Teacher's Plant Collection Guide
This guide serves as a basis for a majority of the other experiments on the DDL site. Though not necessary, it should be read before any of the exercises on the Lesson Grid are attempted.
Ethics of Plant Collection
As a teacher conducting natural history activities with children, you have great power to influence their attitudes about natural resources and the environments in which they are found. As much as possible, model responsible stewardship. There may be times when you want to collect samples of plants for a life science unit. You may find yourself hesitating because you don't want to alter or disturb the particular habitat in which you find them. You always have to weigh the educational value of the collection against the impact of removing parts of the plant. Here are some guidelines that will help you collect plants in a responsible manner with the least amount of impact.
Make sure there are enough of the desired plant in an area. If you only see two, the plant should be left alone. On the other hand, just over the rise there may be a whole field of the plant.
Double check to make sure the plant is not protected or endangered. Your local office of the US Fish and Wildlife Service can help you.
Only take enough of the plant to serve the needs of your lesson. Never pick more than a third of a plant. If it is a solitary bush or tree, remove just a few twigs and leaves from the outer edge.
If you do need roots for study, try using noxious weeds since they are usually destroyed anyway.
Wildflowers have a slower reproduction rate and grow much more slowly than other types of plants. Collecting or disturbing could affect their survival. Use your best judgement if it is absolutely necessary to do the collection. Make sure there are plenty of the species you need and only take the plant parts of a few. If they are in their seeding mode, collect the seeds from only a couple of plants and leave the rest.
Never collect plants in a national or state forest or park or other protected area. The plants in these areas are protected for a good reason biological diversity rules!
Safety in the Field
- Survey the collecting site for potential hazards before taking your class out.
- Define boundaries of the study site. Make sure students know these boundaries. Consider using brightly colored engineer's tape to mark boundaries.
- Check for the presence of large amounts of bees or wasps around the plants you want to collect. Warn the children ahead of time to be very careful about grabbing or disturbing these insects.
- Warn students never to eat any plant or plant part.
- Check for allergies with your students and on their school medical cards. Check with your school nurse on how to deal with various allergic reactions. (Some of your students may simply need to wear protective masks.)
- Always have a back pack with a first aid kit and preferably a communication device walkie-talkie or cell phone with you in the field. Always have it packed and ready to go.
All scientists keep careful records of field experiences. Amateur scientists collect just as valuable data as professional scientists. So, it is very important to keep careful records when collecting plants. Data should contain date, weather conditions, specific locality where collected, collector's name, identification source (book, person), plant common name and scientific name genus and species.
The students should also sketch the plants as they exist in the wild. In addition, notes should contain any other observations made about the habitat in which the plant was found or of the plant itself (i.e. what was feeding on it, other plants surrounding it, plant description, and if collected specimen doesn't adequately reflect plant in wild, things such as height, diameter of stem, diameter of flower and unusual features of the plant, etc).
Methods of Preserving Plants
To get successful results from pressing, it is important to pick and then store the plants properly while you are still in the field. Keep them as uncrushed and moist as possible. It is a good idea to bring an upright container (vase-like) with water to put the plants in.
When you return to your workspace, wash off plants, if necessary. However, make sure the main parts (i.e. flowers and leaves) ARE COMPLETELY DRY BEFORE PRESSING; if not, they will mold.
The basic principle is to sandwich the plants between absorbent sheets of paper, apply sufficient pressure and allow ventilation to dry them.
You do not need a professional plant press. Books or bricks will do. Newspaper, manila paper or blotting paper are good absorbent papers. The size of the paper is dependent on the size of the plants you want to press. You can certainly put more than one plant on the paper. Just make sure they do not overlap (they tend to stick to each other in the drying process).
How to press plants:
- Make sure the plant is clean and dry.
- Arrange the specimen on two layered sheets of absorbent paper. Make sure all plant parts are spread out to show them off. Make sure your plant pressing area is on a flat, dry, hard surface in a warm, dry room.
- Put two or three sheets of paper on the plant(s). Add more plants to top sheet, layer three more sheets on top and so on up to ten layers (otherwise it becomes too unwieldy).
- On the top three layers of paper, add books or bricks to cover paper. Make sure there is sufficient weight to exert enough pressure on plants. Pile should yield to weight.
- Change sheets every two or three days. It will take the plants two to four weeks to dry completely.
- They will be very brittle so handle with care.
Three-dimensional plant drying
To preserve plants in three-dimensional condition (wonderfully life-like) you can use dehydrating agents. Plants prepared by this method are simply buried in the agent (s) and left until dry. They often retain both natural color and shape (some plants better than others). Be sure when collected, they are at their peak. Keep them fresh in water until you are ready to dry them.
The combination of Borax and play sand works very well and is easily obtainable. Make sure the ingredients are clean and dry.
- To use, mix one-part borax to two parts play sand. Boxes of borax are available in the laundry materials department of a grocery store.
- Play sand is VERY fine and is obtainable from lumberyards in (usually) 50 lb. sacks.
- For classroom drying of many plants, you can use a large Rubber Maid-like container to mix these agents and to dry plants in. Be sure not to crowd plants; they should not be touching. (You may need TWO large containers.)
- This mixture can be used over and over as long as it is clean.
How to dry plants
- Have two large Rubber Maid-like containers
- Mix agents in one.
- Divide mixture. Place one-half in one of the containers.
- In the remaining container, level out the other half of mixture. Place dry clean plants upside down and upright on top of mixture. Spread out parts. (This may take two pairs of hands!) Some plants may be so large that you need to lay them down in mixture. In this case, place them near top of mixture, spreading out parts, and cover with mixture. The idea is to have them completely covered without having so much weight on them.
- Pour remaining mixture from other container gently around positioned plants until main parts are completely covered. Usually, just the stem is sticking up above mixture. All leaves and flowers should be covered.
- Leave one plant in the corner for your "Checking plant". This is the one you can pull up and rebury to see if plants are ready. Be sure it can be "sacrificed." It may be damaged in the process. Plants are ready when they are completely dry to the touch and brittle.
- Label the containers with the names of the plants, date of burying and who plants belong to.
- Keep container in warm dry place for about 1 to 2 weeks.
- If you live in a moist area, you may consider covering container.
- At end of drying time, GENTLY pour off drying agent to expose most of plant. If plants are still flexible, THEY ARE NOT READY. Rebury them.
- Carefully take out plants one by one, tap them gently to remove excess drying agent. You can also brush them with a SOFT paintbrush that is slightly dampened.
- Plants will be very brittle so handle with care. Some times you can restore the velvety texture to plants by brushing petals and leaves VERY lightly with vegetable oil and a SOFT brush.
Making a classroom herbarium
Herbariums are ways to display the plants that you have collected.
This type of herbarium lends itself to displaying pressed plants, and can be added to as more plants are studied and collected.
- Thick Three Ring Binder
- Clear plastic three ringed protector sheets (preferably that open on one side)
- Construction paper or poster board cut to size so it fits in to cover sheets
- With light dabs of Elmer's-type glue or rubber cement place plant on construction paper or poster board. Leave room for a student-made label and sketch. This label can include the information from their data collection sheets.
- They can also type and/or print out the names of the plants, both common and scientific for pasting at the top of the page.
- If you have line drawings from a plant identification book, you can copy drawing and also include that on page. If not, the students can include their sketch or a copy of their sketch. They could use the scanner for this.
- You can do the same on the other side of the construction paper or light poster board.
- Students may come up with other additions to their pages. However, you don't want to take away from the plant with too busy a page.
Canning Jar Herbarium
This type of herbarium lends itself to displaying three-dimensional preserved plants.
- Quart canning jars - wide or regular mouthed. Jars should be of the variety that have a minimum amount of design on them. The clearer the better.
- Simply insert the plant into the jar, main part toward the bottom of jar.
- Screw lid on.
- For display, place jar lid down.
- You can decorate display table with samples of plants (not in jars) in attractive arrangements, pretty colored cloths, products made from plants i.e. teas, dyes, foods etc. Be sure to save boxes the jars were in. You can store your herbarium in boxes when not in use.
The plant label can be of several varieties. You can paste a label on bottom of jar (which is the top when displaying) or cut a narrow strip for a label that goes inside jar just before you screw lid on, or create a small free standing card-type label placed in front of jar.
Encourage students to be creative with labels and display table.
Students can divide the preserved plants according to a category ( e.g. habitat, medicinal or dye use, food, or woody, herbaceous etc.). In cooperative groups, they can come up with a presentation style for sharing the information on their plant group with others. They can do a puppet show, an overhead presentation, a computer generated presentation, etc.
Invite other classrooms, parents, and community members into share in presentations.
Herbariums can also be placed in a very visible place in the school office, library, cafeteria, hallway, etc.
This is the beginning of your school's Natural History Museum with your students as docents.