Opuntia ficus-indica

I collected a specimen for the herbarium on 4 November 2018

Thanks Rosemary. How do you dry these succulents? Or do you leave that to the Herbarium?

Tha advice I was given when volunteering for AWC at Scotia was to press them, then ASAP put them in a freezer overnight to break the cel mambranes, then change the paper as often as necessary until they were nearly dry. This might be more than twice a day initially. Not a bad idea to do that even for Portulaca.

I use a technique that includes freezing - it's bit more complicated and inevitably involves getting cactus hairs in your fingers!
1. Slice open the fresh cactus "pad" longitudinally through its width so you end up with two flat halves each with the skin on one side and the cells on the other. If flowers or fruit are present also slice through them longitudinally (several times for the fruit depending on the diameter) in the same plane as the pad, but make sure that one "slice" of each flower or fruit is still attached to the pad.
2. Lay each pad-half on newspaper with the cell side upwards and pour a dense salt layer (1-2 mm think) over it (I don't pour salt on the cut flower or fruit) and leave for a couple of hours. The salt draws water out of the fresh cells. Use a paper towel or sponge to carefully mop up the water.
3. Repeat step 2 a couple more times.
4. Put each pad-half with the "free" slices of flowers & fruit between 4-5 layers of newspaper and sandwich it (pad-half + newspaper) between pieces of corrugated cardboard, tie it up so it all holds together (I use a light-weight plant press).
5. Place the bundle from step 4 in the freezer overnight.
6. Remove the bundle from the freezer and for the next couple of days carefully change the damp newspaper and damp cardboard every 3-4 hours. Together with the salt treatment, this will allow much of the moisture to be removed from the specimens.
7. Put the specimens between fresh cardboard and newspaper into a press and into a drier. Change the newspaper as needed - probably at least once a day initially. If you just bung the press in the drier and leave the specimens for a couple of weeks without checking them, you end up getting newspaper firmly stuck to the cut sides of the pads, fruit and flowers (and are likely to damage the latter two trying to get it off).
It's time consuming, but works!