Due to lack of interest, this post has been relegated to a spot below ;)

I don't know what is the answer but you could perhaps look to see what some the online herbariums may have as rubus examples. I know there are some online but I haven't looked for them in a while so google would have to help you out there.

Anything on preparing samples for herbariums or just "pressing flowers" would help you with sample prep techniques.

If you do find some good resources, please do share. :)

FataMorgana

I'd say that it isn't lack of interest, it's probably lack of information - there doesn't seem to be much, as you note.

I took a class this summer that wanted a 'vouchered list' of the area we were studying, i.e. we had to have pressed specimens to back up the species on the list. (This is a cheap way to get scientific data for a preserve run by a non profit!) At that, we didn't get much information about the actual preperation of specimens; the main thing he said was that the ID characteristics should be present in the specimen, in other words we needed to check Gleason and Cronquist (the most comprehensive plant manual covering NJ - although we did look at some others) and see what characters they used in their key and try to include those in the specimens.

Unfortunately, in the case of Rubus, that means just about everything. Sounds like it would be best to try to get the whole plant, preferably in bloom (assuming you know for sure that it's a Blackberry and not a Raspberry, for which you do need the fruit). Our teacher said if we needed more than one sheet to use the same label on all of them and mark them 'Sheet 1 of 3' for example.
He suggested visiting the herbariums he was donating the material to but I don't think any of us did; I think if he does it again that might be a field trip. Also, I run across pictures of pressed herbarium specimens on line these days when I'm looking to ID stuff; you could probably pull up some examples of what other people did with Rubus.

If the stem is really thick you might put a couple extra layers of cardboard or newspaper over the leaves so they press flat even though the stem sticks up farther. If the stems are really long and pretty similar along their length you probably don't need the whole stem, but it looks like rooting tips are a pretty important characteristic so you'd want to include a cane tip to show if that's true or not.

If you know where you're going to send it for ID you could contact them and ask them. We were told the herbariums getting our specimens didn't want them mounted, they preferred them loose in a fold of paper with the label included.

Hope this helps.

WW

Thank you WW and fatmorgana. I'm retired, and walk about 10 miles a day for exercise. To stave off boredom, I take lots of plant photos for later ID. It's a great hobby. When I find something that has not been recorded in this area, I submit a specimen to our state Botanists for their review.

I have a decent plant press with plywood covers, newspaper for specimens, matted fiberboard for some give, and cardboard separators. I also have foam inserts for thicker specimens, and heavy duty, adjustable straps for pressing. As you suggested, I include the basic info (name, date, GPS location, possible plant species if known, and sample number) on the newspaper that houses the sample. I also provide an email summary with detailed measurements and observations.

I do have several keys. However, Rubus is a poorly understood genus, and herbarium specimens are often misidentified. One reason is that there might be 2 or 3 different species at the collection site, and so mixed samples occur. Another is that the genus is complex, and not heavily studied (maybe in part, because of those darned prickles).

I did talk to a couple of knowledgeable Botanists (one in Arkansas and one in Missouri), and the Rubus keys are being rewritten as we speak. They do want specimens that are properly collected, as current species lists are inaccurate. For example, Arkansas has 2 or 3 dewberry species typically reported. But using a draft of the new Missouri key, I found 5 dewberry species here in just a couple of hours.

I did get general guidelines for collecting. However, one source said it typically takes two sheets for dewberry collections, and six sheets for blackberry and raspberry collections. The second source gave the following suggestions (paraphrased), which makes me think two sheets for any species will work: In general, roots are not needed for the ID. The collector must may an observation as to whether the plants are rooting, or non-rooting at the tips. You need to make primocane and floricane collections from the same root stock. That can be a bit difficult, since some primocanes will be somewhat immature when collecting floricanes. The collection should include the mature leaves from the middle of the canes. For tip rooting species, a collection must be made from the main stem of the primocane (to show mature leaves), not the lateral branches.

So my plan as this time is to press a primocane specimen from the plant's center (mature leaves and a decent length of stem) that shows both sides of the leaves. The second sheet would show the floricane inflorescence. I think the same procedure will work for blackberries and raspberries too, but probably need to check with the folks who will receive the specimens prior to collecting samples next spring. I want to avoid 6 sheet samples, if possible, because that would limit me to just 2 or 3 specimens in the plant press at a time.

So the reason I posted initially, was to see if people here were experienced in Rubus collections. But in the end, I probably just need to go with recommendations from our Botanists.