Understanding the Keying Process

For centuries, plant enthusiasts have prepared various kinds of keys. These keys have taken many forms, from the earliest tabular types to multichotomous to dichotomous to random access, etc. The following is a brief overview of two key types used for identifying plants, as well as instructions for utilizing the key found within BONAP's TDC.   Traditional Keys Traditional dichotomous keys used for identifying vascular plants, especially those designed for large geographic areas, such as states, regions, or continents, generally follow hierarchical multi-stepped prescribed processes, forcing the user to select morphological characters in a predetermined order. The hierarchy generally begins with a family key, followed by generic and specific keys. The obvious weakness of this type of key is that if the unknown specimen lacks a particular morphological character necessary for keying, the keying process terminates at that point. Conversely, the advantage of this type of key is that the developer can be far more precise in forcing the user to follow specific steps to help guide the user through the process, thus reducing the risk of misinterpretations and misapplications of characters.   Random Access Keys Random access keys or polyclaves differ from dichotomous keys by allowing the user to select randomly, any character or set of characters (character states) in the order of convenience or ease of use. The obvious advantage of this system over traditional dichotomous keys is that any easily observable morphological structure or form can be applied first, i.e., plant habit or habitat, flower color, leaf armament, leaf position or type, fruit texture, etc., few of which are used as lead characters in traditional, dichotomous keys.   Like dichotomous keys, random access keys also have disadvantages, the most serious of which is the enormous quantity of time required by the key developer to score accurately all plant  species that share a particular character, and to establish the precision necessary to direct the user to interpret characters accurately every time they are used. For large floras, many months can be spent applying a single character, i.e., flower color or flowering time to all species. Moreover, since the degree of morphological variability associated with some of these characters can vary greatly, if used early in the key, they can cause failures; regardless of the number of redundancies built into the key.   With nearly a half-century history in key development, we believe that mixing certain aspects of both types, and then linking phytogeography and photography, offers the best results, with the highest degree of accuracy in identification.   Here is how our BONAP draft keying process works most effectively:   STEP 1 – Select your county or zip code by using the “Search by U.S. Zip Code, County or Location” located below the buckskin-colored “State-Level Query Map.” Alternatively, you can select your state or geographic area from the Query map.   STEP 2 – Scroll to the Family Identification Key. Proceeding from left to right, selecting character states that best match your plant. Open each character box found within the five columns. The various columns reflect characteristics for each major plant organ and are preceded by a column of general plant charcteristics. Character states shown within the pale blue color are deemed to be most effective in reducing species, most easily observed and understood by users.   NOTE – Do NOT guess. It is unnecessary to score all characters within the various character boxes. Score only those for which you feel certain.   Once you have completed scoring the family key, click the green-colored “Run Query” button below the key. You will notice that the three nomenclature columns (on the right side of the page) contain the names of the plants that remain. Remember: This is a family key, designed to key plant families globally, which I have modified to identify North American plant families only. Therefore, it may seem odd that some families still remain after certain characters have been selected.   Also remember, this is a family key only. Therefore, some of the genera and species remaining may or may not appear to reflect the characters selected. Many of these genera and species will be eliminated by selections made in the next step (Step 3: Biological Attributes Portion) of the keying process.   STEP 3 – Proceed by scrolling to the Biological Attributes Query box. For your convenience, we have arranged the attributes sequentially, by ease of use and significance. Click on every category and subcategory and select all of the characters that best reflect the condition of your unknown plant. Unlike the Family Key, it is important to score as many attributes as possible, but remember, don’tguess.   STEP 4 – Once you have scores all of the relevant characters in the Family Identification Key, and Biological Attributes Query and selected your geographic location, state or county, to view images of all remaining possible species, select the ‘Query Photo Gallery’ button to the bottom-right of Darwin’s picture.    IMPORTANT NOTE: Even though you may have scored a character in the Family Key, it is essential that you score it again in the Biological Attributes Query, since you are now keying species or small groups of species. Once you feel that you have entered all character selections, click the Run Query button. If numerous plants still remain, you can return to either the Family Key or Biological Attributes Query sections to determine if additional characters might be useful for further reduction. Once the keying process is completed, you can engage the Photo Gallery to match your plant with the available photographs. Remember that the keys are designed for flowering plants (save grass-like plants, i.e. Cyperaceae, Poaceae and Juncaceae). Keys for ferns and gymnosperms and grass-like plants are under development.   IMPORTANT NOTE: While keying, one trick to help reduce errors is to engage the “Run Query” button after each character selection for both the Family Key and Biological Attributes. The graying-out of characters will effectively reduce competing characters that are not applicable.   ***Although we had considered incorporating additional Boolean logic of “OR”, “NOT” and “AND” into these keys, such additions (e.g. “OR”) can often weaken the effectiveness of a key. Also, since the use of “NOT” is often misunderstood, unintended elimination of species occurs commonly.   Please remember the our keys are in DRAFT form. We would be grateful to learn of any errors.