deterioration as well as specific treatments to alleviate changes already caused by agents of deterioration.

The conservation and restoration of textiles refers to the processes by which textiles are cared for and maintained to be preserved from future damage. The field falls under the category of art conservation, heritage conservation as well as library preservation, depending on the type of collection. The concept of textile preservation applies to a wide range of artifacts, including tapestries, carpets, quilts, clothing, flags and curtains, as well as objects which "contain" textiles, such as upholstered furniture, dolls, and accessories such as fans, parasols, gloves and hats or bonnets. Many of these artifacts require specialized care, often by a professional conservator.

Conservation and restoration of movable cultural property is a term used to denote the conservation of movable cultural property items in libraries, archives, museums and private collections. Conservation encompasses all the actions taken toward the long-term preservation of cultural heritage. Activities include examination, documentation, treatment, and preventive care, which is supported by research and education. Object conservation is specifically the actions taken to preserve and restore cultural objects. The objects span a wide range of materials from a variety of cultures, time periods, and functions. Object conservation can be applied to both art objects and artifacts. Conservation practice aims to prevent damage from occurring, a process known as 'preventive conservation'. The purpose of preventive conservation is to maintain, and where possible enhance, the condition of an object, as well as managing deterioration risks, such as handling and environmental conditions. Historically, object conservation was focused on the category of fine arts but now many different types of objects are conserved. Each type of object material, typically denoted by organic or inorganic then the specific medium, requires a specialized professional conservator and often requires collaborative work between museum staff, scientists, and conservators.

Collection maintenance is an area of collections management that consists of the day-to-day hands on care of collections and cultural heritage. The primary goal of collections maintenance or preventive conservation is to prevent further decay of cultural heritage by ensuring proper storage and upkeep including performing regular housekeeping of the spaces and objects and monitoring and controlling storage and gallery environments. Collections maintenance is part of the risk management field of collections management. The professionals most involved with collections maintenance include collection managers, registrars, and archivists, depending on the size and scope of the institution. Collections maintenance takes place in two primary areas of the museum: storage areas and display areas.

The conservation and restoration of books, manuscripts, documents, and ephemera is an activity dedicated to extending the life of items of historical and personal value made primarily from paper, parchment, and leather. When applied to cultural heritage, conservation activities are generally undertaken by a conservator. The primary goal of conservation is to extend the lifespan of the object as well as maintaining its integrity by keeping all additions reversible. Conservation of books and paper involves techniques of bookbinding, restoration, paper chemistry, and other material technologies including preservation and archival techniques.

The conservation and restoration of flags and banners is the process by which conservators work to preserve and restore flags and banners from future deterioration and damage. As a part of Conservation of Textiles, flag and banner conservation require the care of a skilled and well trained textile conservator, specifically trained in historical materials.

The conservation and restoration of feathers is the practice of maintaining and preserving feathers or featherwork objects, and requires knowledge of feather anatomy, properties, specialized care procedures, and environmental influences. This practice may be approached through preventive and/or interventive techniques.

Conservation-restoration of bone, horn, and antler objects involves the processes by which the deterioration of objects either containing or made from bone, horn, and antler is contained and prevented. Their use has been documented throughout history in many societal groups as these materials are durable, plentiful, versatile, and naturally occurring/replenishing.

The conservation and restoration of paintings is carried out by professional painting conservators. Paintings cover a wide range of various mediums, materials, and their supports. Painting types include fine art to decorative and functional objects spanning from acrylics, frescoes, and oil paint on various surfaces, egg tempera on panels and canvas, lacquer painting, water color and more. Knowing the materials of any given painting and its support allows for the proper restoration and conservation practices. All components of a painting will react to its environment differently, and impact the artwork as a whole. These material components along with collections care will determine the longevity of a painting. The first steps to conservation and restoration is preventive conservation followed by active restoration with the artist's intent in mind.

The conservation and restoration of woodblock prints, is the process of caring for and repairing images made from a specific printing process involving using wooden reliefs to stamp or imprint an image onto paper. The process of creating woodblock prints as Asian examples are known, or woodcuts as Western examples are called, has been known for many centuries, and many older prints have experienced aging and deterioration of the paper and colorants used.

The conservation and restoration of film is the physical care and treatment of film-based materials. These include photographic film and motion picture film stock.

The conservation of taxidermy is the ongoing maintenance and preservation of zoological specimens that have been mounted or stuffed for display and study. Taxidermy specimens contain a variety of organic materials, such as fur, bone, feathers, skin, and wood, as well as inorganic materials, such as burlap, glass, and foam. Due to their composite nature, taxidermy specimens require special care and conservation treatments for the different materials.

The conservation-restoration of panel paintings involves preventive and treatment measures taken by paintings conservators to slow deterioration, preserve, and repair damage. Panel paintings consist of a wood support, a ground, and an image layer. They are typically constructed of two or more panels joined together by crossbeam braces which can separate due to age and material instability caused by fluctuations in relative humidity and temperature. These factors compromise structural integrity and can lead to warping and paint flaking. Because wood is particularly susceptible to pest damage, an IPM plan and regulation of the conditions in storage and display are essential. Past treatments that have fallen out of favor because they can cause permanent damage include transfer of the painting onto a new support, planing, and heavy cradling. Today's conservators often have to remediate damage from previous restoration efforts. Modern conservation-restoration techniques favor minimal intervention that accommodates wood's natural tendency to react to environmental changes. Treatments may include applying flexible battens to minimize deformation or simply leaving distortions alone, instead focusing on preventive care to preserve the artwork in its original state.

The conservation and restoration of insect specimens is the process of caring for and preserving insects as a part of a collection. Conservation concerns begin at collection and continue through preparation, storage, examination, documentation, research and treatment when restoration is needed.

The conservation and restoration of photographic plates is caring for and maintaining photographic plates to preserve their materials and content. It covers the necessary measures that can be taken by conservators, curators, collection managers, and other professionals to conserve the material unique to photographic plate processes. This practice includes understanding the composition and agents of deterioration of photographic plates, as well as the preventive conservation and interventive conservation measures that can be taken to increase their longevity.

The conservation and restoration of quilts refers to the processes involved in maintaining the integrity of quilts and/or restoring them to an acceptable standard so that they may be preserved for future generations. Quilts have been produced for centuries, as utilitarian blankets, decorations, family heirlooms, and now treasured museum collections objects. Quilts are three-layered textile pieces with a decorated top, a back, and a filler in the middle. The composite nature of these objects creates an interesting challenge for their conservation, as the separate layers can be made of different textile materials, multiple colors, and therefore, varying degrees of wear, tear, and damage.

The conservation and restoration of waterlogged wood is the process undertaken by conservator-restorers of caring for and maintaining waterlogged wooden artefacts to preserve their form, and the information they contain. It covers the processes that can be taken by conservators, archaeologists, and other museum professionals to conserve waterlogged wood. This practice includes understanding the composition and agents of deterioration of waterlogged wood, as well as the preventive conservation and interventive conservation measures that can be taken.

References

↑ "What Does the Herbarium Do?". Brown University . Retrieved 5 December 2023.
↑ "What is a herbarium". Royal Botanic Garden Edinburgh. Archived from the original on 6 March 2016. Retrieved 10 April 2017.
↑ "What is an herbarium?". Brown University.
1 2 3 4 5 "Preserving Plant Specimens". The Royal Botanic Garden Sydney.
1 2 "Conserve O Gram – Preparing and Storing Herbarium Specimens" (PDF). National Park Service. November 2009. Retrieved 9 April 2017.
1 2 Horton, Diana. "Herbaria and Specimens: What Are They?" . Retrieved 9 April 2017.
↑ "Spirit Collection". Kew Royal Botanic Gardens. Retrieved 25 April 2019.
↑ "Care and Conservation of Botanical Specimens" (PDF). Care and Conservation of Botanical Specimens. ICON.
↑ "Conserve O Gram Volume 11 Issue 12: Preparing And Storing Herbarium Specimens" (PDF). National Park Service.
↑ Tremain, David. "Agent of Deterioration: Water". Canadian Conservation Institute. Canadian Conservation Institute.
↑ "Care and conservation of botanical specimens" (PDF). The Institute of Conservation (Icon) and Natural Sciences Collections Association (NatSCA). 2013. Retrieved 9 April 2017.
↑ Bedford, David J. (1999). "Vascular plants" (PDF). Retrieved 9 April 2017.
↑ "Appendix T: Curatorial Care of Biological Collections" (PDF). National Park Service. 2005. Retrieved 14 April 2017.
↑ "Collections Management Policy". National Museum of Natural History . Smithsonian.
↑ "Care and conservation of botanical spec" (PDF). ICON. Retrieved 25 April 2019.
↑ "Herbaria & Specimens". University of Iowa.

External links

This page is based on this Wikipedia article
Text is available under the CC BY-SA 4.0 license; additional terms may apply.
Images, videos and audio are available under their respective licenses.

[What_is_a_herbarium-1] "What Does the Herbarium Do?". Brown University . Retrieved 5 December 2023.

[2] "What is a herbarium". Royal Botanic Garden Edinburgh. Archived from the original on 6 March 2016. Retrieved 10 April 2017.

[What_is_an_herbarium-3] "What is an herbarium?". Brown University.

[Preserving_Plant_Specimens-4] 1 2 3 4 5 "Preserving Plant Specimens". The Royal Botanic Garden Sydney.

[:0-5] 1 2 "Conserve O Gram – Preparing and Storing Herbarium Specimens" (PDF). National Park Service. November 2009. Retrieved 9 April 2017.

[:2-6] 1 2 Horton, Diana. "Herbaria and Specimens: What Are They?" . Retrieved 9 April 2017.

[7] "Spirit Collection". Kew Royal Botanic Gardens. Retrieved 25 April 2019.

[8] "Care and Conservation of Botanical Specimens" (PDF). Care and Conservation of Botanical Specimens. ICON.

[9] "Conserve O Gram Volume 11 Issue 12: Preparing And Storing Herbarium Specimens" (PDF). National Park Service.

[10] Tremain, David. "Agent of Deterioration: Water". Canadian Conservation Institute. Canadian Conservation Institute.

[:1-11] "Care and conservation of botanical specimens" (PDF). The Institute of Conservation (Icon) and Natural Sciences Collections Association (NatSCA). 2013. Retrieved 9 April 2017.

[:3-12] Bedford, David J. (1999). "Vascular plants" (PDF). Retrieved 9 April 2017.

[:4-13] "Appendix T: Curatorial Care of Biological Collections" (PDF). National Park Service. 2005. Retrieved 14 April 2017.

[14] "Collections Management Policy". National Museum of Natural History . Smithsonian.

[15] "Care and conservation of botanical spec" (PDF). ICON. Retrieved 25 April 2019.

[16] "Herbaria & Specimens". University of Iowa.

[1]

[2]

[3]

[4]

[5]

[6]

[7]

[8]

[9]

[10]

[11]

[12]

[13]

[14]

[15]

[16]

v t e Cultural heritage and historic preservation
Topics and issues	Agents of deterioration Archival processing Archaeological science Archaeology Archive Bioarchaeology Calendar (archives) Conservation and restoration of cultural property Conservation and restoration of immovable cultural property Conservation and restoration of movable cultural property Conservation science (cultural property) Collecting Collection (museum) Collection catalog Collections maintenance Collections management Collections management system Cultural heritage Cultural heritage management Cultural property Cultural property documentation Cultural property exhibition Cultural property imaging Cultural property storage Cultural resources management Database preservation Deaccessioning (museum) Digital library Digital photograph restoration Digital preservation Disaster preparedness (cultural property) Film preservation Finding aid Fonds Found in collection Heritage asset Heritage science Inherent vice Intangible cultural heritage Integrated pest management (cultural property) Inventory (library and archive) Inventory (museum) Media preservation Midden Mold control and prevention (library and archive) Museum Optical media preservation Preservation (library and archive) Preservation metadata Preservation survey Provenance Repatriation Ruins Sustainable preservation Treasure Web archiving
Roles and expertise	Archivist Art dealer Art handler Auctioneer Collection manager Conservator-restorer Conservation scientist Conservation technician Curator Exhibition designer Mount maker Objects conservator Paintings conservator Photograph conservator Preservationist Registrar (cultural property) Textile conservator
Methods and techniques	Aging (artwork) Anastylosis Arrested decay Cradling (paintings) Cultural property radiography Detachment of wall paintings Desmet method Display case Digital repository audit method based on risk assessment Historic paint analysis Inpainting Kintsugi Leafcasting Lining of paintings Mass deacidification Overpainting Paleo-inspiration Paper splitting Reconstruction (architecture) Rissverklebung Textile stabilization Transfer of panel paintings UVC-based preservation VisualAudio
Conservation and restoration of immovable cultural property by item type	Archaeological sites Frescos Heritage railways Historic gardens Outdoor artworks Outdoor bronze objects Outdoor murals
Conservation and restoration of movable cultural property by item type	Aircraft Ancient Greek pottery Bone, horn, and antler objects Books, manuscripts, documents and ephemera Ceramic objects Clocks Copper-based objects Feathers Film Flags and banners Fur objects Glass objects Herbaria Human remains Illuminated manuscripts Insect specimens Iron and steel objects Ivory objects Judaica Lacquerware Leather objects Lighthouses Metals Musical instruments Neon objects New media art Paintings Painting frames Panel paintings Papyrus Parchment Performance art Photographs Photographic plates Plastic objects Rail vehicles Road vehicles Shipwreck artifacts Silver objects South Asian household shrines Stained glass Taxidermy Textiles Tibetan thangkas Time-based media art Totem poles Vinyl discs Woodblock prints Wooden artifacts Wooden furniture
Intangible cultural heritage preservation	Ancient music Applied folklore Dance notation Early music Endangered language Ethnochoreology Ethnomusicology Ethnopoetics Family folklore Folklore Folk art Folk dance Folk etymology Folk instrument Folk medicine Folk music Folk process Folk play Foodways Folklore studies Heritage language Heritage language learning Indigenous intellectual property Indigenous culture Indigenous language Language death Language preservation Language revitalization Living history Oral history preservation Preservation of meaning Primitive music Tradition preservation Traditional knowledge
Notable projects	Conservation issues of Pompeii and Herculaneum Conservation-restoration of Ecce Homo by Elías García Martínez Conservation-restoration of The Gross Clinic by Thomas Eakins Conservation-restoration of Leonardo da Vinci's The Last Supper Pompeian frescoes Conservation-restoration of the Shroud of Turin Conservation-restoration of the Sistine Chapel frescoes Conservation-restoration of the Statue of Liberty Conservation-restoration of the H.L. Hunley Conservation response to flood of Arno, Florence Modern and Contemporary Art Research Initiative Preservation Metadata: Implementation Strategies