I wasn’t sure which dichotomous key would be easier to follow, so I made two with slight differences. They are separated by the line in the middle of my screenshot. Does one make more sense than the other?
Dichotomous Key
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The second one was easier for me to follow since characteristic A just talked about needles. The first one was a little harder to see the matching pairs of characteristics (has vs lacking). I was able to get to the correct ID following both keys. The indents worked great and allowed me to follow the characteristics. I think traditionally each pair of characteristics should have both a regular and a prime letter (ex. A and A’) all the same case. “Plants lack flowers with petals” would be more clear if it just said “Flowers lack petals” because I wasn’t totally sure if the plants lack both flowers and petals, or just petals. That could just be my personal opinion though. I’d place a “B” at the end of the “Plant lacks needles” line just so it is super clear to go to that line next. All of the characteristics worked great for telling the plants apart and getting me to the correct plant 🙂
I should also say that I liked that the key was simple and straightforward. You were able to find the characteristics that distinctly defined each plant and use them to make it easy for the reader. I had trouble not over describing them myself.
Good feedback, Bridgett!
BTW, you are correct about “Flowers lack petals” being clearer. Simple really is best! And you gave some great feedback to Isabella. Kudos!
Thanks so much for the great feedback, Bridgett! I appreciate your suggestions.
Hi Isabella!
The second one, for a few reasons – the first being that the couplets are paired, which they aren’t in the first example (there is no B’).
You’ll need to look at other students’ examples for an assignment this week, and one thing you’ll notice in most are how the pairs in the couplets are organized – e.g., the A Couplet has A and A’ – and each branch has a related characteristic: one has it while the other lacks it, or has a differentiating feature about the same characteristic (has red petals, has blue petals. Your C couplet is a great example of this last.
If your couplet branch does not resolve to a plant (A’ = Plant lacks needles – ideal, btw), then you will want to direct the reader to go the next appropriate couplet. You did it with your B to C branch, but not with the A’ to B branch. Basically, you’re trying to take the guesswork out of everything.
The indenting of the second example is good, you resolved to all four plants in the exercise, and your descriptors are unique and obvious. Other than a little labeling and pointing, this second key works!
If you want to risk it, you can go ahead and make the corrections to your key. You *might* lose the indenting, though – WordPress has been very fussy in the last couple of days. Please let me know before you do anything!
Good job!
That all makes sense. Thanks so much for the detailed critiques. This was super helpful for me in grasping dichotomous keys better. Regarding your last comment, I’ll just leave my first key as it is since the second key works. Thanks again!