CHAPTER 15
PLANT IDENTIFICATION
REVIEW QUESTIONS
1. What is identification?
Identification is the process of associating an unknown entity with a known entity. It is a judgment that some
perceived object is similar enough to a known entity that it falls within the criteria of belonging to the same class as
the known entity.
2. Describe how identification is used in your everyday life.
We use it for the ability to recognize, for example, edible from toxic or friend from foe has evolved via strong selective
pressure.
3. What is a diagnostic characterization (= diagnosis) and how is this important in identification?
Diagnosis is a listing of all the features of a taxon that distinguish it from all other taxa.
4. What is the difference between holistic and analytic mental processing?
Holistic mental processing is that in which an object is viewed or emphasized as a whole.
Analytic identification entails breaking down or subdividing the whole object into parts,
5. What are the difficulties with identifying cultivated plant taxa?
Cultivated plants can be native to any region so a reference that includes the correct taxa can be hard to find, they
may include a great number of cultivars, hybrids or other breeds that are continually being introduced and may be
quite different in appearance from an original native species.
6. Name five methods used to identify plant taxa, citing the advantages and disadvantages of each.
Taxonomic keys – advantage-practical, disadvantage-specimen may lack data used in key
Polyclave key – advantage-permit the use of a limited subset of information to narrow down the possibilities,
disadvantage-they have generally been written only for a limited number of taxonomic groups.
Written description – advantage-good method of determining whether the range of variation of the unknown plant
corresponds to that listed in the description of a known plant, disadvantage-reading all of the written descriptions of a
flora is impractical
Specimen comparison – advantage-many features of a plant are visible, disadvantage-herbarium specimens may not
be correctly identified.
Expert determination – advantage-expert will usually know the taxa of that group over a wide geographic range,
disadvantage-time-consuming, specimen usually must be sent away for identification.
7. What is a dichotomous key?
A dichotomous key is the most common type of key and consists of a sequence of two contrasting statements, lead and
couplet. Identification proceeds by choosing between the contrasting leads of a couplet.
8. What is a couplet? A lead?
Lead is each statement in the dichotomous key. Couplet are two leads together.
9. What precautions should be made in using a dichotomous key?
All parts of both leads should be read before deciding which fits the plant best.
10. What is the difference between a natural and an artificial key?
Artificial key: sequential groupings of the key do not intentionally reflect natural groups; their goal is to most easily
and efficiently identify a given taxon, with no concern about classification into other groups.
Natural key: diagnostic features are used to delimit “natural” groups, which are usually formal taxa.
11. What is a polyclave key?
A ployclave key consists of a list of numerous character states, whereby the user selects all of the states that match the
specimen. Based on which of the character states is a match, the correct taxon can be determined.
12. What are the advantages and disadvantages of a polyclave key?
Advantages: they permit the use of a limited subset of information to at least narrow down the possibilities; the
specimen cannot be absolutely identified, its identity may at least be narrowed down to a few alternatives, which can
then be checked by other means
Disadvantages: is their availability; they have generally been written only for a limited number of taxonomic groups.
13. How are images important in plant identification?
Images, in the form of a photograph or drawing, can be used to clarify the meaning of contrasting characters or
character states. Images of the taxa themselves (showing their distinguishing features) are particularly useful in
checking the accuracy of an identification. In fact, images alone may be used in constructing a key.
14. Name ways, other than a taxonomic key, to identify a plant specimen.
Written description, specimen comparison, expert determination, image comparison.
15. What is a synoptic collection and what is its advantage in plant identification?
Synoptic collections generally house one specimen of each taxon for a given region. If a taxon can be narrowed to a
smaller group, such as family or genus, a quick search through a synoptic collection for that region may often allow
for site identification of the unknown.
16. State the practical steps made in identifying a plant specimen.
Know the general characteristics of several families ahead of time. Have an idea as to the general group within a
family to which the taxon belongs. Once a determination is made, re-check your determination with all available
means. Send off specimens for expert determination if needed. Always be conscious of the possibility that the
identification process can point to a new taxon.