Dichotomous key

1A) Plant contains flowers…  go to 2

1B) Plant contains a cone…  Plant 1

2A) Plant has opposite leaf attachment… Go to 3

2B) Plant has whorled leaf attachment… Plant 3

3A Plant has liner leaf shape, with smooth leaves… Plant 2

3B Plant has elliptic leaf shape, with hairy leaves… Plant 4

Comments

3 responses to “Dichotomous key”

  1. Steph the TA Avatar
    Steph the TA

    Hi Matt –

    Take another look at the Rubric for this exercise – you missed a couple of criteria, and it impacts your grade, so you will want to resubmit.

    On your first couplet: I agree that Plant 1 contains a cone (a real one, vs. something like an alder cone, which is really a catkin) – however, there is a much more basic feature about that picture that helps you identify Plant 1 even when it’s too young to bear cones, and still differentiate it from the other three plants. I would use that feature instead.

    On your second couplet: I hadn’t actually noticed the leaf attachment for Plant 3 – I was so fixated on that showy flower that I completely missed it. That is a really great observation!

    On your third couplet: For this exercise, each line in a couplet should have a single, unique characteristic. Can you see the leaves well enough for Plant 2 to describe them? Is there a more basic, more obvious characteristic you can use here?

    If you feel stuck, go ahead and email me (szaborac@alaska.edu). And please resubmit.

    Thank you,
    Steph

  2. Matt Shavlik Avatar
    Matt Shavlik

    1A) Plant lacks needles … go to 2
    1B) Plant contains a needle… Plant 1

    2A) Plant has opposite leaf attachment… Go to 3
    2 B) Plant has lacks opposite leaf attachment… Plant 3

    3A Plant has flower petals… Plant 2
    3B Plant lacks flower petals… Plant 4

  3. Steph the TA Avatar
    Steph the TA

    Hi Matt –

    Much closer! I’m going to give you credit for the indent, because I just saw the system strip indenting out of another post. Just remember that each couplet indents a little further than the preceding one.

    The descriptor regarding leaf attachment for 2A is not correct – they not opposite, they’re something else (can you name it? I know the leaves are tiny in Plant 2, and it’s a bit vague in Plant 4, so take a really close look). Coincidentally enough, your 2B would still work (2B would become Plant lacks this kind of leaf attachment), since that leaf attachment is whorled!

    Thank you for trying it again!

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