Procedures for making preserved leaf specimens

Pressing the specimen is to spread the specimen on several layers of absorbent paper one by one, and then press it up and down with the specimen clamp to make it dry and flatten as soon as possible. The pressing method is to first put several layers of absorbent paper on one splint of the specimen rack, then put the specimen, then put several layers of paper on the specimen, so that the specimen and absorbent paper are separated from each other and stacked layer by layer, and finally press the other splint of the specimen and tie it tightly with a rope. The stacking height should be tied firmly without dumping, which is generally about 1 ft. Generally, there are 3 to 5 sheets of paper in each layer. Thick and juicy specimens have more paper sandwiched up and down. Light and soft flowers and fruits can be wrapped in soft paper before being sandwiched to avoid damage. The first pressed specimen should be tied as tightly as possible, so that the specimen can be flattened, closely contacted with absorbent paper and dried more easily. After 3 ~ 4 days, the specimen began to dry and gradually became brittle. At this time, it should not be tied too tightly to avoid damaging the specimen.

Pay attention to the following conditions when pressing: 1. Try to make branches, leaves, flowers and fruits flat, and make the back of some leaves face up, so as to observe the characteristics of the back of leaves. It is best to display the shapes of flower stalks, calyx, petals and other parts by lateral pressure of some flower specimens; It is also necessary to dissect several flowers and press the stamens, pistils, flower discs, placentas and other parts so as to dry them with absorbent paper, which is more convenient for observing the characteristics of plants and identifying them. 2, succulent roots, tubers, bulbs and other specimens, not easy to dry, you must first scald the cells with boiling water, then cut them vertically and horizontally, drip dry water and then press. This can not only dry the specimen quickly, but also observe the internal structure. Cactus and large fruits, such as grapefruit, bergamot, citron, etc. , can be cut longitudinally to remove the internal fleshy tissue and then pressed, or cut part of the longitudinal section and transverse section as a representative to press. 3. Plants such as Cuscuta chinensis, Taxilli, Ginger, Taro, Orchid, Pine, Cunninghamia lanceolata, Cypress, etc. are often pressed for 1 ~ 2 months, but the cells are still not dead, causing the leaves and flowers to fall off. These specimens need to be scalded in boiling water for a while, and then pressed after killing cells. Some specimens are easily broken, such as the petals of kapok, which are left for half a day after collection, or steamed for a period of time to soften the tissue and then pressed, and the effect is good. 4, specimen placement should pay attention to the wrong end, in order to maintain the balance of the whole stack of specimens, uniform stress, not dumping. Some specimens have thick flowers and fruits, which often make the paper swell and the leaves wrinkle under pressure. In this case, several pieces of paper can be folded into paper mats and placed around the protrusions, or most of the paper can be cut and dried separately, but pay attention to hanging the same collection label. If the specimen is long, it can be folded into a "V" shape or a "K" N "shape. 5. Whether the paper is changed in time is a key step related to the specimen quality.

The water content of the initial pressure specimen is high, and it is generally changed 2-3 times a day, once a day after the third day and once a few days later until it is dry. In rainy weather, specimens are prone to mildew, so it is more important to change paper. Pay attention to plastic surgery several times before, and spread out the wrinkled leaves and flowers to show the main features. The replaced wet paper should be dried or dried in time. It is best to use dry hot paper instead. Be careful when changing paper. First, remove the wet paper from the specimen and replace it with some dry paper. Then, press one hand on the dry paper above the specimen, and press the wet paper below the specimen with the other hand, and turn it quickly so that the dry paper faces down and the wet paper faces up. Then, remove the wet paper and replace it with dry paper, which can reduce the movement of the specimen and avoid damage.

The drying speed of plant specimens with different textures is different. Some specimens, such as plantain, nightshade, morning glory, dandelion, etc. It will be dry in 2 ~ 3 days, and some will take half a month or a month. Therefore, when changing paper, you should take out the dried specimens at any time to reduce the workload.

Flowers, fruits and seeds of some plants often fall off under pressure. When changing paper, you must pick it up one by one, put it in a small paper bag, write down the collection number and clip it together. In order to make the specimen dry quickly and keep its original color, it can be ironed and dried, or it can be dried in a constant temperature drying box at 45 ~ 60℃ with a wire clamp or accelerated by infrared radiation. In addition, the use of silica gel as desiccant can make plant specimens dry quickly with good results. Binding is to fix the specimen on a piece of white surface paper, also called surface paper. On the one hand, the purpose of binding is to preserve specimens for a long time without being destroyed, on the other hand, it is also to facilitate observation and research.

Table paper requires hard texture, and it is best to use white paper or forest paper. When in use, it is cut to a certain size as required. Specimen binding is usually divided into three steps, namely disinfection, binding and recording.

Disinfection: after the specimen is dried, there are often pests or eggs, which must be disinfected with chemical agents to kill the eggs and spores of zero bacteria to avoid moth-eaten. The commonly used disinfectant is 1% mercuric chloride alcohol solution. It can also be fumigated and disinfected with sulfur dioxide or other agents. These are highly toxic drugs, so you should pay attention to safety when disinfecting. Ultraviolet disinfection is safer and more effective.

Binding: To bind the specimen, first choose a suitable position on the surface paper. Generally, it is straight or slightly inclined, and the upper left corner of the paper has a lower right corner for posting collection records and labels. Pay attention to the beautiful shape when placing, and reflect the true shape of plants as much as possible. After the position of the specimen on the surface paper is determined, the leaves, flowers and branches that are too dense should be trimmed properly and then bound. Specimens are usually bound by indirect pasting. The specific method is: select several fixed points on the front of the dining table paper, use a flat awl to make several pairs of longitudinal seams close to the branches, petioles, inflorescences and midrib of leaves, insert both ends of the paper into the seams and put them on the back of the dining table paper. After tightening the paper, stick them firmly on the back of the desk paper with peach gum, and then fix the anatomical specimens such as flowers, fruits, bark and other accessories on the desk paper. Flowers and fruits that fall off easily should be packed in paper bags and pasted on the table paper. So the paper bag should be stuck firmly, don't lose flowers and fruits, and it should be easy to take out. Large paper strips such as roots and fruits are not easy to fix, so white sewing thread can be used instead, and thin specimens can be directly attached to surface paper with peach gum. If there is no peach gum, you can also use ordinary office gum or paste with preservatives instead. Tiny plants, such as moss, lichen, spirogyra, auricularia, etc. It is not easy to bind with the above method, and the specimen can be covered with transparent cellophane, and the periphery of cellophane is stuck on the surface paper. Only one plant specimen can be placed on each table paper. Compare specimens. According to the need, put the same specimen on a table paper.

Labeling: after the specimen is bound, label it in the lower right corner, and the label items are drawn up as required. Generally, there are categories, names, collection locations, dates, collectors, etc. The explanation should be concise. The category is to write the name of the specimen, such as leaf order specimen, inflorescence specimen or phylogenetic specimen. Name refers to the name of the plant. If it is a leaf order specimen, there may be several different plant names on the table paper. Specimens used for plant taxonomy are usually marked with collection records in the upper left corner and name labels in the lower right corner. The naming label shall indicate the preservation number, family, Latin scientific name, appraiser and identification date. Just stick the four corners or the upper and lower sides firmly when labeling, and you can remove them and replace them if necessary. The prepared wax leaf specimens must be properly preserved, otherwise they will be easily eaten by insects or moldy, causing losses. Wax leaf specimens should be stored in the specimen cabinet. The specimen cabinet should be structurally sealed and moisture-proof, and its size and style can be determined according to needs and specific conditions. Generally divided into two layers, easy to move. Each floor is 100 cm high, 70 cm wide and 45 cm deep. There are doors facing each other in front of the cabinet, and the middle is divided into two sides with wooden boards, and each side is divided into five compartments with movable boards. Samples are sorted and placed on the plate. If there is no specimen cabinet, a sealed wooden box can be used instead. The specimen cabinet must be placed in a ventilated and dry room.

Two things must be done before the specimen enters the cabinet: registration and numbering. Each specimen should be classified as required and registered in the register. The main purpose of registration and numbering is to record how many specimens are kept at any time and which specimens can be taken at any time, thus making the specimens more organized and easy to use.

Before disinfection and preservation of specimen cabinets and specimen rooms, they should be cleaned, dried and disinfected with pesticides in advance, and generally sprayed or smoked with trichlorfon or formalin. Then put the specimens in the cabinet for preservation according to the registration and classification order. After the specimen is put into the cabinet, it must also be checked regularly for mildew, insect pests, damage, etc. If found, it should be handled in time. Dry the specimens thoroughly before entering the cabinet, and put mothballs and desiccant in the cabinet. If the specimen is moldy, you can gently sweep off the mycelium with a brush, and then touch some carbolic acid or formalin on the specimen, or you can dry it with an infrared lamp and disinfect it with an ultraviolet lamp. Be sure to close the cupboard door when sampling. After joining the cabinet, against the tide will sometimes be in rainy season, and special attention should be paid to the south.

In addition, when taking and placing specimens, some parts of the specimens will fall off and be broken due to mutual friction between the specimens. This needs to be handled carefully. When you need to take samples from a pile of specimens, you must take them out of the whole pile and put them on the table to read one by one. Do not force them. In order to reduce the wear between specimens, the specimens can be clamped or classified one by one with kraft paper or hard paper.