I have been building a collection of laminated fern fronds.
I press fronds for several days or a week (between newspaper and cardboard, held by plywood and bolts)
and then take the press to the copy store and have the fronds laminated. ($2/sheet @ STAPLES.)
The result can be handled a bit roughly (passed around in class) without damage. The gross morphology is well preserved for a year and a half and counting. Fine detail may be damaged, but perhaps more complete drying would help. The color fades, slowly in the dark.
Several of the images I have posted are simply scans of those laminated sheets. (Others are scans of 35mm prints.) This summer I will try scanning unlaminated fronds, pressed and unpressed.
But I am reasonably pleased with the image quality of e.g. Polystichum braunii or Cystopteris tenuis.