Wk 6: Gymnosperms

The first topic today is gymnosperm identifications. This assignment has 3 parts:

1. Read background about dichotomous keys and traits of gymnosperms used in dichotomous keys. Some of this will be review because you used a dichotomous key to identify species based on twigs.

2. Complete a Blackboard quiz on the background information. You can retake the quiz. Once you score 75% or higher, you will be be given access to a set of images of gymnosperms that you will need to take the remaining quizzes. The photographs and links to the Blackboard quizzes are in a sub-folder within this week's folder. You will then use the linked dichotomous key to identify the gymnosperms. Record your steps in the key using a separate Blackboard quiz for each specimen (as you did for the twig id).

3. You need to find one gymnosperm from a natural area and take photos according to the instructions. Bring your ruler because leaf size is an important trait. Also make sure you have an identifying sticker in your photograph, so I know it is your own photograph. I suggest finding a pine tree because the species needs to be different than the ones for which I provided images. I did not provide images of most common pine trees. Identify the gymnosperm using the dichotomous key (in addition to your photographs, I suggest bringing a branch back with you - it's easier to do using a specimen in front of you).

You will document the gymnosperm that you found and identifying by creating a journal entry with an inserted photograph. You will list all the steps in the key that lead to your identification, and provide some information about the species.

** Assignment hint: while you are responsible for using the dichotomous key to identify the species, you are also allowed to check your identification by uploading photos to INaturalist.**

Students next read this background on taxonomy, dichotomous keys and gymnosperms

Background document about taxonomy, dichotomous keys and gymnosperms is linked here.

Next students take a Blackboard LMS quiz on which they need to demonstrate knowledge of background material (basic characteristics of gymnosperms, taxonomic hierarchy, use of dichotomous keys). Once student passes quiz with 70% or higher score, they can move on to next part of assignment.

Gymnosperm Identifications

Students use the gymnosperms identification key for the Southeast USA linked here to identify gymnosperms whose images we provide.

We chose 6 gymnosperm species from across major groups (and provided images taken in the field or from herbarium specimen). We will share the document with images with instructors from other institutions by email.

Each identification is structured as a Blackboard LMS quiz. Each quiz question is multiple choice with each answer being one of the two choices in the dichotomous key. The next question always starts with the answer to the previous question and proceeds with the two choices from the next couplet. This prevents students from getting lost and straying down a path of irrelevant questions. Quizzes are set to not allow backtracking. This structure keeps the students on track, such that if they make a mistake in an early couplet, they are redirected back to the correct couplet for the next question.

In addition to the 6 specimen whose images we provide, students are required to find a naturally growing gymnosperm, photograph it, and key it out using the guide. The specimen is not allowed to be planted (but students either can't tell or just ignore this) because the key doesn't cover cultivated species. The specimen also must be a different species than the ones they already keyed out, so the instructor should avoid using very common species for the species whose images the instructor providers.

Students submit images of the specimen they photograph as a journal assignment in Blackboard LMS.

Here are the instructions provided to students:

Summary

Find, photograph and identify one gymnosperm from a natural area (not a yard or other area that has been landscaped).

Selection of plants

Choose a gymnosperm species that meet the following conditions:

• 1. It should come from natural areas & not be intentionally planted (there are too many planted species that are exotic and not in our key.)

  2. The species must be new - not a species you already keyed out using the provided photographs.

  3. I suggest finding a pine (pines have needle-like leaves in fascicles) because there are common ones not included in the set of gymnosperms identified by photographs.

Photographs

Provide 2 or more photographs of the gymnosperm

• • One photo should be of the plant as a whole (or as much of the plant as you can photograph)

  • One photo should be a close-up of a branch with details of leaves apparent

  • Other photos can show bark, cones, or other useful features

Identify the specimen using the key

Use the Key to Gymnosperms linked here to identify the gymnosperms photographed below:

In your responses, do the following:

1. list each step you follow in the key (you can copy and paste the list of steps from the online key into your answer sheet).

2. Include the plant family, the common name and scientific name of the plant. Properly format each name. For example, a particular tree has the common name lodgepole pine, family Pinaceae, scientific name Pinus contorta. See the following example.

Example identification:

Leaves needle-like or scale-like, and simple

Leaves needle-like

Needles attached singly

Needles two-sided

Apices of needles pointed

Needles alternate

Needles 1 mm. or more wide, 10-80 mm. long, evergreen

Needles 1-3 cm. long, flexible; soft to the touch

Family: Taxaceae

Common name: Canada yew

Scientific name: Taxus canadensis

Submission of your photographs and identification

Submit your photographs and identifications in the gymnosperm identification journal.

In your document, start by INSERTING the photographs. Then include the steps in the key and identification of that species. Do not attach any documents, type or insert the information directly into your journal entry.

Gymnosperm images we provide

Gymnosperm 5