Dichotomous Key

Report
Identifying
Organisms
Dichotomous Key
What: A dichotomous key is a series of
questions, each with only two answers.
Who: Scientists
Where: All over the World
When: If you need to identify an unknown
organism
Why: To help identify an organisms genus and
species
Field Guide
What: A book using pictures and descriptions to
help identify organisms.
Who: Anyone
Where: All over the World
When: If you need to identify an organism, and
know exactly what it looks like
Why: To identify the name of an organism
Field Guide and a Dichotomous Key
Field guides are very different than
dichotomous keys. For example, field guides
use pictures and dichotomous keys use
questions to identify an organism. Field guides
are harder to use because you have to decide
which organism throughout the whole book
looks exactly like the one you are trying to
identify.
Field Guide
Dichotomous Key
or
Field Guide?
If you said Field
Guide, you were
right!!
Dichotomous Key
or
Field Guide?
1 a. Leaves are evergreen, thin, needle-like…………...………..2
b. Leaves are broad, deciduous……………...…………..6
2. a. Needles are over one inch long, in clusters…………..……3
b. Needles are one half inch or less………………………..4
3. a. Needles in clusters of three………….Pitch pine (Pinus rigida)
b. Needles in clusters of five…… Eastern White Pine (Pinus strobus)
4. a. Needles scale-like, sharp, cover twigs....Eastern Red Cedar (Juniperus
virginiana)
b. Needles protrude from the twigs………………………5
5. a. Needles flat, rounded tips in two rows along twig….Eastern Hemlock (Tsuga
canadensis)
b. Needles in whorl around the stem…...……White Spruce (Picea glauca)
6. a. Compound leaves divided into 7 leaflet…....White ash (Fraxinus americana)
b. Simple leaves.………………………………..7
7. a. Lobed, rounded leaves with 7 to 9 lobes…...…..White Oak (Quercus alba)
b. Toothed leaves……………………………….8
8. a. Long slender leaves which droop down....…Weeping Willow (Salix babylonica)
b. Leaves are less than twice as long as broad………………..9
9. a. Leaves have an elliptical shape………American Beech (Fagus grandifolia)
b. Leaves are toothed and lobed…..………Sugar Maple (Acer Saccharum)
If you said
Dichotomous Key,
you were right!!
1 a. Leaves are evergreen, thin, needle-like…………...………..2
b. Leaves are broad, deciduous……………...…………..6
2. a. Needles are over one inch long, in clusters…………..……3
b. Needles are one half inch or less………………………..4
3. a. Needles in clusters of three………….Pitch pine (Pinus rigida)
b. Needles in clusters of five…… Eastern White Pine (Pinus strobus)
4. a. Needles scale-like, sharp, cover twigs....Eastern Red Cedar (Juniperus
virginiana)
b. Needles protrude from the twigs………………………5
5. a. Needles flat, rounded tips in two rows along twig….Eastern Hemlock (Tsuga
canadensis)
b. Needles in whorl around the stem…...……White Spruce (Picea glauca)
6. a. Compound leaves divided into 7 leaflet…....White ash (Fraxinus americana)
b. Simple leaves.………………………………..7
7. a. Lobed, rounded leaves with 7 to 9 lobes…...…..White Oak (Quercus alba)
b. Toothed leaves……………………………….8
8. a. Long slender leaves which droop down....…Weeping Willow (Salix babylonica)
b. Leaves are less than twice as long as broad………………..9
9. a. Leaves have an elliptical shape………American Beech (Fagus grandifolia)
b. Leaves are toothed and lobed…..………Sugar Maple (Acer Saccharum)
Dichotomous
Key or
Field Guide?
If you said
Dichotomous
Key, you were
right!!
Dichotomous Key
or
Field Guide?
If you said Field
Guide, you were
right!!

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