What are the procedures and key points of collecting and making plant specimens?

The most common plant specimen is wax leaf specimen.

Wax leaf specimens, also known as pressed specimens, are usually made by pressing fresh plant materials with absorbent paper and binding them on white hard paper (this paper is called surface paper).

Wax leaf specimens are of great significance to plant classification, which enables botanists to check and collect them all year round.

Specimens from different regions. Some large herbarium often collect more than one million wax leaf specimens, which botanists use for description and identification. /kloc-The rapid development of plant classification in the second half of the 6th century was largely driven by the new technology of wax leaf specimens.

The significance of wax leaf specimens is not limited to the study of plant taxonomy. In the eyes of ordinary people, the collection and production of wax leaf specimens are more due to a feeling of nature and life, a tradition and a complex of natural history. Of course, the aesthetic feeling brought by the wax leaf specimen itself is also an important aspect.

The production of common plant specimens generally pays little attention to aesthetics and color preservation. However, if it is a plant specimen for a popular science exhibition or for decoration, more attention will be paid to whether the specimen is flat, beautiful and how to preserve its color.

Manufacturing sequence

Repair and maintenance

Select the plant with the most complete organ from several identical plants as the specimen. Remove the residual leaves first, and properly remove some too dense branches and too many flowers, leaves and fruits. If 10 large flowers gather together, it is generally appropriate to leave only 4~5 flowers, but a small piece of flowers, fruits and leaves should be left to show the original ecological situation. To make a solid object into a plane, you need to cut off 1/2 or 2/3 to avoid accumulation. Before absorbing paper, it must be reshaped, that is, the branches, leaves, fruits and flowers of the specimen should be laid flat to avoid overlapping. Try to keep the specimen in a natural state and look beautiful. Some berries, tubers and tubers that are inconvenient to press should be preserved by soaking.

restrain

Spread some absorbent paper on the specimen rack and put the folded absorbent paper together with the plant specimen. Before pressing, open the folded absorbent paper, check and correct the position of flowers and leaves, and turn over a few leaves and flowers for comprehensive observation. After straightening, fold the absorbent paper in half, put several layers of absorbent paper on it, and you can put another one. Add this layer by layer and put it together. Finally, tie the specimen tightly with thick rope, press it on a big stone weighing dozens of kilograms and put it in a ventilated place. Change the paper to dry the next day, and the specimens must be carefully treated and classified. On the first day of repression, every other day

Dry paper can be changed once every five hours, twice a day the next day and once every 24 hours after two days. Generally, plant specimens take 3 to 7 days. On the third day, after changing the paper, the pressure can also be increased (the splint of 250~300 specimens can apply a pressure of 125~ 150 kg). Under direct sunlight, water can evaporate quickly, which can prevent excessive discoloration or mildew. In rainy areas, dry the paper twice a day and bake it with low fire, and it can be dried in about 3~4 days.

How dry is the specimen? You can pick up the specimen by hand. There are no dry specimens, and some parts are soft and easy to bend. Specimens that are too dry are fragile and difficult to break. Moderately dry samples are elastic.

In the process of pressing, the fallen flowers, fruits and leaves should be packed in paper bags, and the number of the specimen should be marked so as to be attached to the paper.

label

Put the dried specimen on the desk paper, set the position and fix it. Attention should be paid to the scientificity and artistry of the specimen when fixing. Fixation can be done by sticking a strong thin paper strip or glass paper strip on the branches, then sticking both ends of the paper strip on the dining table paper, or cutting a small opening at the fixing place with a knife and sticking one end of the paper strip through the small opening on the back of the dining table paper. You can also nail the specimen to the surface paper with white cotton thread. Small plant specimens or specimens with soft branches can be coated with glue on the back of the specimens and pasted directly on the surface paper.

After loading the table paper, put a label under the table paper. Finally, paste the specimen lining paper with the same size as the desktop paper on the upper edge of the desktop paper to protect the specimen.

protect

Wax leaf specimens should be classified and placed in specimen cabinets or specimen boxes, and mothballs should be placed between specimens to prevent moths. In spring and rainy season, the specimen should be placed in a ventilated and dry place to prevent the specimen from becoming moldy. If there is a specimen room, it is best to close the doors and windows in early spring and steam the formalin solution on an alcohol lamp for 3 days to prevent insect decay.

Impregnated sample

concept

For teaching, scientific research, exhibition and other purposes, it is often necessary to preserve the whole plant or part of the plant for a long time, and to achieve this goal, it is necessary to soak the plant specimen in a certain drug solution. A specimen made by soaking in a drug solution is called an immersion specimen.

manufacturing method

Formalin impregnation method

The specific method is as follows: the commercially available formalin and clear water are mixed into a 5% or 10% solution and placed in a specimen bottle (specimen cylinder). Then clean the collected plant specimens and put them in a specimen bottle (specimen tube) and soak them in the liquid medicine (if the specimen contains more air and cannot sink in the solution, you can press the plant specimens into the soaking liquid medicine with heavy objects such as glass slides or other porcelain). Finally, cover the bottle cap, seal it, and put a label on the outside of the specimen bottle, indicating the name, characteristics and impregnation date of the plant specimen. In this way, an impregnated specimen is made. The prepared plant specimens should be kept in a cool place without strong light.

Advantages: this method is simple and economical, but it can't keep the original color of the specimen, which often reduces the use effect of the specimen.

Primary color preservation method

There are many formulas of color protection solution, but so far, the selected formula of color protection solution only has a good color protection effect on green, and the color protection effect on other colors is unstable. This paper introduces the formulas of several color-preserving solutions and the methods of making plant specimens preserved in primary colors for readers' reference.

(1) green preservation method

Plants are green because there is chlorophyll (in chloroplasts) in plant cells. Chlorophyll is a complex organic compound (its molecule is a complex structure centered on magnesium ion), and magnesium ion in the molecule is easily decomposed by alcohol and formalin, which destroys its molecular structure. Replacing magnesium ion in chlorophyll with copper ion can form a new "chlorophyll molecule" centered on copper ion, which can be stably preserved in alcohol, formalin and other preservation solutions, so that green can be preserved for a long time.

① glacial acetic acid-copper acetate mixed stationary liquid (rapid green preservation method)

Preparation of mother liquor

Slowly add the copper acetate (or copper sulfate) crystal into 50% glacial acetic acid aqueous solution (which can be heated slightly) until it no longer dissolves, and obtain the mother liquor (saturated glacial acetic acid-copper acetate solution) for later use.

Treatment process

In the process of plant specimen treatment, firstly, pour 1 part of mother liquor into a beaker, then add 3-4 parts of water to dilute the mother liquor in the beaker, and then when the solution in the beaker is heated to boiling, put the plant specimen to be treated into the beaker to continue heating. Soon, the green part of the plant specimen gradually turns brown (this is because acetic acid reacts with chlorophyll to form plant melanin). Before long, the plant specimens turn green again (this is because the plant melanin reacts with copper acetate to form a new "chlorophyll" molecule centered on "copper"). At this time, the plant specimens can be taken out, washed with clear water, and then stored in 5%~ 10% formalin solution for a long time.

If you want to make wax leaf specimens, you can use absorbent paper to absorb water, press it dry, and then make them into specimens according to the procedure of making wax leaf specimens.

② Copper sulfate-sulfurous acid mixed stationary solution

Put the light green plant specimen in the mixed fixed solution of 2.5% copper sulfate and 1% sulfurous acid for 7-8 days. When the green color of the plant specimen is slightly darker than the original color, take the plant specimen out of the fixed solution, rinse it with clear water and store it in 1% sulfurous acid solution.

③ Copper sulfate fixed solution

Plant specimens were fixed in 10%~ 15% copper sulfate aqueous solution for 10~ 15 days. When the plant specimen turns dark green, take it out of the stationary solution, wash the copper sulfate on the plant specimen with clear water, and then save the plant specimen with 1% sulfurous acid solution.

(2) Red preservation method

① Formalin-boric acid mixed stationary solution

Put the red plant specimen (such as peach) into the mixed fixed solution of 1% formalin and 0.08% boric acid and fix it for 1~3 days. When the plant specimen changes from red to brown, take it out and clean it, and store it in the mixed storage solution of 1%~2% sulfurous acid and 0.2% boric acid. If the plant specimen is green (such as peach), a small amount of copper sulfate can be added to the preservation solution. When the color of the green part of the specimen deepens, take out the specimen, clean it, and store it in the mixed storage solution of 1%~2% sulfurous acid and 0.2% boric acid.

② Copper sulfate fixed solution

Plant specimens with green in red, such as red pepper and watermelon with green calyx and branches and leaves (the red placenta of pulp should be cut and fixed); Red-green plant specimens, such as sugarcane, can be fixed with 5% copper sulfate solution 10~ 15 days. When the plant specimen changes from red to brown, take it out and wash it, and then store it with 1%~2% sulfurous acid.

(3) Yellow preservation method

(1) copper sulfate fixed solution

Yellow-green or yellow plant specimens, such as pumpkin, potato, melon, pear, etc. , fixed with 1%~5% copper sulfate for 1~5 days, taken out and washed, and then stored with 2% sulfurous acid, 1%~2% alcohol and a small amount of glycerol.

② Sulfuric acid-formalin mixed stationary solution

Plant specimens such as pear, potato and arrowhead can be directly fixed with mixed solution of 2% sulfurous acid and 0. 1% formalin. When the liquid medicine is turbid, it needs to be replaced with a new liquid medicine in time.

(4) purple preservation method

① sodium chloride-formalin mixed stationary solution

Plant specimens (such as purple grapes) are fixed with a mixed solution of 3% salt (sodium chloride) and 2%~3% formalin for 2~3 months, taken out and cleaned, and then stored with 1%~2% formalin solution.

② Hertzian solution

200 grams of zinc chloride was dissolved in 4000 ml of distilled water, showing milky white. Filter while it is hot (it is not easy to filter, you can use an air extractor). Add 100 ml formalin and 100 ml glycerol to the filtrate, that is, He Cheng filtrate. After the solution is cooled, put the prepared plant specimen in a specimen bottle and seal it, which can be preserved for several years.

(5) pink preservation method

Flowers such as peach blossom, rose and begonia are soaked in 0.2%~0.3% sulfurous acid solution for about 5~ 10 hour. After the pink is bleached by sulfurous acid, a small amount of formalin is added in time, and it returns to pink after 1~2 hours. When the pink color changes to purple after 10~20 hours, the plant specimen immediately turns to 0.

(6) White preservation method

① sulfuric acid fixed solution

Bleaching with 3%~5% sulfurous acid for 7~ 10 days, taking out and cleaning, and storing with 1% sulfurous acid.

② Copper sulfate-sulfurous acid mixed stationary solution

Plant specimens with green stems and leaves, such as white radish and Zizania latifolia, are fixed with 5% copper sulfate for green 1~3 days (Zizania latifolia should be fixed for 3~ 10 days), then the specimens are taken out, washed and stored in 1% sulfurous acid; If the color is not white, it can be bleached with 1%~2% sulfurous acid or hydrochloric acid, and then stored with 1% sulfurous acid.

Advantages: the color of the original plant can be preserved.