What Is the Identification Key of a Dandelion?

Plant Profiles

• The U.S. Department of Agriculture Plants Database offers standardized plant profiles. It covers vascular and non-vascular plants. Dandelions are vascular because they have a system of vessels that delivers nutrients and moisture from one plant part to another. The heart of the profile is its classification tree. It is a step-by-step analysis of a living thing's lineage from its kingdom, which for plants is Plantae, on down to its species, which is Taraxacum officinale for the common dandelion.

Dandelion Classification Tree

• After kingdom, comes "sub-kingdom." Dandelions are in the sub-kingdom of vascular plants (Tracheobionta). Next comes the "superdivision," which is the seed-bearing plants (Spermatophyta). Dandelions and cone-producing plants (Gymnosperms) both share this category. But then the dandelion branches off into the flowering plants "division" (Magnoliophyta). Classification then narrows down to "class." The dandelion is a dicotyledon (class Magnoliopsida), which means it has a more sophisticated pollination system than a monocotyledon (class Liliopsida), such as a Turk's-cap lily. From here, the dandelion fits into subclass Asteridae, order Asterales and the aster family (Asteraceae or Compositae). The classification tree then identifies its genus as Taraxacum -- the many kinds of mostly invasive, buttery yellow flowers referred to as dandelions. The name on the last branch adds the descriptor "officinale" to the genus name to identify it as the most common species.

Dichotomous Key

• A dichotomous key uses a process of paired statements called couplets that concern traits and eventually lead to identification. When first learning how to differentiate organisms and objects using a dichotomous key, a student might receive a disparate list, such as "rock, tin can, cat and insect." The first couplet might say, "1. a. Organism is living, go to 3; 1. b. Organism is not living, go to 2." After observing that the object doesn't breathe, the answer is "1b," which rules out cat and insect. Moving on to step 2, the student chooses whether the object is metallic or nonmetallic. If the answer is "non-metallic," then tin can is excluded and the answer is "rock."

Dandelion Dichotomous Key

• Supposing that a dandelion is unfamiliar but obviously a plant, the first couplet in its dichotomous key might be "1. a. Plant grows in grass, go to 2; 1.b. Plant doesn't grow in grass, go to 3." This might lead to "2. a. Plant has long leaves, go to 4; 2.b. Plant has tiny leaves, go to 5." The series of couplets would continue until the dandelion is described as a flower that grows in grass and has bright yellow blossoms, globe-like seed heads and long leaves with deep serrations.