The HERBARIUM*

Section A. Herbarium in General

I. HERBARIUM: CONCEPT AND DEFINITION

The term herbarium, used in the strictest sense today, is simply a collection of dried specimens. Lawrence (1951) and others include in their definitions the arrangement of specimens in the sequence of an accepted classification and are available for reference or other scientific study. "Herbarium" used in its original sense, however, referred not to a collection of plants, but to a book about medicinal plants. Tournefort in about 1700 used the term as an equivalent to hortus siccus (Stearn, 1957), and this use was taken up by Linnaeus who also adopted it as a substitute for hortus siccus, hortus mortus, and others. It was largely through his influence that it superseded the former terms.
The procedure of pressing and drying specimens for storage has been an amazingly successful one in terms of preservation of detail and specimen longevity, and the plants so preserved provide a concrete basis for past, present and future studies. In its more than four-hundred-year history the .herbarium has become an institution. Today one associates the term herbarium not only with preserved plant specimens but also with certain botanical activities. The herbarium is the basic reference source of the taxonomist and has become a center for research as well as teaching and public information.
An herbarium, a special kind of museum, can also be regarded as a data bank with vast quantities of raw data. Each specimen has information content and therefore value which will, of course, vary depending on completeness of specimen and data and the source of the material. Each specimen has information about the vegetation of an area, a population, and the taxon to which it belongs (Rollins, 1965). The collection, therefore, represents a source of primary information about man's explorations and observations of the earth's vegetation, and document the results of much the past inquiry into the nature and relationships of plants. Herbarium specimens are now used for studies in the disci[plines which were probably never even dreamed of at the time early collections were made and herbaria organized. These studies include such fields as cytogeography, biochemical systematics, palynology, and genecology.

II. HISTORICAL DEVELOPMENT

The beginning of the herbarium as a collection of dried specimens affixed to paper for a lasting record is attributed to Luca Ghini (1490?-1556). According to Arber (1938) Ghini seems to have been the sole initiator of the art of herbarium-making and this art was disseminated over Europe by his students. Gherards Cibo, a pupil of Ghini, began collecting and preserving specimens as early as 1532 and his herbarium is extant today. John Falconer, an Englishman, is mentioned as possessing an herbarium in the writings of Lusitanus in 1553 and William Turner in 1569, and it is believed that he also learned of herbarium making either directly or indirectly from Ghini (Arber, 1938). Although the herbarium technique was a well-known botanical practice at the time of Linnaeus, he departed from the convention of the day (mounting specimens and binding them into volumes) by mounting his specimens on single sheets and storing them horizontally much as is the practice today (Stearn, 1957; Dewolf, 1968). Although this method became general during the second half of the 18th century, perhaps, as Stearn (1957) believes, due to Linnaeus' example and teaching, it was by no means universal. In fact as late as 1833 Asa Gray was offering bound volumes of grasses and sedges for sale (Dewolf, 1968). In the United States several herbaria are known to have existed in the mid 1700's. Many of these and later ones found their way to Europe, where they are preserved. According to Lanjouw and Stafleu 1964) and Shetler (1969) the oldest institutional herbarium in the United States is that of Salem College started in 1772. Other early institutions include the Academy of Natural Science in Philadelphia, Amherst College, Boston Society of Natural History, Charleston Museum, and others, all founded before 1860 (Jones and Meadows, 1948).
In addition to changes in mounting, early workers also began depositing specimens in established collections, as well as exchanging specimens. It is indeed fortunate for botanists of today that such practices developed so early. Many herbaria have been destroyed by fire, insects, war and ignorance, and all that remains are duplicates sent to other institutions on exchange. An unfortunate policy was the scanty field notes made by early collectors and the lack of concern for original labels as early herbarium specimens were exchanged, sold, etc. For an interesting account of the sale, transfer, and handling of several early private North American herbaria, see Stuckey (1971).

III. PRESENT SIZE AND STATE OF HERBARIA

Herbaria range from small personal collections (mostly of a few hundred specimens with a few notable exceptions) to large collections of colleges, universities, private foundations and governmental agencies involving millions of specimens. In 1964 ten herbaria reported collections in excess of three million specimens (Lanjouw and Stafleu, 1964; Shetler, 1969). Table 31-1 lists the five largest herbaria in the world and the eight herbaria in the United States with one million or more specimens.

Shetler (1969) estimates that the herbarium resources of the world may include as many as 250 million specimens, although the total number actually reported by the various institutions was 148 million. Of this estimate 78 million are in European collections and 36 million are in North America. The difficulty is, of course, the number of private and small public herbaria which often do not report their holdings or whose holdings are not generally accessible.
Today collections are more accessible than ever before due to the efforts of many individuals, and national and international organizations. Two extremely useful indices for locating collections are Index Herbariorum by Landouw and Stafleu (1965), which includes location and curators of herbaria of the world, size and type of collection, type of institution, publications (serials) and important historical collections and Index Xylariorum (Stern (1967), an index to wood collections of the world. The principal wood collections of the United States include those of the Arnold Arboretum (Aw), Cambridge, Massachusetts; Rancho Santa Ana Botanic Garden (RSAw), Claremont, California; U. S. Forest Products Laboratory (MADw,SJRw), Madison, Wisconsin and Smithsonian Institution (USw), Washington, D. C. A current project underway which should also be of tremendous aid to systematists is the "Type Registry" being compiled by the Smithsonian Institution . Various herbaria, particularly those with an abundance of type material and other historic collections, often issue accounts of their collections; e.g., The Sloane Herbarium in the British Museum (Dandy, 1958), Herbaria of the Department of Botany in the University of Oxford (Clokie, 1964), and Linnean Herbaria (Stearn, 1957).

IV. THE CHANGING NATURE OF THE HERBARIUM AND ITS FUTURE

The nature of the herbarium as an institution and collection remained essentially unchanged until about fifty years ago. Developments in genetics, biochemistry, cytology, ecology, and other fields leading to less descriptive and more experimental work have been largely responsible for the changes that have occurred, but unfortunately there has been some resistance to this change. The herbarium, while it serves its former goals as a center for documentation, a source of information for monographs and floristic works, and as a resource in education and other fields, has the opportunity and the responsibility to expand to meet the needs of the future. Most systematists now use numerous approaches to problem solving, and the herbarium should remain as the central facility, as indeed it is in many institutions.
The status, operational aspects, and future of herbaria have recently been reviewed by Beaman (1965) and Shetler (1969). Rollins (1965) has also pointed out some of the roles of the herbarium in research and teaching. Shetler (1969) has cast some doubt on the future of the herbarium as a scientific institution and resource. It seems desirable that herbarium goals and practices be reviewed, particularly in the light of the recent developments in taxonomy and botany in general. Each herbarium administrator, staff member, and all those who use the herbarium should consider the herbarium's role not only at their institution but also on the international scene, and guidelines should be set up to insure maximum availability of information in herbaria both at present and in the future. Turrill (1964) has stated that there are two sets of problems facing herbaria--one is how herbaria can be maintained within reasonable limits., and two, how they can be improved. Some of his suggestions include the division of herbaria into special and general types. Special herbaria would include local ones (those devoted to a given area and serving local interests), special research herbaria (e.g., cytological and cytogenetic vouchers), ecologic herbaria including not only specimens but photographs, field notes, schemes of ecological analysis). Admittedly the general herbarium presents additional and more difficult problems, and Turrill (1964) proposed the limiting of such herbaria in number with each having some specialization; e.g., systematic or regional. He further summarized the purposes of a general herbarium as follows:

"(1) to provide facilities for determination on any material, including new taxa; (2) to enable new monographs and floras to be prepared; (3) to preserve specimens of historic importance, such as those dating discoveries, introductions, and increases or restrictions of ranges; (4) to assemble data for working out ranges and ecological distributions; (5) to bring together in a relatively permanent form specimens for comparative morphological or phylogenetic studies and to provide material for special researches, as in plant anatomy and palynology." For an interesting account of the relevance of national, regional and local herbaria see Conquist (1968), Brenan (1968), and McNeil (1968).

"to foster care, management, preservation and improvement of systematics collections and to facilitate their utilization in science and society by:

1. Providing representation for institutions housing systematics collections;
2. Encouraging direct interaction among those concerned with systematics collections and their use;
3. Providing a forum for consideration of mutual problems;
4. Promoting the role of systematics collections in research, education, and public service through:
   
   1. the coordination of information concerning needs of users,
   2. the planning of advisory services,
   3. the development and implementation of national goals and priorities;
5. Other means and devices which shall be determined from time to time by the membership" (Association of Systematics Collections, 1972: 1).

At the time this association was formed at a Systematics Biology Symposium held in July, 1972, by the Smithsonian Institution in collaboration with the National Academy of Sciences, six reports were presented by a Committee of the Conference of Directors of Systematics Collections. The six reports and related materials, including considerable input from the symposium participants, were considered by a writing committee of twenty-five systematics and administrators who met to plan for the coordinated management of national systematics resources.

This committee in their prepublication draft of America's Systematics Collections: A National Plan, compiled and edited by H. S. Irwin, W. W. Payne, D. M. Bates and P. S. Humphrey (1973) presents a "statement of the primary goals of the systematics collections community," and a "description of the specific goals of the systematics collections community with respect to improving the condition of the collections and the services they provide;" a "discussion of systematics in science and society today" and "of the problems affecting the systematics community:" a list of "specific recommendations (The National Plan) that will move to resolve the problems and enable the systematics collections community to realize its goals" and a "statement of priorities and estimated costs of implementing them." The primary goals of the systematics collections community are "to improve the condition of systematics collections as a National resource" and "to improve the efficiency of services associated with systematics collections resources. Specific goals and specific service-related goals include:

"
1. Management of the specimen inventory and associated documentation to insure: (a) permanent conservation of the specimens themselves; (b) ready access to them and their documentation; and (c) space, facilities, and library resources enabling systematists to improve the information content of the collections through identification, classification, and elaboration of the intrinsic information carried by each specimen.
2. Addition of new specimens and associated information that: (a) reflect the goals and priorities of science and applied science; and (b) improve the quality and quantity of specimen and taxon related data, so that the information load of each specimen is enhanced.
3. To make available nonproprietary, specimen-or taxon- related information in a variety of useful configurations.
4. To enable incorporation of specimens and associated data in the information management system.
5. To enable ready access to the specimens themselves, and to associated documentation and library materials."

The National Plan includes the following recommendations which, when implemented, should solve many of the problems of systematics collections.

"
1. Support and strengthen an organization dedicated to improving the condition of systematics collections and their services.
2. Establish a series of Councils to study specific problems relating to systematics collections.
3. Establish Advisory Committees representing those elements of the scientific community concerned with systematics collections.
4. Identify systematics collections of importance as national resources and designate National Resource Centers.
5. Develop standards for systematics collections: physical facilities, collection storage, preservation, specimen and data acquisition and documentation, collection growth, inter-institutional loans.
6. Implement electronic data processing in collection management procedures.
7. Develop technical training programs for professional service personnel and establish mechanisms for personnel placement.
8. Develop mechanisms whereby the resources of systematics collections can be used more effectively in studying and resolving problems affecting the quality of the environment and develop programs for improving public awareness of the importance of correct identification of species to indicate environmental changes and their effects on human welfare.
9. Improve the services and other contributions of systematics collections to graduate education in systematic botany.
10. Address the problems of libraries and publications associated with systematics collections.
11. Develop and implement programs for improving public awareness and use of systematics collections as a national resource important to science and to the solution of problems affecting human welfare.
12. Study financial resources available and potentially available to the systematics collections community and seek means to implement priorities..."

Section B. PROCESSING AND ACCESSIONING OF SPECIMENS

I. THE SPECIMEN

Traditionally the typical herbarium specimen has been a vascular plant affixed to a 11 1/2 inch x 16 1/2 inch sheet, but recent developments necessitate a change in the concept of herbarium specimens. Wood samples, fossils, pollen and spores, microslides, liquid-preserved materials, photographs, drawings should be considered as specimens and therefore as part of the herbarium. These changes require new housing facilities and record keeping, as well as cross referencing and retrieval systems. Today most herbarium curators are urging collectors to make a concerted effort to make their collections as complete as possible by including material for chromosome counts, wood samples, pollen slides, pollinators (or at least observational records), associated species and detailed habitat data. Weeds and cultivated species are at last being considered worthy of inclusion in the collections. If the herbarium is to be the source of information and documentation it should be, the materials used in biosystematic studies (e.g., natural and artificial hybrids, mass collections, etc.) as well as other types of studies should be included in the herbarium. Biosystematists and others should confer with directors and curators concerning the handling of materials.

II. SOURCES OF MATERIALS

The influx of material into a herbarium is usually from the following sources:

1. Staff and Student Collections. These vary according to staff research, interests, speciality, and herbarium goals. Collections may be for floristic, monographic, biosystematic, or taximetric studies. Staff and students at institutions which have no herbarium or only teaching or reference collections, may choose to document their studies by sending specimens to other institutions. These specimens may be sent either as gifts or loans and published works should always include the name of the herbarium where vouchers are deposited.
2. Exchange. Duplicates or special collections are exchanged among various institutions, usually on a one-for-one basis. This is one of the major means of adding to a collection and an efficient means of getting needed materials at minimal costs to all concerned.
3. Gifts. These are variously interpreted in different herbara. Some treat receipt of all specimens other than exchange or loans as gifts while others include only those for which no staff services are required. These may range from an entire herbarium to a few specimens sent to a staff specialist.
4. Loans. Loans are generally either temporary (short term; e.g., a study of specific taxa for preparation of a monograph) or indefinite (permanent; e.g., the loan of an entire herbarium from one institution to another). The latter is a particularly desirable procedure for historic and other collections which may be for the most part inaccessible to most botanists or where proper housing facilities are lacking. These can often be loaned to another institution and still have the original name maintained.
5. Purchases. The purchase of an herbarium is an uncommon event today. Usually private or institutional herbaria are donated or are deposited on permanent loan at an institution. Most purchases today involve collections from specific areas (particularly the tropics) with prices ranging from ten cents to over one dollar per sheet. In some cases an institution may help to sponsor a collecting trip in exchange for a set of specimens.
6. Identification Service. In most herbaria specialists are willing to determine specimens for other workers and interested amateurs. Some herbaria have staff members whose specific job is service identifications. In general the specimens sent for identification are kept by receiving institutions unless other arrangements are made in advance. These specimens should be of such quality that they are desirable as specimens (see chapter 18 on collecting), and should not be sent without some prior agreement. Requests for identification services should be reasonable in terms of the time required and number of specimens to be identified.

III. HANDLING OF INCOMING SPECIMENS

Regardless of the source most materials are first unpacked and variously treated to rid them of insect pests which are a serious threat to specimen longevity. Such pests include the larvae of cigarette and carpet beetles, moths, booklice and silverfish. Procedures vary, but several methods are commonplace:

1. Fumigation. This involves the use of such compounds as methyl bromide, carbon bisulphide, carbon tetrachloride, ethylene dichloride, hydrocyanic gas, lindane, dichlorvos stripe, or paradichlorobenzene. While it is necessary to treat all new additions and loans upon arrival, the entire collection should be treated on a regular basis. (see section C--Herbarium Use, Operation and Maintenance). Several drawbacks to fumigation given by Fosberg and Sachet (1965) are:
   1. Commonly used fumigants are also harmful to humans.
   2. Many fumigants are inflammable.
   3. Insect eggs and pupae are often not killed unless fumigation is done in a vacuum chamber.
2. Heating. The use of specially constructed chambers with heating elements which can keep specimens at 44 degrees C for some hours is an effective method. While this is a good method for new acquisitions, it is usually not practical in most cases for treating entire collections (for details and references see Fosberg and Sachet, 1965).
3. Poisoning. There are several methods of treating specimens making them either permanently poisonous or unpalatable to herbarium pests. Specimens may be poisoned by dipping or painting them with an alcoholic solution of mercuric chloride. Specimens so treated should always be clearly labelled since this compound is extremely poisonous. It is also said to make some paper brittle and crumbly, blacken labels, and attack aluminum.

IV. ACCESSIONING OF COLLECTIONS

Accessioning is defined by Fosberg and Sachet (1965) as the recording of the receipt and origin of lots of specimens coming into the herbarium. Each lot is assigned an accession number. The minimum data that is recorded is name of sender, date of receipt, type of transaction (gift, exchange, purchase), number of sheets, place (country, province, etc.), and kinds of plants (algae, fungi, vascular plants, etc.). Space may be left to record the inclusive sheet numbers after the specimens are mounted (Fosberg and Sachet, 1965). Other systems used include the registration of each specimen (mostly abandoned but for an example see Millspaugh, 1925) or simply mounting specimens and assigning sheet numbers. . A practical and efficient way is to stamp sheets with the official herbarium seal and number them before specimens are mounted. Since exchange, loan, and gift records are kept as well as all correspondence, the separate accession record may be considered unnecessary. Sheet numbers, in addition to being used to assess growth and efficiency in herbarium operations, have importance directly related to taxonomic research. They are an ideal means of referring to a particular specimen in a collection. The exclusive use of collectors' numbers may not be sufficient, particularly in designating types.

V. SPECIMEN PREPARATION

Mounting procedures vary but at present only a few methods are popular. It cannot be emphasized enough that the mounting procedure is a critical step in specimen preparation. A carelessly mounted specimen can be essentially useless. Mounting, like pressing, is indeed an art.

1. Strapping. A specimen is placed on mounting paper and the label pasted squarely in the lower right-hand corner. Strips of linen tape (gummed cloth or Holland cloth) are moistened and placed around stems, across leaves, etc. until the specimen is firmly attached to paper. (Cellulose or plastic tapes which deteriorate or soften with age or which decompose when specimens are fumigated should not be used.) Care should be taken so that important details are not covered by the strips. Length and width of strips depend on the part to be secured. Another method of strapping or stripping (as it is often called) involves the use of liquid plastic. This method, the Archer Method, uses a mixture of ethyl-cellulose and Dow resin in toulene and methanol, prepared according to the schedule of Rollins (1955) given below.
   

   Toulene	880 cc.
   Methanol	220 cc.
   Ethocel	10 cps. standard
   Dow resin	75 gms.

   Toulene and methanol are mixed first and the resin added and dissolved completely. The ethocel is added slowly and stirred until partly dissolved. The solution should be allowed to stand 24 hours before using. Store in airtight containers and use a 4:1 mixture of toulene and methanol as a solvent. The plastic is usually dispensed from a pistol-grip pressure oil can or a polyethylene (mustard or catsup) squeeze bottle. 2. Pasting or Gluing. Specimens are often attached to their sheets by gluing. An efficient and effective way is to coat the surface of a glass or copper plate with glue (use a paint brush), place the specimen on the plate, and tap gently with forceps or cards. The specimen is then lifted, using forceps, inspected to check distribution of glue, and then placed on the sheet. If the glue is not evenly distributed, more may be applied using a soft brush. Tap specimens down gently using relatively lint-free tissue. Labels generally are applied using the same glue and put on before the specimen. If any glue is on the exposed surface, the sheet may be covered with waxed paper. This is a particularly good procedure for grasses and sedges. All fragments, fruits, and seeds should be placed in packets or envelopes and these affixed to the herbarium sheets at this time. In cases where the materials are too bulky, the packet should be numbered with an herbarium accession number and/or the collector's number and set aside to be mounted later. The specimen is then covered with a sheet of newspaper (usually the one containing the specimen, if not too dirty) and placed in a stacking box or simply placed on the table. Specimens are so stacked until 20 to 25 specimens are in a stack. A board and weight are then placed on the stack. If mounting is slow the weight should be applied sooner. Stacks should be allowed to dry for 24 hours.

   The papers are then removed and specimens are ready for the next step. Several glues or pastes are available. The "Special A Tin Paste" is used in some herbaria, but library pastes such as "IPI" or glues such as "Elmers", " Nicobond," or "Wilhold" are also used. Some herbaria use the Archer formula (plastic) for gluing specimens to the sheet. The plastic, dispensed from a "squeeze" bottle or pressure gun, is applied to the back of a specimen and material is placed on the sheet, weighed with washers or other suitable weights and the plastic allowed to dry. All of these glues, but not the plastic, are water soluble.

2. Sewing. Except where strapping is the only process, most specimens, after gluing, are strapped in some manner--linen tape, liquid plastic, white glue, and/or sewing with a heavy linen thread. A very efficient process combines sewing and strapping (with glue or Archers). Sewing is restricted to heavy stems, overlapping leaves, rhizomes, matted bases of grasses, large fruits, cones or heads, or other places where the use of plastic or glue is impossible or impractical. Threads on the back of sheets should be covered with linen or paper tape. Specimens are placed on a sheet of cardboard and strapped. Each specimen is then stacked one upon the other using 4-5 wooden blocks to separate each specimen. This requires little work space and allows proper ventilation.
3. Special Handling. One case of special handling is the use of serial sheets for a single specimen, long a necessity in tropical areas. Although several techniques are used and much depends on the notes of the collector, the series of sheets should bear a single accession number and an annotation noting on each sheet the number of sheets in the series; e.g., sheet 1 of 5. Such a series is much more desirable than the practice of insisting that regardless of size, an entire plant should be on a sheet even though critical examination of the material is impossible.

Inflorescences of Typha, Cirsium, etc. often shatter and may be held intact by enclosing them in bags (cheese cloth or netting). Bulky fruits, cones, etc. may be removed and stored in special boxes or cases. Specimens should clearly indicate that both sheets and accessory materials are present in the collection.

Each sheet should also be stamped with the distinctive seal and/or name of the herbarium. The use of letters (abbreviations) only should be avoided (e.g., specimens marked OU Herbarium may mean University of Oxford, Oregon, Oklahoma, etc.) Some herbaria use a stamp with the name of the institution and its official abbreviation (see Lanjouw and Stafleu, 1964; Fosberg and Sachet, 1965).

Proper mounting depends greatly on careful collecting. Suggestions for collecting and pressing of herbarium specimens are given in Chapter 18.

VI. SORTING AND FILING OF SPECIMENS

Once the specimens have been glued, sewn and/or strapped and allowed to dry (in the cases where glue and/or plastic are used), they should be sorted for filing. Techniques and physical arrangements vary, but ultimately specimens are sorted to family, genus, species, and infraspecific taxa. If geographic provinces are recognized in the collection, additional sorting is required. Regardless of the filing system used, specimens should be arranged in the order they will occur in the herbarium. Considerable time and energy can be saved if this procedure is followed. In some collections, once the specimens are sorted, they are routed to curators of special groups for checking and/or filing.

Specimens are filed on shelves in herbarium cases in 24 x 16 1/2 inch folders called genus covers. These heavy manilla or bristol folders are often color coded. Specimens are either filed directly in these folders or in a thinner species folder. Today there seems to be a breakdown in terminology for folders. The genus cover often in reality serves as a species folder if the representation of a species warrants an entire folder.

In small collections the commercial "genus cover" may serve as a family folder. Specimens are placed in folders face up with labels in the lower righthand corner. The genus name usually appears in the lower lefthand corner on the face of the cover. Specific names or alphabetical sequence appear in the lower righthand corner. Names may be printed or stamped on the folder or on a label which is then glued to the cover.

VII. ARRANGEMENT OF SPECIMENS IN THE HERBARIUM

1. The General Collection. Although there are numerous possible systems of arrangement of specimens, the schemes most often encountered are given below:
   1. Bentham and Hooker. This system is rarely used in the United States. See Franks (1965) for a list of larger European herbaria using this system.
   2. Dalla Torre and Harms numerical arrangement of the Englerian System. A common system in the United States and other countries although it is often modified so that only family sequence is followed with genera and species being alphabetically arranged. (See Dalla Torre, C. G. de and H. Harms, 1900-1907).
   3. Besseyan System. This system became popular in the 1920's and is still used in some herbaria (particularly those organized after the above date).
   4. Alphabetical. This system varies from strictly alphabetical (by family, then genus, species, etc.) to some modified system (e.g., segregation of ferns, gymnosperms, monocotyledons, dicotyledons, with alphabetical arrangement of families in each of these groups).
   In addition to these basic systems, many herbaria also employ a geographic arrangement. Local areas are in one color folder, with U.S., other New World countries, Old World, etc. in other colors. Such schemes range from few geographic categories to quite elaborate ones. These divisions are exceedingly useful for floristic studies. Even though colored folders are more expensive and fading colors occasionally are confusing, the reduction of handling of all specimens of a species to examine only those specimens from a particular area (e.g., county, state, or physiographic province) may justify the added cost.

   Undetermined materials ( of which every herbarium has its fair share) are generally filed at the end of genus or family and are usually in specially marked folders (e.g.," undet".). In addition to specimens and special materials (discussed below) non-plant materials are often of great value and are included in general collections. These include photographs (e.g., a type specimen, a habitat), drawings, correspondence concerning a specimen, keys, notes on synonomy and cross-reference markers ("dummy" sheet or cover).

2. Special Collections. In addition to general collection, many herbaria maintain various special collections.
   1. Type Collection. Type specimens such as holotypes, isotypes, co-types, are often housed separately from the general collection, where unnecessary handling an risk of damage can be greatly reduced. These are commonly filed in the same sequence as the general collection, or alphabetically. Another solution is to place types in the general collection, but in specially and conspicuously marked genus covers.
   2. Synoptic Collection (Teaching or identification). Special collections for routine identifications and student use are sometimes separated from general collections. The synoptic collection can greatly reduce time spent consulting specimens in a herbarium as well as specimen wear. These collections are usually small and may be arranged and rearranged (particularly for teaching purposes) according to recent schemes of classification; e.g., Cronquist, Thorne, Hutchinson, etc.
   3. Special Research Collection. Mass collections, artificial hybrids, as well as pollen and spores, anatomical preparations and bud materials may often be housed separately or in special folders or cabinets. If this is the case, some notation in the form of a dummy sheet or annotation should be made in the general collection so that the existence of these materials can be readily known by those consulting the herbarium. The arrangement of such systems varies according to the type of materials and inclination of the curators. Alphabetical, community, numerical (according to accession number) or phylogenetic systems are commonly used. Where the system differs from that of the general collection it should be clearly explained in the "Herbarium Guide" (see section C)
   4. Historical Collection. Many earlier collections, as mentioned above, were bound in volumes and these are often not amenable to inclusion in general collections. Other collections include those loans or gifts with specification that they are to be maintained as separate entities. The only other reason for separate housing is for protection. Some prefer to include these materials in the general collection in special folders, as mentioned earlier concerning types. In fact many group types and other historical materials (including letters, notes, etc.) into one special collection. Regardless of physical arrangements, a catalog of materials and their arrangement should be included in the "Herbarium Guide" and/or appropriate "dummies" inserted into the general collection.

Section C. HERBARIUM USE, OPERATION AND MAINTENANCE

I. HERBARIUM USE

Herbaria exist only for use regardless of type of collection--research, identification (synoptic), teaching, or other. Every effort for maximum efficiency in locating material in a collection (information retrieval) should be made without endangering the collection.

1. Herbarium Guide. Every herbarium should have a printed guide to the collection. This guide should explain the systematic and geographic arrangement; color code of folders; list of families with numbers and case number (including segregate and combined families; e.g., Ericaceae vs. Pyrolaceae, Monotropaceae); map of case arrangement; color code of folders, list, location and arrangement of special collections; and a generic catalog. The guide should also contain herbarium policy statements concerning reshelving of materials, handling of specimens, use of equipment and other facilities, loan procedures, and other pertinent information. Such guides can save considerable time on the part of visitors as well as the herbarium staff.
2. Specimen Use. Specimens are preserved for use but should be handled with extreme care since they are of scientific value and generally irreplaceable. The following suggestions are to aid users in handling specimens properly.
   1. Keep sheets flat, do not suffle or leaf through a folder like a book. Specimens are brittle and easily damaged.
   2. Store properly. Preferably, specimens should be stored in herbarium cases or at least on shelves. Do not crowd too many specimens into a box or "pigeon hole." Keep materials in covers when not in use.
   3. Do not lay books or other heavy objects on specimens.
   4. Place loose fragments in packets or envelopes if the specimen to which the fragment belongs can be ascertained.
   5. Use materials sparingly. It is often necessary to dissect flowers or fruits. Use no more than is required and place all fragments in a fragment envelope on the sheets. For dissection, flowers and fruits may be softened by boiling or treating with a softening or wetting agent. Pohl's softening agent (Pohl, 1965) is an excellent wetting material and may be prepared according to the following formula:

      1% solid "Aerosol OT"	1.6 ml 75% aqueous "Aerosol OT"
      74% distilled water	73.4 ml distilled water
      25% methyl alcohol	25 ml methyl alcohol

      This solution will not stain or discolor sheets but is best used in a watch glass. Place materials to be softened in a watch glass and add several drops of the solution. Many materials are sufficiently softened in a few minutes. Fragments may be blotted dry and returned to the fragment envelope.
   6. Use a long-armed dissecting microscope. An entire specimen can be studied with this instrument without bending the sheet.
   7. Support the specimens with a ventilator or other stiff board when carrying specimens, even for short distances
   8. Call to the attention of curators those specimens in need of repair.
   9. Do not write on the herbaium sheet unless permission to do so has been given by someone in charge.
   10. Reshelve specimens only with permission and always with extreme care.
   11. For additional information on annotations, borrowing specimens etc., see Section C ID (Loans).
3. Visitors. Visiting an herbarium is, of course, one of the best possible ways to study material. An investigator can examine the exact materials desired as well as searching "undetermined" folders, consult types and other special collections (some not available on loan), and use the library and botanic garden as well as exchange ideas with fellow botanists. Visitors would do well to follow common courtesy if they wish to have access to collections, particularly at unusual hours, such as evenings, weekends, or holidays. A note in advance can mean the difference in having, or not having, a comfortable place to work, and access to a microscope, as well as gaining admittance to special collections and libraries.
4. Loans. Most herbaria lend materials to other institutions (rarely to individuals). Reciprocal agreements between many institutions often result in transit costs only one way. One should, however, be sure that such agreements exist before requesting a loan. For the most part loans should be requested after some preliminary work has been done so that unduly long-term loans are avoided (loan periods are generally for six months). Requests should be for reasonable amounts of material and for specific taxa rather than communities or floristic provinces. Loans should be requested by the curator or director of the herbarium for study by a specific person, and should be addressed to the director or curator of the lending instiution. Special permission should be obtained if fragments, pollen, or other materials are to be removed. Even with permission the utmost discretion should be exercised. Many herbaria ask that duplicate slides, chromatograms, and other preparations made from their material be included when the specimens are returned. When in doubt, the borrower should consult the curator of the lending institution for specific instructions. A commonly accepted procedure is that all specimens be annotated whether they are used in ecological, floristic, monographic, anatomical, biosystematic, or other studies. This should include even those specimens determined correctly. A convenient way to agree is by using an exclamation point (!) followed by the name of the investigator and date (at least the year). Printed annotation labels affixed above the original label are the most desirable. The original label should not be altered. Some institutions allow the use of a rubber stamp with small, yet readable print (preferably using black ink); e.g.,"Examined in a survey of parasitic angiosperms of Southwestern U.S., John Doe, 1971." The name of thwe institution where work is being conducted is also quite desirable. Annotations should reflect the history of use of an individual specimen. Materials should be returned promptly on the date due or an extension should be requested. Most institutions honor requests as soon as staff resources permit and at considerable time and expense. Loan forms to be returned are generally sent out before or at the time the loans are shipped. Upon receipt of a loan, the borrower should examine, count and acknowledge the shipment. Any damage occurring in transit due to mishandling or insects should be noted on the loan acknowledgment form. Each sheet should be checked for the stamp of the lending institution. Since sheets may have the seal of more than one institution, careful notes should be made, particularly if the borrower has material from several institutions. Specimens were packed by the lender in a certain order and an effort should be made to return them the same way.

   Borrowed materials should be housed in "fireproof," dust- and pest-free cases. Materials may be fumigated and repellents used provided they do not damage specimens, labels, and photographs. Great care should be used in all cases. Plastic strapping is softened by strong fumigants and repellents such as paradichorobenzene. This and other information is often included on loan forms. Most specimens are sent "library rate" by parcel post at considerable savings to all; however, the lending institution determines the mode of transit and this should be followed unless permission to do otherwise is obtained.

   In addition to the annotations, the borrower can perform many other services:

   1. Determining duplication.
   2. Supplying additional data (obtained from duplicates from other institutions).
   3. Correcting locality data (by annotation).
   4. Pointing out mixed labels.
   5. Determining specimens as to type--isotype, paratype, etc.
   6. Indicating a mixed collection.
   In most cases both parties should profit from a loan.

II. OPERATION AND MAINTENANCE

An herbarium, contrary to the opinion of some, requires constant attention if materials, information and facilities sought by botanists and others are to be available and in proper condition.

1. Specimen Care.
   1. Backlog of materials. Keeping up with the influx of materials is probably one of the greatest problems in most herbaria. This is often due to lack of support, staff and space, and to inefficiency. Where possible, backlogs, which in turn create storage and fumigation problems and consequently endanger specimens, are to be avoided. Inaccessible materials are of no value.
   2. Specimen repair. This is an endless problem. Specimens in need of repair and remounting should receive prompt attention as soon as they are noted. Some institutions repair all material before it is loaned or before reshelving it after it has been used. If staff resources permit, repairs should be made as they are noted by persons filing new acquisitions, inserting new genus covers, etc.
   3. Fumigation. As mentioned earlier (section B) fumigation (or other means of protection) of the entire collection is a necessity in most if not all herbaria. Annual fumigation may not be sufficient to insure a collection against damage, particularly if all new accessions are not first fumigated. Constant alertness is mandatory. Those cases housing members of the Asteraceae, Brassicaceae, Ranunculaceae and Apiaceae should be scrutinized often since members of these families are commonly attacked by herbarium pests. Visitors would be of great service by calling to the attention of curators signs of insect damage. Fumigation of a collection may be done by a commercial firm or by the herbarium staff. The entire collection may be fumigated at one time or only part of it. The method used will, or course, vary depending upon physical arrangement and size of the collection, financing, and staff preferences. A 3:1 mixture of ethylene dichloride and carbon tetrachloride is a commonly used fumigant which is placed in each case and the case then sealed. This solution is dangerous and should be used with extreme care. Stern et al (1969) and Lellinger (1972) have discussed the advantages and disadvantages of using lindane and dichlorvos as fumigants and repellants. Lellinger (1972) indicated that dichlorvos ("no Pest" or "Vapona") is probably the safer material when used as a fumigant rather than a repellant. This treatment involves placing one 0.25 strip/22.3 ft. 3 of case space for 7-10 days with the case remaining closed. This treatment should be used twice each year asuming all incoming materials are fumigated before insention and that there is no infestation.Curators should consult both the Stern, et al. and Lellinger papers before using this method. Initial fumigation of small lots of specimens, e.g., new accessions or loans, may be carried out in specially constructed cabinets or chambers. Methyl bromide is the fumigant often used in this operation.
2. Insertion of Materials (other than new accessions).
   1. Genus covers. As collections grow new species and/or genus covers must be added. Division of material into smaller groups (systematic or geographic) results in easier access and reduction in needless handling.
   2. Dummy folders. As a result of changes in nomenclature and taxonomic revision materials may in time be lost unless some precautions are taken. The problem can be easily solved by inserting a dummy folder in the appropriate place in the herbarium; e.g., Hymenoxys (see Tetraneuris); Calylophus serrulatus (see Oenothera serrulata). These may also be used to refer to additions to special collections.-wood samples, cones, types. Temporary dummies are useful for indicating materials on loan or being repaired.
   3. Photographs, Drawings, Maps, etc. These may be mounted on sheets or placed in envelopes and are usually treated as specimens. Care should be taken to make sure such materials will not be damaged in the course of regular fumigation.
3. Supplies and Equipment. All equipment, including herbarium cases, should be checked and cleaned carefully. In addition to having a clean and attractive place conducive to work as well as functional equipment, many of the sources of insect infestation, dust catchers and fire traps are eliminated. Supplies for mounting, repairs, labels, genus covers, etc. must be inventoried and ordered. Fortunately mounting paper (100% rag) is used in sufficient quantities that it is usually readily available from paper companies and biological supply houses. In fact, some paper companies issue special catalogs and supply lists for herbarium supplies--mounting paper, genus covers, paste, glue, etc. Most herbaria maintain a file on sources of supplies.
4. Correspondence and Record Keeping. (See also Fosberg and Sachet, 1965). All records and correspondence concerning exchanges, loans, gifts, and accessions should be kept and filed. Methods vary, but correspondence is often filed alphabetically according to person or institution. Exchange records are commonly entered in a ledger or journal or in a special card file. Information recorded usually includes date, number of specimens received or sent, origin of material, and balance. Duplicate or triplicate exchange forms are usually sent with an exchange lot and the receiving institution acknowledges receipt of shipment, verifies specimen count and condition, and account balance. One copy is returned to the sender as a record. Loan forms generally are similar to exchange forms. In fact, many herbaria use the same form and simply check the appropriate type of transaction. Loan agreements should be read carefully for they may specify conditions under which specimens should be housed, type of annotation required, etc. Information of considerable importance concerning specimens, types, etc. may be in herbarium correspondence which should be preserved. Fosberg and Sachet (1965) suggest binding letters from one person or institution in chronologically arranged volumes.
5. Annual Report. The preparation of an annual report can be exceedingly profitable for herbaria of numerous kinds and sizes. It not only provides an opportunity to reflect on progress and shortcomings of the past year but is useful in planning for future growth and development. Such reports usually include summaries of various accounts and records; e.g., loans and exchanges, special requests, and gifts. These reports also often include information not available from account ledgers and journals and which consequently may be of historical and other importance; e.g., research in progress, field trip reports, library and herbarium requisitions, new equipment purchases, staff changes, and development of new techniques and procedures. This information may be useful in preparing grant proposals and annual budgets and supplying information to various administrators and botanical institutions. For examples of detailed reports see director's annual report in current volumes of Aliso and Arnoldia.

Section D. HERBARIUM GLOSSARY

(Largely adapted from Fosberg and Sachet, 1965)

HERBARIUM LITERATURE

• Arber, A. 1938. Herbals, Their Origin and Evolution, 2nd ed. University Press, Cambridge.
• Archer, W. A. New plastic aid in mounting herbarium specimens. Rhodora 52: 298-199.
• Beaman, J. H. 1965. The present status and operational aspects of university herbaria. Taxon 14:127-133
• Brenan, J. P. M. 1968. The relevance of the national herbaria to modern taxinomic research [in Great Britain]. In: Modern Methods in Plant Taxonomy. V. H. Heywood (ed). Botanical Society of British Isles and Linnean Society. Academic Press. London.
• Clokie, H. N. 1964. An Account of the Herbaria of the Department of Botany in University of Oxford. Oxford University Press, London.
• Cronquist, A. 1968. The relevance of the national herbaria to modern taxonomic research in the United States. In: Modern Methods in Plant Taxonomy. V. H. Heywood (ed.). Botanical Society of British Isles and Linnean Society. Academic Press. London.
• Dalla Torre, C. G., and H. Harms. 1900-1907. Genera Siphogamarum ad systema Englerianum conscripts. Leipzig.
• Dandy, J. E., editor & compiler. 1958. The Sloane Herbarium. British Museum (Natural History),London.
• Davis, P. H., and V. H. Heywood. 1963. Principles of Angiosperm Taxonomy. D. van Nostrand Company, Inc., New York
• DeWolf, Gordon P., Jr. 1968. Notes on making an herbarium. Arnoldia 28:69-111.
• Fosberg, F. Raymond, and Marie-Helene Sachet. Manual for tropical herbaria. Regnum Vegetabile 39:5-132.
• Fosberg, F. R., and M. Sachet. 1965. Manual for tropical herbaria. Regum Vegetabile 39: 5-132
• Franks, J. W. 1965. A Guide to Herbarium Practice. Handbook for Museum Curators, Part E, Sec. 3. The Museums Association, London.
• Irwin, H. O., W. Payne. D. Bates. & P. Humphrey (compilers & editors). 1973. America's Systematics Collections: A National Plan (Prepublication Draft).
• Jones, G. N., and E. Meadows. 1948. Principal institutional herbaria of the United States. American Midland Naturalist 40:724-740.
• Lanjouw, J., and F. A. Stafleu. 1964. Index Herbariorum. Part 1. The herbaria of the world. 5th ed. Regnum Vegetabile 31:1-251.
• Lawrence, G. H. M. 1951. Taxonomy of Vascular Plants. The Macmillan Company, New York.
• Lellinger, D. B. 1972. Dichlorvos and lindane as herbarium insecticides. Taxon 21: 91-95.
• Lundell, C. L., and R. Kirkham. 1966. A methof of applying Mystox (lauryl pentachlorphenate) to protect mounted herbarium specimens. Wroghtia 3: 1-7-180.
• Millspaugh, C. F. 1925. Herbarium organization. Field Mus. Tech. Ser. 1(3): 1-18.
• McNeill, J. 1968. Regional and local herbaria. IN: Modern Methods in Plant Taxonomy. V. H. Heywood (ed.). Botanical Society of British Isles and Linnean Society. Academic Press. London.
• Pohl, R. W. 1965. Dissecting equipment and materials for the study of minute plant structures. Rhodora 67: 96-96.
• Porter, C. L. 1959. Taxonomy of Flowering Plants. W. H. Freeman and Co., San Francisco.
• Rollins, R. C. 1955. The Archer method for mounting herbarium specimens. Rhodora 57:294-299.
• Rollins, R. C. 1965. The role of the university herbarium in research and teaching. Taxon 14:115-120.
• Shetler, Stanwyn G. 1969. The herbarium: past, present and future. Proc. Biol. Soc. Wash. 86:687-758.
• Smith, D. E., Jr. 1971. Preparing herbarium specimens of vascular plants. Agriculture Information Bulletin No. 348. Superintendent of Documents. Washington D.C.
• Stearn, W. T. 1957. An introduction to the "Species Plantarum" and cognate botanical works of Carl Linnaeus. Prefixed to the Ray Society facsimile of Linnaeus's Species Plantarum, 1, London.
• Stearn, W. T. 1971. Sources of information about botanic gardens and herbaria. Biol. J. Linn. Soc. 3:225-233.
• Stern, W. L. 1967. Index Xylariorum. Regnum Vegetabile 49, Utrecht.
• Stucky, R. L. 1971. The first public auction of an American herbarium including an account of the fate of the Baldwin, Collins, and Rafinesque herbaria. Taxon 20: 443-459.
• Turrill, W. B. 1964. Plant taxonomy, phytogeography and plant ecology. Vistas in Botany IV:187-224.