Dichotomous Key Sample HW Module 2

Module 2

Dichotomous Key sample

Laura Emerson

For some reason, the post did not preserve the increasing indentation of each lettered section.


Bin 1:

A Tree with needles   …go to B

A1 Tree without needles… go to x (not demonstrated)

B Tree with cones … go to C

B1 Tree without cones… go to x

C   Tree with budding tips… go to D

C1 Tree without budding tips … (does that even exist? Or did I miss the   point of the photo?)

D Tree with something distinctive about its bark (cannot tell what).   … go to somewhere

D1 Tree lacking that something   (go to x)

Bin 2:

A Flower with four petals … go to B

A1 Flower with other … goXXX

B Flower pendulous … go to C

B1 Flower upright … go xxx

C Flower white… go to D

C1 Flower color other …

D Leaf oval … go somewhere

D1   Leaf other shape… go xxx

E Trichomes on the stem… go to xxx

E1 No Trichomes on the stem… go toxxx

Bin 3:

A.Flower blue/purple… go to B

A1.   Flower other color… go to xxx

B. Multiple stamens… go to C

B1.   Few stamens… go to xxx

C. Multiple pistils… go to D

C1.   Few pistils… go to xxx

B 4:

A Leaf elliptical (or is that lanceolate?) … go to B

A1 Leaf not that above… go elsewhere

B Leaf hairy… go to C

B1 Leaf not hairy … go elsewhere

C Multiple  stamens, fused to ovary … go to D

C1 Few stamens … go to xxx





  1. Laura,
    for this exercise, you would just consider all the plants in one plate/ bin to be one plant and the different images in each bin represent different features of each plant, but one bin equals one plant. So when constructing your key you could select one or multiple features of each bin to construct your key. This was meant to be a simple exercise of realizing that you have to organize your data before you can make the key, and that there are different solution to the puzzle. You could start out with dividing the bins up by those with needles, those that are lacking needles, those that have catkins and those that lack catkins, etc. You do not need to account for all the features represented in each of the bins in your key. I hope this makes sense. It looks like you meticulously went through the images trying to incorporate each feature of the plants, but that would really only come into play if all four bins where from the same genus and thus all plants were very similar, but here we were lucky and only had some major categories that allowed us to divide the bins up easily.

  2. Melissa Tuttle

    I really enjoyed how detailed your key is! I was easily able to follow your flow. I wish I could have seen your final conclusions for each bin.

    Your Classmate
    Melissa Tuttle

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