Identifying Organisms

Dichotomous Key

What: A dichotomous key is a series of questions, each with only two answers.

Who: ScientistsWhere: All over the WorldWhen: If you need to identify an unknown

organismWhy: To help identify an organisms genus and

species

Field Guide

What: A book using pictures and descriptions to help identify organisms.

Who: AnyoneWhere: All over the WorldWhen: If you need to identify an organism, and

know exactly what it looks likeWhy: 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……………...…………..62. a. Needles are over one inch long, in clusters…………..……3 b. Needles are one half inch or less………………………..43. 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………………………55. 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……………………………….88. a. Long slender leaves which droop down....…Weeping Willow (Salix babylonica) b. Leaves are less than twice as long as broad………………..99. 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……………...…………..62. a. Needles are over one inch long, in clusters…………..……3 b. Needles are one half inch or less………………………..43. 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………………………55. 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……………………………….88. a. Long slender leaves which droop down....…Weeping Willow (Salix babylonica) b. Leaves are less than twice as long as broad………………..99. 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!!