Dichotomous Key – Lowrie Ward

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4 responses to “Dichotomous Key – Lowrie Ward”

1. 

   June 22, 2025

   Steph the TA

   Hi Lowrie –

   This is a different take on the concept of a dichotomous key! And you did account for all four specimens. That said, it has a couple issues. Check out the Rubric for the assignment, to guide you.

   The couplets in question are meant to present a unique pair of related choices (which speak to presence or absence) on a single characteristic of the plant, and which either point to another couplet with a different but unique pair of choices or resolves to an ID. This key doesn’t do that – they all have Yes or No as their descriptor choices, which are not unique. In the case of #4, there is no second choice, and therefore it’s not dichotomous. Take a look in the next paragraph, and you’ll see what I mean.

   Also, each subsequent pair of choices are indented further and further in. Subchoices can be nested between the descriptors of the couplet, like so:

   A has glitter -> B
   B has rhinestones -> D
   C has sequins -> Plant Z
   C’ lacks sequins -> Plant W
   B’ lacks rhinestones -> Plant X
   A’ -> Plant Y

   or like so (though I find this a little harder to read):

   A -> B
   A’ -> Plant X
   B -> C
   B’ -> Plant W
   C -> Plant Y
   C’ -> Plant Z

   Does that make sense? If you get stuck please feel free to reach out to me. Try it again.
   Thank you!
   Steph

   Reply
2. 

   June 22, 2025

   Steph the TA

   Dang it! The machine did not preserve my formatting, despite the fact I put the spaces in! Let me try again!
   A has glitter -> B
   B has rhinestones -> D
   C has sequins -> Plant Z
   C’ lacks sequins -> Plant W
   B’ lacks rhinestones -> Plant X
   A’ -> Plant Y

   Hopefully that example works correctly!

   I LOVE technology, I LOVE technology, I LOVE technology!

   Reply
3. 

   June 22, 2025

   Lowrie Ward

   Hello, thank you for the feedback, I think the rubric makes more sense upon review.

   Reply
   1. 

      June 23, 2025

      Steph the TA

      Hi Lowrie –

      MUCH better!

      The paired branches of a dichotomy need to be differentiated slightly – in the keys for this class, it’s done by the addition of an apostrophe to the letter. So A and A’ (called A-prime) are the two branches of the A couplet. Same with the B and C couplets.

      There’s also a preference to say “Flower lacks petals” rather than “Flower has no petals” – it’s just more precise. A flower that you’d expect to have petals might be stripped of its petals for any number of reasons (bugs, children, nibbling deer) but saying the flower lacks petals tells the reader not to expect any.

      Thank you for resubmitting your corrections! I appreciate it!

      Reply