Section of Botany - Mounting Guildelines

CMNH - Section of Botany

~Plant Mounting Guidelines~

by Meg Burroughs

Plant specimens ready to be mounted have been; pressed, dried, identified, frozen and are accompanied by labels containing their collection data (See plant collecting guidelines). Typically, plants arrive from the collector in newsprint, in bundles secured, with a species cover and tied.

Plants are mounted to eleven and one half by sixteen and one half inch archival herbarium paper for support and to facilitate handling and preservation. The museum uses water-based white adhesive glue. This type of glue is completely reversible and cost effective.

The mounting process begins with the label, which is always glued fully to the bottom right corner of the herbarium sheet. Any annotation labels are glued fully when possible and placed directly above the collection data label. The upper right corner is reserved for the museum name and the plant accession number. These two restricted areas often limit plant placement and fitting of the specimen or specimens in the limited space. Plant placement is facilitated with the use of a mock herbarium sheet that can be used over and over again so as to prevent the archival paper from being soiled. A mock herbarium sheet may be made from a species cover cut to sixteen and one half by eleven and one half inches with the restricted areas blocked out. This allows work such as trimming, soil removal and finding the best angle for vegetative, floral or fruit part(s) before the final gluing (photo).

Displaying all aspects of the plant is important (photo). Care must be taken to represent the variety of features present such as leaf size, leaf shape and leaf arrangement. As far as possible make sure each specimen shows the range of flowered and/or fruit stages present. Flowers should face front and back when possible as well as fruits, or placed in a packet. Reproductive parts also need be shown and at least one leaf should be turned over to view the under-side. Roots are also a key to identification and often need to have dirt brushed away with natural bristle brushes used just for that purpose. Any seeds or loose plant fragments are placed in a folded paper packet and glued to the sheet, most often in the upper left area. At times, small zip-lock bags are used to contain tiny parts and are used inside packets, which come in various sizes. Large fruits are filed separately which is indicated on the main label. A common cafeteria tray is used to hold the adhesive, which is about the same size as a herbarium sheet and will accommodate most plants. The glue is spread on a tray with a natural bristle brush to cover the surface and diluted with as little water as possible to obtain the best mixture suited for each type of plant.

First the label is glued in place, then the plant is put directly in the glue and leaves and stems are gently pressed with a tool to make sure they have contact with the adhesive (photo). The plant is lifted from the glue with tweezers (forcepts) and placed on the herbarium sheet in its predetermined arrangement (photo). Paper towels blot any excess glue and a sheet of waxed paper is added to protect the upper surface. A corrugate (pressing cardboard) is added to cushion between layers and aid in drying. The process then begins again with the next herbarium sheet.

Various types of weights are used to press the mounted specimens until dry (photo). Large weights press a stack of newly mounted specimens, while various sized loosely filled sandbags are used on top of the waxed paper when an individual specimen is both bulky and flat. Small flat metal weights, covered in a plastic tape to prevent rust, are also used.

After overnight drying the stacking process is reversed. Any weights used are removed along with the cardboard and the waxed paper. Both the cardboard and waxed paper can be reversed. Each dry specimen is then looked at carefully. If any repair is needed it is put aside and then filed back into the bundle after repairs are made. Plants are placed back into a species cover, gently tied and put in the freezer for several days to assure they are contamination free (photo).

Strapping is done by volunteers and is the last step in the mounting process (photo). During strapping, adhesive is drawn across parts of the specimens at intervals to hold loose stems or leaves.. Also dots of glue are used on edges of leaves or stems to assure firm attachment.

A final freezer placement for several days is made before they are added to the database and then filed into the already 600,000 specimens in the permanent collection.