Plant Taxonomy

This multi-part lesson plan was developed by Gregory Shenk of the Greater Hartford Academy of
Math and Science in Hartford. Students first collect plant specimens and mount them so they can be preserved in perpetuity for research and education. Then they will become familiar with using online herbarium data and will respond to questions about the meaning of the information they find in the "Virtual Herbarium."

I – Making collections

Background:  Throughout the 1800s and into the mid-1900s, academic institutions of all sizes used to maintain collections of preserved organisms as sources of material for use in the classroom and research.  In fact, it was not uncommon for individuals to maintain private collections for their own study and leisure.  With the dawning of the molecular revolution, changes in the culture of biological research have led to an increasing emphasis on experimentation and data collection in a laboratory environment.  One of the unfortunate (and unintended) consequences of this shift has been a slow decline in the number and quality of biological collections at many institutions.  Fortunately, collections at some of the larger institutions have been able to survive and in some cases even expand.  The University of Connecticut is one such institution. 

Much of the expansion of collections at the University of Connecticut has been a consequence of absorbing the collections from many smaller institutions as they made room for more technically oriented biological science programs.  There can be a great deal of valuable data recorded with these specimens and many questions can be answered using this data.  In order to keep the data up-to-date, new collections need to be made and archived. 

While organisms of all kinds can be collected and preserved for long-term storage, this exercise will focus on botanical collections.  You will be expected to collect, press, identify and mount a collection of 15 plants.  Your collections will be submitted to the herbarium at the University of Connecticut and will become part of a collection that is available for researchers around the world to use.  Your name and the name of your institution will appear on collection labels so students half a world away may one day be using your collections in their own research!

Instructions: Find a location where you would like to collect plants and obtain permission from the landowner and collection permits (if applicable).  You should have a notebook to record field data on your specimens, a trowel for digging out plants by the roots and hand pruners for collecting woody branches.  You will want to record as much information in your notebook as possible at the time of collection (see label below to see what you will want to record).  You needn’t identify the plant (but it won’t hurt) at the time you collect each specimen, but you should record the collection number, the date collected, and a description of the location where the plant was collected.  The collection number for each specimen is unique and most collectors start at 1 (so accessions with four- and five-digit collection numbers reveal a collector who has been very busy!).  The date is very important as the developmental stage of the plant at the time when collected may reveal changes in environmental conditions over time such as global warming.  The description of the collection site ought to be as specific as possible.  If you record the name of the property, it may be difficult for a botanist to pinpoint the location in 150 years if the name is no longer in common usage.  On the other hand, latitudes and longitudes don’t change.  In the past, these were gleaned from topographic maps.  Now many collectors carry handheld GPS units.  Also, try to record physical characteristics of the site such as soil textures (e.g. sandy, silty, heavy organic layer, etc.) and moisture regime (dry upland, boggy area, flowing stream, lake), and the names of as many of the plants as possible that you find surrounding your specimen.

It’s actually best to identify the plant while it’s still fresh, but most botanists collect several specimens while in the field and transport their specimens to a common location where they can identify and press them.  To keep the plant in its best condition while you are collecting in the field, you should place a piece of masking tape around the stem with the collection number that corresponds to the data you’ve recorded in your field notebook and enclose the plant in a large plastic bag.  When you’re finished collecting and ready to identify and press the plants, you should remove them one at a time from the bag(s) and place them in a plant press (see below, although a couple of pieces of plywood and rope work just as well) as soon as possible after you finish the identification.  The plants should be dried as thoroughly as possible to avoid molding and will dry more quickly if the press can be stored in a hot attic or a car trunk.



After completing the information on the collection label and drying the plant in a press, you will need to mount the label and the plant on a herbarium sheet.  A mounted specimen is illustrated below.  The best method for mounting specimens is to spread a diluted museum-quality acid-free adhesive on a 16 x 24 sheet of Plexiglas (as an inexpensive alternative, try placing overlapping strips of plastic wrap on a counter-top) with a paintbrush and then lay the plant down in this adhesive film.  First mount the specimen label by placing it in the glue, then transferring it to the herbarium sheet. Traditionally, labels are applied in the lower right corner of the herbarium sheet. Then repeat the procedure with the plant, transferring in an orientation so the whole specimen fits on the herbarium sheet.  Spread a sheet of wax paper over the specimen and label and place a board on top to hold the plant down while the glue dries. After a day or two, the adhesive should be dry and the specimen can be stored until you’re ready to turn in the collection for a grade. (See the rubric for information on how collections will be graded.)
       Additional information on collecting and mounting plant specimens is available in a publication from the University of Florida Herbarium.


Plant taxonomy II – making digital connections

Background: As the smaller collections were absorbed into larger collections at fewer institutions, the scientific utility of the records contained in these combined collections improved.  Many of these collections are now being digitized and, consequently, the data associated with the specimens can be made available to anyone any place in the world with an internet connection.  The herbarium at the University of Connecticut has one of the most comprehensive collections of New England plants in the region and many of the specimens have been digitized.  This exercise has been designed to familiarize you with the electronic resources that the “CONN” herbarium has made available to you through their online database.  You may want to conduct this exercise while your plants are drying in the press.

Using digital data: Pay a “virtual visit” to the University of Connecticut’s herbarium (http://bgbaseserver.eeb.uconn.edu/) and generate a distribution map for one of your species.  Select “Virtual Herbarium” and conduct a “simple” query using the genus and species name from one of your specimens.  At the top of the results page, click on “Map these results with Berkeley Mapper” to get a sense of where your species occurs.  Several markers will probably appear on the map that you’ve just created.  Click on one of these markers and follow some of the hyperlinks to see what kinds of valuable data can be gleaned from this database.  You can zoom in or out using the vertical scale bar on the left side of the map but the results are often unsatisfying.  It’s better to use the “zoom by box” (a magnifying glass icon) tool above the map.  You also can toggle between the different background options (map, satellite, hybrid, terrain, etc.) in the upper right portion of the map. 

Next, click on the hand tool and drag the map until you can see your own neighborhood.  See if there are any accessions of this species that have been collected near your house.  Now click back to the Virtual Herbarium link and do an “advanced” query.  In the “locality” field, type the name of your hometown.  This will bring up all of the accessions for all species from your neighborhood for which data has been digitized.  You might be surprised to find out how few species are listed in your neighborhood.  Your specimens may be the first from your local area that will become digitized – in which case your name will appear to others who are doing the same virtual search in the future!  After playing with the features of this mapping program, answer the questions below.

  1. To see just how important your collections may become, go to the “Advanced” Query and enter the name of your town to map accessions of all species found in your immediate neighborhood.  Zoom in on one or more of the sites that are closest to your home.  Click on one of the markers and toggle through the accessions that have been collected there.  How many are there? 
    2. Why might there be more specimens recorded in one location than another?

    3. Locate the accession record for Gentiana clausa at Northwest Park in Windsor.  Who collected it?

    4. How many accessions does the herbarium have from this collector?

    5. From this record it is possible to determine that, at a minimum, this individual has collected at least how many specimens?

    6. When was the specimen collected?

    7. Offer two reasons why it should matter.

    8. How precise is the latitude and longitude that is recorded for this species?

    9. Not all of the locations recorded for this species are so precise. What might account for differences in the precision of these numbers?

    10. Map the locations of Poa pratensis.  How many locations did you find?

    11. If this is a common grass found in many
Connecticut lawns (it is), why isn’t it mapped in more locations?

    12. Look up the genus Celastrus.  Notice that some accessions have only a “label name” and some have the additional field “Filed in CONN as.”  What do you think could explain these differences among accessions?  

    13. While you will see records for more than one species of Celastus, one species clearly has the greatest number of records.  Which one is it?

    14. Try to come up with at least one explanation for this on your own and then look the species up online.

    15. What is an invasive species?

    16. Go back and do a general search of accessions from your town.  View the records for at least five different species that were collected in your neighborhood.  When you view the individual records for some of these accessions, you will probably see the word “introduced” under the camera icon.  This means the species is a relative newcomer to your region (and was probably brought here by humans – either purposely or accidentally). How many of the accessions that you viewed from your town were “introduced?

    17. What does this mean about the condition of natural areas in Connecticut and does this make you concerned?  Why or why not?

    18. What other impacts may this change in the composition of the pre-colonial ecosystem have?

    19. The colonists were not the first humans in New England and archeological evidence in other parts of the world show humans have had big impacts on ecosystems wherever they’ve been.  Why might humans change the landscape and what might some of these changes in the plant communities before Europeans arrived have looked like?

    20. Humans are not the only biotic force that changes ecosystems.  Beavers can have substantial impacts on plant communities as well.  Abiotic fluctuations such as those associated with climate can also have a large impact.  Use your favorite internet search engine to look up “pollen stratigraphy.”  What is this and how would the information it reveals compare to the data in CONN’s digital collections?