K. Maden / Our Nature (2004) 2:53-57 Plant Collection and Herbarium Techniques K. Maden Tribhuvan University Department of Botany Post Graduate Campus, Biratnagar, Nepal E-mail: [email protected] The collection of plants began in the 16 th clipper, heater. century. Later, J.P.Tourefort (ca 1700, France) v) firstaidbox, topographicmaps, computer, used the term herbarium for plants (Bridson binocular and Forman 1999). Plant collections are essentials for taxonomic researches because Collection procedure they serve as voucher specimens. They also Twig with good flowers need to be help to identify the family, genus and species. collected for the specimen. The portion of the So a herbarium is basically a storehouse of specimen should have to contain clear botanical specimens, which are arranged in the phyllotaxy and the branching system. For small sequence of an accepted classification system, herb, collection of more specimens as could and available for reference or other scientific fix on the herbarium sheet (up to six) is study. desirable. In general, secateurs are used to Once mounted and deposited in the cut the twigs, while for a bit height or down, herbarium, the collections are referred to as pruner is used, and for spiny specimens, such herbarium specimens. Such herbarium as Berberis mucrifolia, leather glove is specimens can be stored for many years and required. For ferns and herbs, digger is applied as such, they serve as: (i) historical collection, to take out underground portion. Some plants (ii) reference collection for checking the stem lies horizontally under the ground; for identity of newly collected plants, (iii) as an example, some Salix and Myricaria species. aid in teaching, and as a source of research In such cases, the underground portion should material. Taxonomic research, therefore, relies be cleaned from the soil particles, etc. If it is upon a collection of preserved plants built up stem, then, specimens have be contained over a long period of time- the herbarium. branching manner. Materials required for plant collection. Aquatic plants are filmy or somewhat i) plant cutter (secateur), pruner, digger, knife, filamentous and are difficult to be arranged leather gloves. on the sheet. A sheet of mounting paper is ii) field note book, pencil, permanent ink pens, placed under a floating or submerged minute magnifying glass, digital camera, flora book plants, and then slowly raising the paper until (colorful), forceps. the specimen is lying on the paper and out of iii) flimsies or newspaper, blotters, corrugated the water. Then paper is lifted making a slope plates, herbarium pressure, straps, tissue carefully, so that it facilitates water runoff. paper, plastic (poly) bags, herbarium bags. These plants need to be shaken well before iv) drying table, mountain survival blanket, putting in flimsies. Some plants can be put in 53 K. Maden / Our Nature (2004) 2:53-57 plastic bags. The plants that easily damage or be taken even if the flower is too small. The can be lost among larger plants from the same range, latitude and longitude as well ecology collection site can be placed in small bags of plant need to be noted down by GPS (Global within the larger bag. Diseased plants, Positioning System) and eyesight vision. depauperate specimens, infected twigs, etc. Likewise specimen’s microhabitat; means should be avoided. associated species should be mentioned, at At the time of collection, it is usually not least five species. Finally the distribution status possible to identify many specimens in the field. of plant also needs to be mentioned, either the Therefore, botanists identify the specimens that collected species is rare, frequent, common, have been pressed and dried. The specimens locally common or occasional. Duplicate are grouped into bundles according to location. specimens of one species that are collected The confirmed specimens should contain their on the same date and same locality should be botanical name, including author. The collection given the same collection number. number can be used as a specimen tag. These number usually begin with 1, 2, 3, etc., and Pressing continue indefinitely. Plant collectors When time and carrying facilities permit, sometimes use a modified system, beginning the most usual method is to press each each new year (2004 -1, 2004 -2, 2005-1, 2005- specimen as it is collected. Another method is 2, 20040512-1, 20040512-2, etc.). Instead of to accumulate the specimens in vasculum (also tags, collection number also can be written in black colored plastic bags can be used for short flimsies by marker. duration, especially in high altitude) and pressed later. Specimens should be of good quality with Field Note good field note. Collection numbers have also After specimen collection, a field record is to be written in the flimsies (newspaper or noted in small pocket sized notebook. Date of blank newspaper). The specimens are kept collection, location (name of place or distance gently within newspaper. Parts of flower are from definite point)), collection number, if much carefully spread without overlapping in possible, name of the specimen, and original shape. If the specimens are long, then description of the floral parts that may change it needs to be folded in V and N or Z shape. after drying are noted down. The good quality Unnecessary overlapping leaves and other specimens also become worst if it does not parts must be avoided. Large leaf, if palmately have good field record. Topographic map is compound, split in half lengthwise and one half essential for the location. It needs to examine is discarded. If pinnately compound, a branch the floral parts carefully, if small by using is only kept. A few leaves may be turned over magnifying lens. The characters should tally to show lower and upper view. If there is bulgy with the literature and pictures of the books. rhizome, needs to cut or dissect longitudinally From various angles, the flower photos require by knife, so that moisture evaporates through to be taken. there. If the specimen is gymnosperms, like Dorsal and ventral leaf view photos are also Abies spectabilis (leaves fall before dry), the essential for the further identification specimens needs to deep in the glycerin before confirmation. Digital camera should have at pressing. Flowers with gamopetalous corollas least 5-mega pixels so that close up image can should have to be pressed a few flowers 54 K. Maden / Our Nature (2004) 2:53-57 separately and some of these split open and accomplished without heat, and those with the spread. If flower is large, cotton padding is aid of artificial heat. Drying with the aid of often helpful to dry quickly. artificial heat is the prevalent method. It is The specimens thus kept inside flimsies, are accomplished by means of heated dry air covered by on either side by blotters and then passing up and through the canal of the it is put herbarium pressure. After press is filled corrugate. Corrugates, often referred to as or all the specimens pressed, the plant press is ventilators, are used in presses when plants closed and pressure applied by means of are dried by means of artificial heat (Lawrence tightening the straps. Hard and dried fruits and 1951). It is as sheet of pasteboard or thin cones- need not preserve and press, but have aluminum metal, with fluted ducts. It provides to keep in special boxes. The final appearance air passages through the press for movement of the specimen depends on how it is pressed of dry heated air. and dried (Jones and Luchsinger 1986). The dryer with the herbarium pressure is covered by mountain survival blanket. It is heat Re-pressing resistant blanket that is attached to stand with The specimens are repressed in the evening clips. At the base (single) for coming and at in the camp. The blotters are changed, if they the tip, for out going air, series ventilations need are moistened. But flimsies need not change. to keep. The best heat source is heater. Stove The specimens are kept with the new blotters. can be used as an alternative source. The usual After blotter, for ventilation and equal heat time period for drying specimens is 12 hours. diffusion, aluminum plates (corrugates 12 X But it depends upon the material; and also dryer set, humidity, the type of heat source, climate, 18 in.) are placed. The process is repeated and temperature affect the drying period. Too for each specimen. Thus racked specimens high a temperature for too long a time period are designated as corrugated-blotter-flimsies will cause a specimen to become brittle and with specimen-blotter-corrugated. Then it is discolored. Too short a drying period or too tied up inside the herbarium pressure or plant low a temperature will keep the specimens, pressure by two straps or belts around the moist to touch, and possibly cause mildew. outside. It is usually constructed of a sturdy Specimens will need to be checked regularly metal, plywood, or wooden grid frame 30 x 46 until dry. A specimen is not dry if it is still limp cm or 12 X 18 in. (Woodland 1997). The when picked up and cool and moist to the touch. herbarium pressure equipment can be The pressures become loose when the plants inexpensively made from wood scraps, old are dry. cardboard boxes, old newspaper, and small The most common method of drying is without applying heat. Plants are placed in rope.The final data is recorded in the computer pressing papers between the blotters of the using Microsoft Excel program, before plant press. No corrugates are used. The press specimens repressed for drying in the field. is locked up for about 24 hours, this is known Thus prepared database is helpful in future as the sweating period.