Dichotomous Keys Home practice

Dichotomous Keys Now that we know how organisms are classified. We know some of the characteristics that make up each Kingdom of the Classification System. Let’s Put It to work! And try to find the names of organisms by their characteristics!!!

There are many ways to find the names of organisms by looking at their characteristics. One way to do that is using a – DICHOTOMOUS KEY A system of reading the characteristics in an either/or style.

Example of a diagnostic dichotomous key for some eastern United States oaks based on leaf characteristicsUnited States oaksleaf US Oak Leaf Key 1. Leaves usually without teeth or lobes: 2 1. Leaves usually with teeth or lobes: 5 2. Leaves evergreen: 3 2. Leaves not evergreen: 4 3. Mature plant a large tree — Southern live oak Quercus virginianaSouthern live oak 3. Mature plant a small shrub — Dwarf live oak Quercus minimaDwarf live oak 4. Leaf narrow, about 4-6 times as long as broad — Willow oak Quercus phellosWillow oak 4. Leaf broad, about 2-3 times as long as broad — Shingle oak Quercus imbricariaShingle oak 5. Lobes or teeth bristle-tipped: 6 5. Lobes or teeth rounded or blunt-pointed, no bristles: 7 6. Leaves mostly with 3 lobes — Blackjack oak Quercus marilandica 6. Leaves mostly with 7-9 lobes — Northern red oak Quercus rubraBlackjack oakNorthern red oak 7. Leaves with 5-9 deep lobes — White oak Quercus albaWhite oak 7. Leaves with shallow lobes — Swamp chestnut oak Quercus prinusSwamp chestnut oak A E B F C G D H

Making your own Key Look for characteristics that separate the “Wacky People” into groups, ie: how many feet or eyes they have. Do they have hair? What is their body shape (round? Square?) Once they are grouped, separate each group into smaller groups based on characteristics in that group. Go through all characteristics till you have only one “wacky person” with that characteristic. NAME EACH “Wacky Person”!!! – Give them a Genus and species name. – ex: Sparticus flier – make the name funny and appropriate for class.