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Field press: a corrugated cardboard box (bottom approximately 45 cm x 30 cm is best), cut so sides fold nicely over bottom, newspaper sheets cut to size, rope to close it.
Drying press: 2 plywood or lattice boards (45 cm x 30 cm), 2 webbing belts or ropes with slip-knots, corrugated cardboard sheets, sponge (carpet underfelt), blotter sheets, newspaper; plants will be sandwiched between newspaper, blotters, and then cardboard sheets. |
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3.1 When to Collect
Dry, sunny weather is best in terms of getting plants dried easily, but if that is not possible, a drier of some sort is recommended. The faster the plants are dried, the better they will look, especially in terms of colour and lack of mould, although care must be taken not to overheat the press. Press plants as soon as possible after collection; using a field press will provide better specimens than if they are collected in plastic bags and pressed later.
3.2 What to Collect
For herbaceous plants always collect at least part of the root system, stems, leaves, and, if possible, the flowers and/or fruit, and seeds. For woody plants collect a small stem and/or a piece of the bark (in addition to leaves, flowering and/or fruiting structures). Large fruit or succulent stems may be split or cut into pieces for drying or placed in separate folded paper (e.g. cones) if too large and juicy to be pressed. Note that some plants, e.g. willows, have separate sexes, both of which must be collected with flowers to identify them with certainty. |
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3.3 Pressing Plants
Clean all soil from roots (rinse off mud, then brush when dry). Arrange your plant
specimen on the newspaper carefully, so that it looks as natural as possible,
without too many parts overlapping each other (this will slow the drying process
and look ugly). Prune if necessary. Arrange tall plants by folding the stem like an
upside-down V, N or M. Turn at least one leaf upside down so the undersurface
can be seen when pressed. Leave room for a 7 cm x 18 cm label at the lower
right hand corner. Sandwich herbs between two blotters and then two cardboard
sheets. For thicker specimens use a sponge sheet in place of one of the blotters
to press around the thick stem or root and still flatten the leaves. When the
“sandwiches” of collected herbs are ready to press, stack them and place the
stack between the two plywood or lattice boards. Tighten the belts around the
press by standing on the press as you pull on the ends of the belts. Further
tightening will be necessary later as the specimens dry and shrink. Drying can be
done at room temperature or over a couple of heat lamps, but take care not to
overheat the press which would discolour the plants. |
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4.1 Sheets
Arrange the plants carefully with a minimum of overlap on the herbarium page (acid-free mounting paper). Attach the specimen to the mounting paper with thin ribbons of glue running from the paper across the plant part to the paper. The glue should not cover any parts necessary for identification, for example, the nodes and ligules of grass.
4.2 Voucher specimen label
Labels for the dry specimens can be prepared before the plants are identified, recording information known at that time. The genus/species and identifier can be added in later. Using a standardized label ensures that all necessary data are transcribed from the field book to the label accurately and efficiently.
A picture is worth a thousand words either as a photo or a sketch, although not a replacement for good field notes. If a picture is taken it is a good idea to note the roll number and exposure number.
Always number your specimens consecutively! It doesn’t matter if you collect the same species a hundred times on different occasions, each collection should have a separate number. Only multiple specimens of the same plant collected at the same time and place can share a single collection number.
Last but not least
Store the herbarium pages in a dry and dark place (it may be a good idea to store them together with the retention samples of the product being shipped). To avoid insect damage, the herbarium pages may be frozen at -20°C for 48 hours and checked on regularly. For every plant you are collecting, prepare a new voucher specimen every 5 years. |
Adopted from Marles, R. 2003 How to collect plants, draft and BC Ministry of Forestry, 1996, Techniques and Procedures for Collecting, Preserving, Processing and Storing Botanical Specimens, Forestry Division Service Branch |
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