Mounting herbarium pressed specimens for the herbarium is hard work and takes practice - but a good specimen can be scientifically important and look cool, too!
What is a herbarium? It’s a collection of pressed and dried plant specimens for scientific study. These can be used to study things like where species are found, how distributions have changed over time, and how plants are related to each other. There’s a lot that goes into making a good herbarium specimen, including a good label - I’ll cover that in a different post!Â
Ideally a specimen will have reproductive structures important for identification, such as flowers, fruits, cones, or, in the case of a fern like this Dryopteris marginalis, spores. It’s good to include roots, too, even though these can be a little hard to get sometimes. It may even be necessary to collect multiple specimens from the same plant at different times of year to make a proper identification.
The specimen must be pressed (preferably using a herbarium press, which is basically newspaper between blotting paper and cardboard in a simple wooden frame. If you’re doing it for fun, you can use newspaper between sheets of cardboard under a few books) and dried (with a herbarium dryer if possible - this is like a big heated metal cabinet). It’s important to get the specimen in the press as soon as possible so it doesn’t wilt! I prefer to keep mine in the press for one day outside of the dryer and then open it up and rearrange the partially pressed plants the next day so I can fix any leaves that got accidentally folded. The fewer folded leaves, the better! It’s much easier to fix leaves this way than once they’re all dry and crispy. Then once all the leaves are fixed, and at least one is turned backwards, I close up the press again and put them in the dryer.Â
After drying, plants that are being kept in herbaria should be frozen in a -80 degree C freezer to kill off any pests that might destroy plants in the herbarium. And then, once the plants are completely identified and labels have been printed and affixed to the mounting paper, you can mount them!Â
The easiest way to mount most plants is to take a little bottle of herbarium glue (you can use watered-down Elmer’s glue if you’re just doing this for fun at home) and put little spots of glue directly onto the plant, blot off any extra, and then just stick it to the page. Be super careful not to cover up the label! You can always use a razor blade to cut off pieces of the plant that would cover the label or go off the edges of the paper, but be sure to do this before you put the glue on. The back of the plant doesn’t have to be entirely covered in glue - just enough so it doesn’t flap or peel off easily. If possible, make sure that the reproductive structures are visible and at least one leaf is turned backward and at least one is turned forward so you can see both sides of the leaves. Then put a sheet of wax paper over it, a piece of cardboard, and maybe a sheet of thin foam if you’re worried about crushing anything. Finally, you can lay down a couple of fairly light books on top of the cardboard if you think a little pressure is needed to hold the plant in place. It should be all set within a day!
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