22 MISC. PUBLICATION 568, U. S. DEP'T. OF AGEICULTUEE 



but the method is impractical, especially in the Tropics, because folders 

 used for collecting become wet, wrinkled, or even badly soiled. For this 

 reason, plants should be pressed in fresh folders, keeping those in the 

 collecting case for repeated field use. 



The arrangement of the specimens on the newspaper sheet for pressing 

 requires a degree of care or even imagination. One needs to keep in mind 

 the final appearance of the specimen when mounted within the frame 

 (113/2 by 163/9 inches) of the mounting sheet (see figs. 5-24). The mounted 

 plant in figure 15 shows that a free space must be available in the lower 

 right corner for attaching the permanent label. The sheet should be filled 

 as completely as possible without overcrowding. Pressing will not be 

 satisfactory if thicker stems or bulky portions occur in the center of the 

 press; therefore the lumpy parts should be arranged to he along the mar- 

 gins or in the corners if possible (see figs. 13, 14, 19). Also it is best to 

 alternate them so they will come in different places and thus keep the press 

 level. Low places can be sought out by pressing down with the hand. 

 At times, paper can be wadded around a thick fruit or stem to keep 

 the nearby leaves flattened during the drying period. Never press plants 

 with matted roots filled with gravel or soil (see p. 17). Sprays of woody 

 plants should be about 10 inches long. Small plants should be sufficient 

 in quantity to fill the sheet (fig. 12), but they should not overlap while 

 drying, because they are apt to stick together and thus be difficult to 

 separate without breakage. Broad, or long, leaves can be partly folded 

 over, or bent at an angle (figs. 6, 10, 23). 



If a plant is too long to fit on the sheet, the stem can be bent sharply 

 at some convenient place to make a V. Slender plants up to 3 feet high, 

 if not too leafy or branched, can be made to fit within the size limit by 

 bending the stem sharply to form a narrow N, or even a W-shape (see 

 figs. 7, 13, 15-17). When such plants are too leafy or branched to con- 

 form to this treatment, it is sometimes desirable to divide the plant 

 into sections, pressing the parts separately. For instance, arrange the 

 roots and basal leaves in one part, the central stem in another, and the 

 terminal flowering section in a third. In these cases, it is necessary to 

 mark the various sections by writing "Sheet 1," "Sheet 2," or "Sheet 

 3" after the collection number (figs. 5-8, 18-20, 22-24). Here again an 

 outline sketch or a photograph might be valuable to indicate the rela- 

 tionship of the various parts. 



Densely clustered twigs, leaves, and flower or fruit clusters should be 

 pruned down so that all parts can be seen clearly and so that the speci- 

 men will not be too thick (figs. 7, 8). Thick specimens are difficult to 

 dry and also to mount. Careful selection at the time of collecting should 

 yield specimens that will lie flat on the sheet, as well as display an 

 adequate quantity of flowers or fruits. Sometimes woody stems and 

 roots have to be split, pared down, or pruned to make them lie flat 

 (figs. 13, 14, 19). Enlarged knots or nodes can be pared off. So far as 

 possible, the excess parts should be pruned from the back (not the 

 front) of the specimen. 



Rigid or thorny plants can be flattened before drying by crushing 

 them between two boards. Some stiff plants, especially grasses, give 

 considerable trouble in drying because the stems will not remain in place 

 after bending. This difficulty can be overcome by inserting the bent 

 stems into slit paper rectangles (fig. 17). The rectangles can be cut in 

 various sizes from heavy paper or thin cardboard and kept on hand 

 until needed. 



