Plant Identification Techniques: The Botanist’s Toolkit

Associating an unknown entity with a known one—or realizing that the unknown entity has no known counterpart—is the process of identification. To put it another way, identification is the determination that a perceived entity meets the requirements for being classified as a member of the same “class” as a known entity because it is sufficiently similar to the known entity. The entity itself could be a tangible thing or only an idea in the mind. Humans, other animals, and maybe all life at some level of organization engage in the basic action of identification. Strong selection pressure has surely played a role in the evolution of the ability to distinguish between, for example, edible and harmful, or friend and foe.

Determining the boundaries or characteristics of the known is crucial to identification because no two entities are precisely the same. For instance, determining whether a plant “belongs to” a specific taxon, such as a species, requires examining a live plant, a plant specimen, or a photograph of a plant. This identification is based on some kind of previous description of the taxa that are potentially involved as well as the unknown plant. It is crucial to assess each potential taxon’s diagnostic characterization (diagnosis), which is a list or appraisal of the characteristics that set it apart from all other taxa. If the unidentified entity’s traits fit inside

METHODS OF PLANT IDENTIFICATION

Almost every sense in our body can be used to identify plants. It is possible to recognize a plant by its flower’s scent, by the texture of its leaves or by the flavor of its fruit. In reality, when identifying or verifying the identity of an unfamiliar plant in the field, experts in a particular plant group frequently rely on smell, touch, and (sometimes) taste. (Normally, we wouldn’t use our sense of hearing to identify plants, although we can definitely learn to tell trees apart by the sound of the wind rustling their leaves.) However, sound may be the primary sense employed when recognizing some species, like birds. Nonetheless, eyesight serves as the primary method of plant identification for the vast majority of us and most of the time.

When light is reflected from a plant or plant portion, our brains can nearly instantly translate that reflection into what is known as a visual image. We are unaware of this visual pattern, at least for a split second. Identification is the process of linking an unfamiliar visual pattern to a recognized one that is either stored in our memory or inferred via the use of identification tools. Our brains absorb information in two main ways when identifying a plant (or any entity): holistically and analytically. When anything is perceived or prioritized holistically, it is processed mentally as a whole. The majority of skilled systematists who are knowledgeable about a certain group or floristic region identify plants holistically. They have the ability to quickly process the visual pattern of light reflected from objects such as leaves or flowers and almost immediately link that pattern to their recollection of a pattern that is comparable for that particular plant.

Moreover, the related pattern is usually—though not always—associated with a name. The processing that emphasizes an object’s component pieces is called analytical processing. Analytic identification entails breaking down or subdividing the whole object into parts, typically using specialized descriptive terminology. One could examine the arrangement, position, orientation, type, size, attachment, base, margin, apex, venation, texture, and surface aspects of a leaf, for instance.

When analyzing plants that require thorough dissection and inference, or when distinguishing between species requires examining fine or cryptic features, analytical processing may be more frequently utilized by someone with little prior knowledge of the plant group. In practical terms, the identification of a plant from among hundreds of thousands of candidates frequently necessitates a preliminary selection of those candidates. Regional floras are usually used to identify whether a plant is native or naturalized, while it is always possible that the plant in issue is new to the area and not represented in the flora. To be confident that the flora selected includes that of the unknown species, one should verify its geographic range. Identification of cultivated plants can be especially challenging. This is somewhat accurate because a sizable number of plants are cultivated, and the number grows yearly. Since a domesticated plant can originate from any area. There are several methods of identifying plants. These are described below.

TAXONOMIC KEYS

A taxonomy key is possibly the most helpful identification tool. A key is a means of identifying that involves making sequential choices from a list of options until just one remains. The majority of keys are practical; they identify a taxon in the most economical and efficient way possible. A bigger group may or may not be divided into smaller, naturally occurring (monophyletic) subgroups by the key. Dichotomous keys are the most prevalent kind, especially in floras and monographic treatments. This is made up of two consecutive statements that are referred to as leads; the two leads combined make up a couplet. A couplet’s leads may be numbered or indented.(See image bewlo). A well-written dichotomous key may have several types of evidence presented, with every character of the first lead matched, respectively, in the second lead (See image bewlo).

Since the majority of keys are artificial or practical, their sequential groupings do not purposefully follow natural groups; instead, their primary objective is to most quickly and easily identify a particular taxon, without regard for classification into other groups. On rare occasions, a key could be phylogenetically or naturally occurring, in which formal taxa, or even diagnostic or apomorphic traits, are employed to define “natural” groups. A key to the Asteraceae tribes is an example of a natural key. Natural keys involve more subtle and technical characteristics, making them less useful for practical identification. However, they can indicate the characteristics that distinguish different taxonomic families. When utilizing a dichotomous key, some safety measures need to be followed. The most crucial thing to do is read both leads through completely before deciding which one best suits the plant. It’s always a good idea to read both leads; even though the first one seems to fit, the second one might fit even better. Both leads of a couplet should be taken into consideration if, after reading them both, you are unsure which is accurate.

The two (or more) choices that were determined might then be compared to descriptions, examples, or comparisons of specimens. Another type of identification device is the polyclave key. A polyclave (or “multi-entry”) key is made up of a list of many character states, from which the user can choose any state that corresponds to the specimen (see table below). It is possible to identify the correct taxon (or closest match) or reduce the number of possible taxa by determining which of the several character states matches. Today’s polyclave keys are all operated by computer algorithms. Polyclave keys offer a significant benefit over dichotomous ones in that they allow for the utilization of a restricted subset of data to at least reduce the number of possible outcomes. For instance, if a dichotomous key solely includes floral features, its applicability can be restricted in the event that your plant specimen is devoid of flowers. However, in addition to floral properties, a polyclave key will include list traits of the fruits, seeds, roots, stems, and leaves.

SPECIMEN COMPARISON

Comparing the questioned plant to a living or preserved plant collection—typically a recognized herbarium specimen—is a third technique of identification. This is a great way to identify plants because a lot of their characteristics (such color and surface characteristics) are frequently not well described in textual descriptions or discernible from images or illustrations. As with the foregoing methods, comparison to an herbarium specimen is practically limited to verifying an identity after a subset of possibilities is narrowed down. In this sense, synoptic collections—which typically contain one specimen of each taxon for a certain region, such as a county—are quite helpful. When a taxon is restricted to a smaller group, such a family or genus, a fast search through the region’s synoptic collection can frequently help identify the unknown taxon. However, this approach has a caveat in that it relies on the accuracy of the herbarium specimens’ own identification. As a result, a written description should always be used to confirm a potential match.

IMAGE COMPARISON

A fourth method by which an unknown plant may be identified is by visually comparing it to photographs or illustrations of known taxa. These are usually obtained from books, although web page images have now become a very useful resource. A practical problem with this method is that photographs and illustrations are usually available only for a small subset of possible taxa. In addition, it may be cumbersome to locate the matching photograph or illustration, necessitating an examination of all those available. Comparing visually to a photograph can be a useful method for plant identification, especially when narrowing down the choices in advance. An important risk of this method is that two or more species may appear extremely similar in an image or drawing, with distinctions potentially lying in obscure morphological traits that are not readily evident. Therefore, any identification of the unknown plant based on visual appearance should be validated with a technical description of the plant.

EXPERT DETERMINATION

A fifth and final means of identification is simply to ask someone else, preferably an expert in the group in question. This method may be time-consuming, as it usually requires sending a specimen away for identification (as well as knowing who the experts of a given group are). However, expert identification is perhaps the best way to identify a specimen, as the expert will usually know the taxa of that group over a wide geographic range. If the expert is familiar with all recent literature on the group, his or her determination is often more accurate and current than any flora. Expert determination is often essential for certain groups in which species or infraspecific identification is very difficult.

PRACTICAL IDENTIFICATION

The identification of plant taxa is typically based on the expertise of the individual making the determination. The greater your knowledge, the simpler it becomes to identify a plant. For instance, many floras start with a key to plant families, which might be complex due to the need to include the diversity within the entire flora. Having prior knowledge of the broad characteristics of various families is beneficial as it allows you to go straight to the key genera within that family. If you have a general concept of the family group to which the taxon belongs, such as a suspected genus, it is advisable to consult the keys, pictures, descriptions, or specimens within that group initially. When unsure, it is advisable to begin from the outset to ensure the removal of similar yet inaccurate options. It is crucial to accurately identify a specimen. Once a decision is reached, it should be considered as provisional. Never presume you have arrived at “the correct answer” via any single method; it is crucial to verify your conclusion through all possible methods. Challenge yourself by playing the role of your own devil’s advocate and thoroughly evaluate your thoughts and actions. Authenticate each identification by comparing it to a documented description.

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