Pulling winter weeds in the school garden can be a good lesson in the documenting all the plant species found within a specified area. Collected specimens can then become part of the schoolyard herbarium, an indoor dried garden representing the plant diversity in the outdoor growing one.
Start slowly by looking at one plant at a time. For example, students might find henbit, Lamium amplexicaule, a common winter weed in South Carolina. The square green to purple stems hold kidney-shaped leaves with toothed margins. The annual weed produces nectar rich purple two-lipped flowers by early spring.
Whatever weed is the starting point, as students observe the plant on campus, they will record the following data in field notebooks: date of observation, location of plant in schoolyard, soil type, nearby plant associates, height of plant, flower color and scent, and identity of insects visiting plant. South Carolina wildflower and weed field guides will help identify the specimen. Students should take digital photographs of the plant, which also captures its habitat. Observations and photographs will become part of the documented history of each specimen.
On subsequent outings have students sketch the plant and tint the sketches with watercolor pencils. Sketching detects details words miss and tinting adds another identity clue.
A field trip to the nearby herbarium is a must for understanding how to establish a schoolyard herbarium. In the Midlands call the A.C. Moore Herbarium on the University of South Carolina campus to schedule a guided tour. On the day of the trip dig up one specimen, from roots to flower, to contribute to the herbarium collection. Bring the data students collected on the specimen too.
Students will be able to check the accuracy of their specimen’s identity by comparing it to voucher specimens at the herbarium. Your specimen will also be used as an instructional model to show how botanists preserve, label, mount, and file plant specimens on a daily basis as part of their botanical research.
The herbarium curator, John Nelson, or his staff will use your plant to demonstrate the use of a plant press. The specimen is placed between layers of corrugated cardboard (allows airflow), blotting paper (absorbs moisture) and newspaper (holds plant material) before anchoring all between two rigid wooden lattice frames and tightening two straps around the entire plant press. Students can sketch the process in their notebooks before moving to the drying room. An oven the size of an upright refrigerator set at 110 degrees is the next step in the preservation process. The plant press sets upright in the oven for one week and is creating a two-dimensional specimen from the three-dimensional original.
Then the dry specimen will be mounted with glue onto acid-free cotton rag paper.
A label with the field data collected by students will be attached to the page.
The page will be filed in airtight cabinets by taxonomic group and geographic region.
Students will tour the “plant morgue” where their specimen will become part of the historical botanical dried garden.
Back in the classroom your junior field botanists are now ready to construct plant presses, plan the location for the schoolyard herbarium archive, and continue the floristic survey and creation of a schoolyard herbarium for future explorations.
Arlene Marturano is an educator, consultant, master gardener, and freelance writer. Read more of Arlene Marturano’s garden writings at suite101.com and www.scgardenlearning.com