Preparation of Plant (cactus) Specimens

[kadakuda]

When making botanical specimens what MUST there be? what are the rules exactly?

i assume there should be a rib section, areole, cross section and flower.

what about roots? fruit? seeds? should there be both whole and cross-section (flowers & roots)?

Should one voucher be of only one plant? this one seems like it obviously should be.

How does one dry and preserve these things, especially seen as how thick and juicy cacti cross sections would be.....use formalin solution?

many also seem to have a scale...is metric (cm/mm) standard?

photos are good? what about notes? it would seem to me that things like stamens would be very quickly damages, so would notes on these be useful? or do you want to keep the thing clean and clear of written stuff? what about slides (pollen)?

this pic has me thinking, it seems pretty rough.....is this how it is all done?

http://www.shaman-australis.com/forum/inde...ost&id=6985

any info would be good

also found this link

http://www.flmnh.ufl.edu/herbarium/voucher.htm

edit: also found this link that is nice, have not finished reading it yet.

http://ilmbwww.gov.bc.ca/risc/pubs/tebiodi...cherb/index.htm

Edited July 14, 2008 by kadakuda

[Teotzlcoatl]

How about keeping things like flowers in alcohol??? or something of the sort...

Whenever I've dried cactus flowers they don't look anything like the actual living flower... they curl up into a ball... no details can really be seen at all...

Looks like Friedrich & Rowley just dried those peices of cactus in the sun, I dry peices like that all the time.

Edited July 14, 2008 by Teotz'

[MORG]

Whenever I've dried cactus flowers they don't look anything like the actual living flower... they curl up into a ball... no details can really be seen at all...

You could press and dry the flowers like any other herbarium voucher. Most of the details on a voucher's floral material are viewed under a dissecting miscroscope or at least with a hand lens.

Vouchers should always be of only one species. Include all the information you can think of! The more the better. Cacti are a tricky one, I've only ever pressed leafy things that compact down relatively flat. I'm not too sure about how you'd go about "pressing" the limb of a big columnar cactus. You can dry fruits and seeds and attach them in a zip-lock bag to the herbarium sheet. Teotz suggestion of alcohol preservation is also good for fruit.

[kadakuda]

yes, cacti is where i get a little confused as well.....with various arthropds formaline is used to fix them, but it can mess up the dna and make things brittle......can it be used to fix the plant cells as well?

i guess it could also destroy chemicals, or leech them out, if using solvents.....which may screw up possible tests on activity, dna etc....

do people who make and deposit herbarium vouchers jsut press and dry plant material when fresh and use nothing chemical?

i think cross sections are easy enough to dry in a press, but i am still curious about larger sections like a cross that is an inch thick...or a fruit or a Hylocereus or Trichocereus.....????

where does one often place extra notes on a voucher? i know with animals if it is separate and attached by staple or tape or something, its credibility is ALWAYS in question...is this the same in the plant world?

would those paper baggies (glossene or however you spell it) be best? i would think plastic is the worst!

[Micromegas]

Hey, I recently did a prac at the state herbarium at the Adelaide Botanic Gardens where we were looking at their voucher specimens. One of the specimens was a stapelia of some kind that had been found out in the bush (weed from dumping of rubbish i think). They had pressed flowers, and for the succulent stem they had just cut a few cross sections to make thin little stars which had dried out quite well. I imagine you could do the same for a cactus, obviously the thinner the better, but even a few cms should dry out ok if you wanted to keep spines/areoles. They have vouchers from all types of weeds at the herbarium I assume they must have dried and made specimens of opuntias too. All the vouchers were in a manilla folder, nothing in jars/alcohols etc. as far as i could tell, in boxes in rows and rows of shelves. As for information, for some plants there was next to none, for others there was quite a bit, specimens seemed to just be pressed and dried without chemicals, although the whole building was heavily guarded against bugs. For specimens with fleshy fruits there were dehydrated fruits. I didn't see any roots, just foliage for the most part, and flowers. I only looked at representative samples however, wish I could tell you more, but for a cactus a few cross/star sections and a dried and pressed flower would have seemed acceptable, with as much info collected as possible.

Micro

[MORG]

yes, cacti is where i get a little confused as well.....with various arthropds formaline is used to fix them, but it can mess up the dna and make things brittle......can it be used to fix the plant cells as well?

Use ethanol. Colour doesn't fix as well as with formalin but DNA will be preserved fine. This is still done for fruit and other fleshy parts for which morphology needs to be preserved.

do people who make and deposit herbarium vouchers jsut press and dry plant material when fresh and use nothing chemical?

Yep. First step is to stick your labelled voucher between paper (newspaper will do) into a press (a whole lot of thick cardboard pieces with rigid metal 'bookends'. The ends are tied to each other with belts that can be tightened putting pressure on the specimens stuck between the cardboard sheets). Then this is dried at close to zero humidity at a reasonably high temp (35-40 degrees) for several days. Chemicals aren't used much any more, the vouchers are freeze dried further after the drying step (about -80 C I think?).

Specimens are then 'mounted' on archival paper resembling manilla folders (this may or may not involve a little bit of sticky tape type stuff to keep stray parts of the specimen on the paper, but it is not required. Herbarium specimens are always supposed to remain horizontal). Information on collector, locality, habitat and other notes is then printed on a label with the herbarium number and stuck onto the folder beside the mounted specimen.

i think cross sections are easy enough to dry in a press, but i am still curious about larger sections like a cross that is an inch thick...or a fruit or a Hylocereus or Trichocereus.....????

I've seen herbarium specimens of half a dried out Nelumbo nucifera flower head and they're thick! It's a bit odd but the specimens are kept in boxes stacked on top of each other, so just be careful of what you put on top of any weird shaped one I guess.

where does one often place extra notes on a voucher? i know with animals if it is separate and attached by staple or tape or something, its credibility is ALWAYS in question...is this the same in the plant world?

All collection info should be printed out on the specimen information card. The credibility of collector's notes is still always in question Any bozo can make a collection of one particular target species, accurately reading a GPS, identifying soil types, giving good directions and describing the surrounding floristic community is alot harder.

would those paper baggies (glossene or however you spell it) be best? i would think plastic is the worst!

I've seen dried fruits in small plastic bags, stapled to the herbarium sheet. Not ziplock bags though, don't know if its a special breathable plastic or something... no idea.

[George]

The times are a changing.

Why don’t they change those rules.

We don't use old exploding flash B&W cameras anymore so why all the dried stuff?

Take high quality photos of everything and scale them. You could keep tissue cryogenically frozen for DNA.

[kadakuda]

pictures are -ok-, but under the scope i just get all these damn dots

lol, but really, how can one truly ID a specie without a real one in front of them...even then its hard with most forms of life.

[whitewind]

Additional question (great thread, has most of what I need)

Does one also press half flowers so it is easy to see the internal structure?