Starting an Herbarium, Any Tips?

Nature Talk
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I am starting to press plants for an herbarium, and I have a few questions as I get started, and wanted to ask fellow naturalists who have done this before. Google has given me mediocre help so far, and I would like my herbarium to last as long as possible.

  • Can I laminate my leaves? Or does the heat involved damage them? I have leaves mounted on a sheet of paper and laminated that are eleven years old, and they look fine, but I am curious if it’s better for me to mount the specimens with glue/tape/something else.

  • That leads to my second question, if I do have to mount specimens some other way besides lamination for them to last as long as possible, don’t they crumble apart over time without anything covering them?

  • Any other tips? I know how to press leaves and what plants in my area are protected, I mostly need advice setting my herbarium up.

Thank in advance!

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hello, former herbarium technician and current PhD student working in a herbarium here. cheers to you for starting a proper herbarium collection of your specimens – all too rare to see these days!

  • I would recommend against laminating leaves. the gold standard for affixing specimens to sheets in all the herbaria I’ve worked with or visited (F, MO, MOR, IND, and so on) is archival-quality glue, supplemented with equally good-quality tape. some super old-school herbaria (e.g. IBUG) will fasten plants to the sheets using cotton string, in literally a needle-and-thread fashion. lamination is fine for education specimens or un-affixed leaves, but I have never seen it used at scale in any herbaria.
  • I have never seen specimens completely crumble apart over time, as long as a bit of precaution is taken. (I would still recommend against lamination.) herbaria maintain their plants on horizontal sheets, organized using folders, and store them in special filing cabinets. I’ve routinely handled specimens up to 150 years old without particular precautions, other than the normal care that you would want to handle sheets with – never turn them vertically, never bend them, never leave them in direct sunlight or keep them in areas with open food and drink. while fragments do come off sheets from time to time, those can also be placed in fragment packets that are usually also affixed 1 to a specimen sheet. I linked a place that they can be bought, but I have also cut and folded them myself out of archival-quality paper (100% cotton or equivalent). except for these sorts of small fragments, though, herbarium specimens don’t crumble over time as long as they are properly and fully dried, affixed firmly to the underlying sheet, and kept in good storage. avoid moisture at all costs – air-drying or low-heat drying while pressing is suitable. in fact, laminating leaves that aren’t fully dried would probably damage the specimen if there’s any water remaining in the tissues.
  • in terms of how to store your properly conserved specimens – if you aren’t in need of a full-on upright storage cabinet, I would recommend keeping your specimen sheets in a storage bin suitable for long-term use. plastic bins with anti-moisture gaskets can be bought for as little as a few dollars at retail stores (I have quite a few of them that are big enough for standard-sized herbarium sheets) and work well for this purpose.

I think that’s the main points, but feel free to ask anything more as always! all good questions here!

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Laminating is very unusual. For scientific work in the herbarium you usually want to see your specimen close up and from all sides. Means you want to be able to put them under your optical instruments and turn them, without any obstructing plastic layer in between.
For a serious scientific herbarium you better not laminate the sheets.

Two other points: proper collection data. Use the iNat app and record all your herbarium collections in the field while collecting. This will ensure high quality collection data (location, time, collector) keep the data always with your herbarium specimen. At least the iNat ID number should always be with the herbarium specimen … that way you keep the connection of the fotos and original data in iNat and the herbarium specimen.

Second: The more aspects and parts of the plant you collect, the more usefull will your herbarium be. Flowers, fruits, leaves upper and lower side, branches, bark, roots, seeds, seedlings all of these are interesting and useful. Make fotos and collect the whole plant if possible, or at least branches with several leaves and preferably flowers and/or fruit. Parts that are difficult to preserve or collect like moist fruit, thick bark and wood, can be photographed.

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These are both very helpful! Thank you! Is acid-free printer paper fine to mount plants on? I have acid free glue and tape already.

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Here is good information on linking your iNat obs to your herbarium specimens.

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anything acid-free is reasonable in that it won’t damage your collections, but printer paper is awfully thin to support the weight of a specimen. I am usually able to carry a herbarium sheet flat on the palm of a single hand — if it can be done without the corners of the specimen sheet sagging, or danger of anything bending and cracking, that’s good; if not it will require much more careful handling. I would also have to say that printer paper is very small for specimens if you mean the typical letter-sized dimensions.
if you actually mean a larger size printer paper, pardon me! but here’s how a letter sheet compares to the standard dimensions of a herbarium sheet:

image
image4032×3024 1.22 MB

these sheets aren’t super thick, but they’re more like paperboard than regular paper. they’re slightly flexible but stiff enough to help provide a bit more structure to the specimen when it’s affixed.

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Mounting: cloth book binding tape cut into thin strips and strong cotton/composite thread depending on application. Mount to ~300gsm sheets.
Storage: store sheets in individual paper folders inside boxes
Labeling: You probably already know this but a collection of specimens is useless without sufficient data.

This is an example of a specimen undergoing mounting at the W.A. Herbarium, a barcode and possibly more labels will be added later in the process.

IMG_20240305_114919
IMG_20240305_1149191920×2560 494 KB

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Hi @giannamaria,

When preparing specimens, it is best to choose fertile material, and aim to fill the space you have available. Very scant specimens are often missing critical parts needed for ID. The best way to press and dry is using gentle pressure. Overpressing specimens leads to artificial distortion. You want to have the specimen as 2D as possible to help it not crumble when you store others on top of it, but that is it.

If you’re using a plant press to dry specimens in, best practice is to dry each specimen in a sleeve of newspaper, with a layer of cardboard between sleeves. You can use two sleeves and change the outer one regularly until the specimen is dry, but don’t use excessive newspaper or the specimen may have trouble drying and go moldy.

We use heavy card stock for mounting in our herbarium, as it is stiff and provides support for the specimen, helping it to not crumble over time. Around each sheet goes a flimsy of regular paper to protect it. We use A3-sized card, so the flimsy is an A2 sheet folded in half. Acid free vs. not acid free is less of a requirement. Acid-free is best practice, but a lot of old specimens we have are not on acid-free paper and holding up OK. Keep in mind that plants have their own lignin and acidic substances that will cause decay over time in their tissue. The card you mount them on or paper outside will not change this. The paper may become brittle, but the plants will have their own decay rate. Light is the biggest killer, IMO.

The best glue for attaching specimens is PVA. It has decent archival qualities and will remain somewhat flexible over time, in case you ever need to detach a specimen for any reason (we do fairly regularly). If you do need to detach a specimen, you can cut PVA glue with a razor blade.

I would definitely not laminate. Plastics have awful archival qualities in the longer term. Your specimen will be artificially flattened and details such as the nature of the indumentum will be obscured. Reflections from the plastic will make photography more challenging.

Write abundant notes. Once the piece of plant is pressed and mounted, if you didn’t collect the whole plant, you have no way of knowing what the rest of the shrub or tree might have looked like. Describe it in your notes. Specimens of vascular plants always eventually fade to brown. Accurate notes on colour, particularly of flowers, are really useful.

The information I collect is:

  • What is it (taxon name)
  • Where did it come from?
  • Elevation?
  • When was it collected?
  • Who collected it?
  • What was the habitat?
  • What was the habit of the plant (describe the plant)?
  • Other notes (was it common? Was it collected for a specific purpose? Anything else you want to keep permanent record of…)

Finally, we organise our herbarium alphabetically by family, genus, species and infraspecies name.

I hope this helps!

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I’d also say this: look up your nearest Herbarium and ask them to show you around. We aren’t open to the public, but if someone comes to the door and is interested, I’ll give them a 5-minute tour and answer questions. We’ve developed long-term relationships with volunteers and collectors who just walked in none day asking what a Herbarium is…

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I once visited the herbarium in Lae, Papua New Guinea. They did not have funding to run to the air conditioning, and the whole herbarium smelled of rotting vegetable matter and fungal growth.

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looks up nervously from spreadsheet titled “New Guinea reconciliation”

I’ll be rocking in the corner, nervously whispering my mantra “there must be isotypes” if you need me.

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Real Botanists don’t mount their specimens; they just have several pieces of furniture filled with pressed plants in newspapers dating back to the Eisenhower administration.

Looking through my bookmarks, I have a few links that may be of use:
https://www.mobot.org/MOBOT/molib/fieldtechbook/welcome.shtml Ron Liesner’s notes for Missouri Botanical. Aimed in the general direction of tropical collectors, but has some useful advice on pressing and dealing with large or oddly-shaped specimens.

https://biosciences.unimelb.edu.au/engage/herbarium/teaching-resources Uni Melbourne guide to collecting. The PDF on “How to Make Your Own Herbarium Specimens” has some useful practical detail on using gummed (linen) tape.

https://www.floridamuseum.ufl.edu/herbarium/methods/specimen-preparation-guide/ UFL guide to mounting. Practical and pretty closely matches what was taught me at PH when I prepared my vouchers for accession there: gluing, followed by judicious reinforcement with linen strips and occasionally sewing down with awl and linen thread. Note the use of wax paper when stacking the glued specimens to dry, and always leave space for the label and a fragment packet.

Herbarium Supply LLC and University Products have been my go-tos for ordering stock materials.

I second the recommendation to visit a local herbarium and see how they do it–collections managers are often willing to train you in mounting technique if you will help out with the backlog of unmounted specimens bequeathed to the herbarium by Real Botanists, some of which are in newspapers printed with medial “s”. The people at MICH are lovely and I am sure they would receive you kindly.

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perhaps I should have said “in controlled conditions”. I’m also very concerned about some herbaria in Venezuela. tropical herbaria have it tougher even in ideal times, but any disruption to the buildings they’re housed in can be disastrous.

this is how I came to worry about those Venezuelan herbaria… I had hoped the world could avoid a repeat of something like the decimation of B, but some older workers didn’t designate types with many duplicates. I still wonder if I should even bother to put in a loan or scan request to LE these days for some holotypes with zero duplicates that are apparently held there alone.

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I’ll add to the chorus of people suggesting you visit a good herbarium. Last week, I got to participate in a work day at the New England Botanical Club herbarium and get a tour of the Farwell Herbarium, both at Harvard University in Cambridge, Massachusetts, in the US. I was impressed with the enormous amount of work and care that goes into taking care of specimens that had been donated to the collections. Even if you are collecting only for your own personal herbarium, please do it properly, because one day you (or your heirs) may want to donate that collection to a museum herbarium.

And while you’re at it, start a digital database for your specimens, too. It may seem like a pain to keep up a database in the beginning, but if you’re still collecting five or ten years from now, it’s wonderful to be able to look things up quickly, rather than having to sort through physical specimens.

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i think a big question is why you want to make a collection and also who it’s for. if it’s just for you on the scale of a few decades, honestly, you can press your plants almost any way, and it should work just fine as long as they are dry and bug free.

if you want to do it for science, if you have an herbarium near you, it might make sense to volunteer there to see how the professionals do it and contribute your efforts to that. there are lots of herbaria that shut down because they lose funding or people. sometimes collections can be absorbed by larger, more well-funded collections, but many are not that lucky.

i’ve seen laminated specimens which have lasted at least 30 years, with just yellowing of the plastic, as long as the underlying specimen was pressed properly. these are generally intended to be shared and handled by the general public and are not the primary collection.

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What would you recommend for that? Just an excel file?

Mostly for my own enjoyment, but I do want to make it properly incase I don’t want it anymore. That way, I can donate it instead of just throwing it away, which I feel would be a waste.

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I use an Excel spreadsheet for my bryophyte specimens I collect, but other botanists use fancier database programs. I don’t know which database programs, though. I use Excel because it’s simple and learning how to ID mosses and liverworts is hard enough!

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Have you considered volunteering for an existing herbarium? They’re usually in need of people to process and mount existing specimens, as well as collecting target species. They’ll likely train you on the correct way to collect, record, process, and mount specimens, too (harder than it looks - I used to grade uni student class collections and there were some real doozies). I know because I was an undergrad research assistant, and met many older volunteers who did that just as a way to help! I think it would be a great way to maximize your impact, versus just having a private collection that isn’t accessible by botanists and may not have the species they’re interested in.

As a bonus, you can sometimes start a little private collection with surplus specimens you and others have mounted. I still have an Armeria maritima I mounted for a Botany class 10 years ago.

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just to set expectations, i haven’t heard of many cases of herbaria accepting material from individuals, unless they were significant collections in some way. (each specimen would need to be bug treated, reviewed, relabeled, scanned, stored, and input to their database, and it’s often not worth it for what’s there.)

unfortunately, there are lot of small private collections that just get lost and deteriorate after the original collectors lose interest or pass on.

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For what it’s worth, I’m an individual who just donated specimens, so maybe it depends on the herbarium? I would certainly ask long before you donate the specimens; the herbarium may or may not want specimens mounted, for example.

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