1a. Leaves are needle-like. . . . . . . . . . Plant 1
1b. Leaves are broad
2a. Flowers are predominantly purple. . . . . . . Plant 3
2b. Flowers are white or yellow
3a. Leaves are compound. . . . . . . . . . . . Plant 2
3b. Leaves are simple. . . . . . . . . . . . . . Plant 4
Hi Jheden –
Take another look at the Rubric that goes with this assignment. There are some points that were missed.
Your couplets will always come in pairs. That’s not the case here. Where is 2b?
For each branch of the couplet, there needs to be a single descriptor – a single feature to differentiate the two. One branch usually has that feature, while the other lacks it (if it doesn’t resolve to a plant).
At that point, you will either need to tell the reader what couplet to go to next, or tell the reader what plant the key indicates the branch points to.
Also, which branch resolves to which plant? The idea is to take any guesswork out of the choices.
Take a look at what your classmates have done – that’s one of the Module 3 assignments anyway – then revise your Key. It is likely that the indenting will be lost, but I will bear that in mind when I grade it.
Please try again.
Thank you,
Steph the TA
Well worded descriptions but it seems like the layout of the key does not include any sort of plant ID on the right side after the descriptions. The video we watched seemed to use A then A’ to couple the group options. But your words are great! Just did not direct me to the which plant to look for.
Hi Jheden,
I have a few thoughts on how your dichotomous key could be improved to make it even more helpful and easy to use.
The main goal of a dichotomous key is to highlight traits that help someone narrow down what species or plant they’re looking at. So, if a specific trait clearly identifies one plant from the others, it’s helpful to point that out right away, so the user knows they’ve reached the final ID point.
For instance, when we were looking at 4 different plants and only one had needle like leaves (which you mentioned). As soon as you highlight that trait you should label which plant it is. That way, the reader doesn’t have to keep going since they have found their answer. Also, it seems that dichotomous keys work best when the choices are in clear pairs, like “has flower petals” vs. “does not have flower petals.” If “no petals” is enough to identify the plant, label it right then. But if it only narrows things down, let the reader know where to pick back up to continue the process. For example,
has petals- D
Lacks petals- plant #
I hope some of this helps.
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