tree-logo.gif (7741 bytes) Plant Taxonomy (BIOL308)  -  Stephen G. Saupe, Ph.D.; Biology Department, College of St. Benedict/St. John's University, Collegeville, MN 56321; ssaupe@csbsju.edu; http://www.employees.csbsju.edu/ssaupe/

THE HERBARIUM

I. A Plant Morgue
    An herbarium is a collection of pressed, dried, and labeled plants (and may also include other types of collections including wood or seeds). Perhaps a less morbid analogy is that an herbarium is a reference library of plants. It is generally agreed that Luca Ghini (1490-1556), Professor of Botany at the University of Bologna, prepared the first herbarium specimens as we recognize them today. His students, Cibo, Turner, Aldrovandi and Cesalpino also made herbaria, some of which still exist (John McNeill, 1997; Taxacom Discussion). Another contender for the oldest herbarium specimen is an olive branch removed from King Tut’s tomb (Craig Hilton-Taylor, 1997; Taxacom discussion).

II. Value of Herbarium Specimens

  1. Monetary Value. Herbarium specimens can be considered priceless (since they are irreplaceable) or nearly worthless ("if you've seen one redwood you've seen 'em all" - R. Reagan). Various groups have calculated the approximate value of herbarium specimens. These calculations are typically based on the value of the collector’s time, the value of the curator and staff time, the cost of electricity, paper, glue and other supplies and other costs inherent in storing the collection. These calculations typically result in values that range from $3 - 6.00 per specimen (Sue Thompson, Carnegie Museum) to $10 (American Systematics Collections) to $52.50 (see Armstrong, 1992). Whatever the figure, none take into account the intrinsic scientific value of the specimen.
     
  2. Scientific Value. The information content of a herbarium is tremendous. Herbarium specimens document: (a) the appearance of a plant in a particular locality at a particular time of year; (b) the range of variation within a species; (c) the nature of evolutionary processes; and (d) when a particular plant flowers or fruits (phenology). They also (e) provide material for study away from the field or at another season. And, they serve as: (f) vouchers, or voucher specimens, that document the identity of plants used in taxonomic, chemical (i.e., DNA), or cytological (i.e., chromosome counts), or other studies, and as and (g) type specimens - specimens upon which names are based. Finally, (h) herbarium specimens may have a wealth of information about the medicinal or food or utility of the plant (Siri von Reis Altschul, 1977).

III. Herbaria around the world
    The number of specimens in different herbaria varies from just a few to millions. The CSB/SJU Biology Department herbarium has approximately 28,000 specimens (an estimate - you are welcome to count yourself - one bonus point for an accurate count). Large herbaria include (# specimens in parentheses): Museum of Natural History, Paris (8.8 million); Royal Botanical Gardens, Kew (7 million); Komarov Botanical Institute, Leningrad (5+ million); NY Botanical Garden (5.3 million); Harvard (combined herbaria, 4.8 million); US National Herbarium (4.4 million), Smithsonian (4.1 million); Field Museum of Chicago (2.4 million) (data from Index Herbariorum). The University of Minnesota has over 800,000 specimens.

    Index Herbariorum lists the world’s herbaria, size, types of collections and a wealth of other information. This excellent resource is now on-line (see references). Each herbarium is given a standard acronym. CSB is the acronym for our herbarium.  Index Herbariorum is now available on-line.

IV. Specimen Arrangement in the herbarium
    Specimens are typically filed by family in a phylogenetic sequence based on a classification system. The Engler- Prantl system is commonly used in many North American herbaria. Cronquist's system is popular with more recently-arranged herbaria. Within a family, genera are alphabetical, and ditto for species in a genus. Specimens may be sorted by geographic region within these categories. Dalla Torre and Harms provided numbers for each family and genus based on the Engler Prantl system (see Jones and Luchsinger).  In contrast, a few herbaria file collections alphabetically, again by family.

    There are advantages and disadvantages to each method: 

What do you think?

V. How to find specimens in the herbarium
    This depends upon how the herbarium is arranged. We will discuss finding specimens in our herbarium, which is arranged by Cronquist's system (1991).

VI. Handling herbarium specimens
   
When handling herbarium specimens you must do it very carefully because they are very FRAGILE and VALUABLE!   When handling:

    Some Do's and Don't for handling specimens follows:

DO
  • pick up the specimen with two hands, one hand holding an edge and the other under the specimen to provide support.
  • place the specimen on a table or work surface for study
  • lift up a stack of specimens and set it elsewhere to get to a specimen in the middle of the stack
  • place specimens on a sheet of cardboard or other solid surface when transporting them
  • handle specimens one at a time
  • place specimens face up in a pile

DON'T

  • turn the specimens in a folder like pages in a book.
  • hold a specimen with one hand while trying to examine parts.
  • place books or other materials on top of specimens
  • squeeze a folder
  • slide specimens into or out of folders
  • turn specimens upside down or bend, twist, fold, spindle or mutilate
  • carry specimens or folders on edge always hold specimens flat (horizontal) with the specimen side up.

VII. Annotating herbarium specimens
     If a specimen is misidentified, a small annotation label is usually affixed to the specimen indicating your opinion of the correct name, your name and the date.

VIII. Pest Control
     (a) freezing (common technique used in many herbaria); (b) repellents (like para-dichlorobenzene); (c) fumigants; (d) microwave.

IX. Loans and Exchanges - discussed in class

X. Studying Herbarium Specimens
    Material should not be removed from a specimen without the permission of the herbarium curator. When studying specimens, first use material in any packets that accompany the specimens. Only small fragments should be used. Return unused material to the packet with the specimen.

    To rehydrate and soften a dry specimen, apply 10% glycerin in water or boil the specimen in water to which is added a few drops of detergent or simply add a few drops of warm soapy water. Most identifications by professional botanists are done on dried herbarium specimens. However, it is easier to study fresh specimens if they are available. If possible, save some fresh material to do your identifications.

    After identification is complete, place any unused/leftover material in the specimen packet.

XI. Web sites:

XII. References:

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Last updated:  09/14/2007 / Copyright by SG Saupe