Agriculture is the science of farming. It is a massive industry that literally keeps the world fed and which we couldn’t do without! The seed industry involves seed markets, costs and prices, regulation, plant breeding and more. It has evolved as the demand to feed the world’s population has grown. Identifying and classifying organisms is important and useful in both scientific and real-world settings. Farmers need to be able to identify seeds and be able to eliminate as many weeds as possible to ensure the greatest crop yield and to harvest only the intended plant. They must also be able to identify an invasive species, an organism that has a tendency to spread to a degree that causes harm to the environment. Knowing how to identify the plants in the field, and the seeds themselves, helps farmers eliminate any unwanted weeds, including noxious weeds which are injurious to agricultural or horticultural crops, natural habitats, humans, or livestock. Scientists and farmers may use a dichotomous key to help identify an organism by looking at characteristics such as size, shape, texture and color and choosing between alternative characteristics.
The Goal: In this activity you will identify unknown seeds by observing their characteristics and create your own key to classify objects.
Materials needed:
Ruler
Dichotomous Key
Envelope of Unidentified Seeds
Pencil
Tweezers (optional)
Hand lens or magnifying glass (optional)
How to use a dichotomous key!
“Di” is Greek prefix meaning two. A dichotomous key gives pairs an “either-or” choice that either directs the user to the next pair of choices or to the point of identification. Keys usually start with very broad choices and get more specific as they go down the list. For example, a key about birds might ask if the bird can fly or if it is flightless, and may then continue to ask about the size of the bird, shape of its beak, color of feathers, where it lives, etc. Here is a quick example to get you started:
Observe characteristics of these birds and answer the questions below to make an identification.
Size: about 5 to 9 feet
Flight? No
Size: about 5-6 inches
Flight? Yes
Size: about 1.8-2.6 feet
Flight? Yes
1A. Can the bird fly? If yes, go to 2. If no, then it is an ostrich!
2A. Is the bird smaller than one foot in size? If yes, then it is a downy woodpecker!
2B. Is the bird larger than one foot in size? If yes, then it is a raven!
Most dichotomous keys are more extensive than this example, but this should give you an idea of how to look at characteristics of the organism and answer a series of questions to identify it.
Instructions:
First you’ll need to sort the seeds. It will be helpful to sort them on a blank piece of paper or a paper plate. You might want to divide your paper or plate into sections to keep the seeds from getting mixed up. Look closely at each seed and observe its characteristics. Sort them according to size, color, shape, and texture. Some seeds of the same type may be a slightly different color. Once all seeds are sorted, use the dichotomous key included in this activity to help identify which seed types they are. Examine the seeds closely and read the key carefully as some seeds look very similar to others. Follow the questions on the dichotomous key until you’ve identified each seed type.
Now that you have experience identifying and classifying objects, you can create your own dichotomous key. Using seeds from the grocery story such as peas, beans, sunflower seeds, etc. you can create your own key for others to follow. Or, you can create a key to classify objects around your house or in your backyard. You can create a dichotomous key for just about anything you’d like to identify and classify, such as trees, insects or even video games!
More to Explore!
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You can save seeds and create your own garden. Watch this video to learn how:
Agriculture offers a range of career opportunities. This video explores many of these opportunities and describes how vital agriculture is for every person on the planet.