Pressing fruits (Dan Pittillo & John Nelson)
Thin fruit sections can be prepared for mounting:
1. Watermelon, most cucurbits- Select one no larger than the herbarium sheet, preferably about 9 inches across. Cut perpendicularly halfway between stem and blossom scar a quarter-inch thin section. A thin peel can be cut from the surface for flat section of exocarp. Liberally salt the section and place between two sheets of wax paper. Peel sections need only one sheet of wax paper to prevent sticking. Salt helps draw water out of the section and will help preserve it, accenting the placenta and vascular system. Hopefully a few seeds, young or old, will be exposed upon drying. The section can then be glued to the herbarium sheet after thorough drying.
2. Other juicy fruits such ad Citrus, Poncirus, Maclura, et al. may use this same technique. Fruits such as large grapefruit will require sawtooth blade bread knife to make good sections. Large, prickly or bumpy exocarp fruits may require a bit of testing. Gloves will help with prickles (such as cactus!) or digestive juices (such as Maclura). Best thing, of course, is to pickle fleshy fruits, as long as you have the space for them in jars, but there are the OSHA regulations about storing stuff.
3. Nuts- something like a hickory nut can be thin sectioned with a hack saw. A vice or miter holder (miter helps hold nut by hand and less binding than vice) makes the process easier; it can hold the fruit while it is being sectioned. Parallel cuts about 1/8 inch apart can be made through the desired section direction (either longitudinal or cross). The first cut can be partial, leaving part of the fruit to support the nut in the vice while the second cut is being made. Finally finish one cut, take from vice and free-hand finish the other cut. After drying, the section can be glued to the herbarium sheet or placed in an envelope. Re-closable plastic bags can be used for sections and stapled to the margin of the herbarium sheet.
Whole fruits can be mounted
1. Berries such as juicy blackberry, raspberry, strawberry- ripe fruits spread when pressed but will retain seeds and juice color for a while. Near mature fruits will work better and bulky strawberries may be sectioned and pressed similar to number 2 above.
2. Hexastylis fruits- Tom Wieboldt described a good technique in Chinquapin (2006, vol. 14.3) for preserving shape of fruit. Longitudinally cut in half, ink surfaces of outer calyx and pistil, and print on cotton paper. The halved sections may be press-dried and included with the mounting.
3. Asclepias follicles: green ones can be sliced longitudinally and then pressed. It's sort of a pain having the seeds start flying everywhere if you are doing a ripe, dehiscing one, but the thing can be secured with a rubber band, pressed, and mounted whole.
Other fleshy plants
1. Bulbs, corms, rhizomes- can be sliced longitudinally before pressing still attached to the stem. Slice through middle and press one side up and other down in pressing. Salt can help with wax paper to dry better.
2. Fleshy stems such as Arisaema, Trillium & other lilies- stripping surface helps in drying but save stripped section with specimen.
3. After initial pressing, remaining succulent parts may be crushed to complete process. This can be as simple as crushing under foot or using a heavy weight to pound gently.
1. Typha is a real problem during drying and fluffing out. The spike can be slipped inside some sort of skinny bag, or a piece of waxed paper carefully glued around/over it on the sheet.
2. Tree ferns and huge plants- usually must be sampled for features. A frond section with sori (or vegetative only) may be selected to fit the herbarium sheet. If possible, maybe thick stems may be pealed or cross-sectioned for surface and anatomical features.