D. keys

It seems I am not the only one struggling with this assignment. I understand the concept of dichotomous keys but I find it very difficult to decipher certain plant characteristics through a photograph. For instance, even on the exercise with the two different species of violets, I keyed out different species with the Hulten and Cody keys. I had no reference point for whether the rootstock of the violet was ‘slender’ or ‘stout’. I was also confused by the ‘bearded’ part. It seemed that the petals were slightly hairy and I would assume that would mean it had a ‘plant beard’ but apparently not. I found the Cody key much more straightforward than the Hulten.


Classmate, Rachel, and I decided to try and work on formulating the dichotomous keys together because we were both pretty confused. This is what I had in my notes and I’m about 90% positive I didn’t get the species correct. However, I will say that this exercise gave me a LOT better idea about what dichotomous keys are and that there are many different paths you can take when making your own. I could appreciate that Cody and Hulten took different perspectives in identifying the plants. I found that Cody’s was a bit simpler.


Dichotomous keys (1)


  1. Thanks Rebecca,
    sorry for not being more explicit. I would not expect you to identify the plants from the pictures unless you have all the characters needed to do so. In this exercise you were not asked to write a dichotomous key that would identify the bins to a particular species of plant, rather you were to write a dichotomous key that would separate the bins.

    Your key works very well, so look at it again with those points in mind, and revise your key.

    You would want to write the key from the perspective of dividing the bins up in a sequential manner, not necessarily writing a description for each bin, that is needed to write the key, but you can just take the characters that most easily separate the bins from one another.

    Gymnosperms vs. angiosperms, white petals vs. purple petals vs. lacking petals, and so on. It is all in your document, you might just want to write it in the couplet form as was done for the violets and for the spruce.

    1. Avatar photo rchandler

      Oh okay! That’s what I initially though the assignment was but thought that sounded too simple. oops.

      So instead it would look something like
      A. Tree
      —– B. Conifer
      ———- C. terminal buds
      —– B. Deciduous
      ———- C. broad pubescent leaves and long catkins
      A. White flower
      —– B. Four petals
      ———- C. 3-4 stamen
      A. Purple flower
      —– B. Six petals
      ———- C. numerous stamen

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