The following entries are arranged in alphabetical order by the scientific name of the major botanicals treated. (Some botanicals are treated only as secondary topics or contaminants, and can be located in the index.) Some explanatory notes on the content of the entries should be provided first.
The AHPA-selected Standardized Common Names and other frequently encountered common names are provided under the title of each entry. For the most part, only English common names are given. The exceptions are for non-Western botanicals whose vernacular common names are frequently used in herbal literature.
Just as related species are grouped into genera, related genera are grouped into families, which often share unique combinations of characters that enable their quick recognition. Getting to know these families is one of the keys to easy plant identification. In modern taxonomic practice, a family is named for one of the included genera, and has the ending -aceae. For example, the daisy family (Asteraceae) is named for Aster. Older family names did not always follow this pattern, and eight of the largest and most economically important plant families have accepted alternate names that have been conserved because they are so common in the literature. For example, Asteraceae may also be called Compositae. These names are included in parentheses. Sometimes there has been a difference or change of taxonomic opinion about what genera should be included in a particular family; all of the common opinions are given as alternatives here. Family names are not italicized in American practice, although they often are in Europe.
The approximate size and distribution of the genus to which each plant belongs is given. On occasion, the infrageneric classification is mentioned as well. A large and complex genus may be divided into subgenera, sections, and/or series. If multiple levels of division are used, a subgenus outranks a section, so that one subgenus might contain multiple sections, and a section outranks a series. If the plant is part of a taxonomically difficult species complex, so that species boundaries are not certain, or if hybridization among species is frequent, these facts are noted. Many variable species have been divided into subspecies or varieties, which are often of little practical use; these are mentioned only when they reflect significant taxonomic distinctions. Important synonyms that might be encountered in literature are listed. Some plants have dozens of synonyms that are never used at all; these are omitted. Where more than one species may be used interchangeably, the situation is discussed.
A brief botanical description of the whole plant is provided for purposes of general information and to assist those who wish to confirm the identity of aboveground parts (or pressed voucher specimens made from those parts) or, perhaps, living material as it is harvested. Jargon has been minimized, but the glossary in the back defines unavoidable terms. Measurements or variation in number of parts are given in metric as ranges, e.g., “5–8 cm long” or “stamens 4–5.” Likewise, “2–3-pinnately compound” describes a leaf that may have either two or three orders of division. A common practice in taxonomic literature is to set the extremes of a range aside in parentheses, e.g., “(3–)5–8(–15) cm long” means that the plant part is usually 5–8 cm long, but rarely may be as short as 3 cm or as long as 15 cm. Figures for stem height, leaf length, etc. in taxonomic literature refer only to mature plant parts: in many plants, younger leaves are present in a complete size range, down to very tiny, so the presence of some small leaves is not suspicious, whereas that of very large leaves would be. Descriptions are derived from published scientific literature (including floras, revisions, and monographs) and herbarium specimens, but are not intended to be exhaustive. It should be remembered that probably no description ever published has completely encompassed all the possible variation in a species, because “the plants haven’t read the book!”
Parts in commerce
The listed parts are those that are most commonly used and that seemed most amenable to treatment in this text. These choices do not imply that other parts may not also be used, even frequently. For example, grape seed is described but whole grapes are omitted, not because they are rarely used, but because everyone knows exactly what they look like.
The bulleted lists provided focus on key features of the parts in question, expanding upon the botanical description and using the simplest possible language. The intention is to separate the complex description of a plant into a list of simpler features that can be checked one by one. Both positive characters (those which should be present) and negative characters (those which should not be present in correctly identified material) may be noted. Sensory or organoleptic characters (e.g., taste and odor) are also listed, as these are often very important, although people vary in their ability to discern different tastes and smells. Other such characters include texture and (for roots and barks) the fracture, or how hard a dried piece is and how it breaks, which was an important character in traditional pharmacognostic descriptions. The language used in that literature to describe fracturing is diverse and perhaps rather subjective, but there is a palpable and visible difference between a hard, short fracture and a very fibrous fracture or a brittle fracture. Tasting, smelling, feeling and breaking as many plant samples as possible will help to develop the ability to perceive subtle differences among botanicals. Although lab tests requiring expensive or restricted reagents have not been discussed in this manual, there are a few very simple chemical tests which may enhance one’s confidence in the identity of certain botanicals. These have been mentioned briefly under the relevant entries.
Certain species have been reported in pharmacognostic literature to be inappropriately present in material that was sold as some other species. This can be the result of accidental substitution (in which the wrong plant is mistakenly identified as the correct one, or believed to be interchangeable with it), accidental contamination (in which some admixture of the wrong plant is harvested along with the correct one), or fraud (in which a cheaper plant is deliberately substituted for or mixed with the correct species). Adulteration can also involve the use of improper plant parts of the correct species, for example, the inclusion of many large stems in a product supposed to be made from leaves only. In common speech, “adulteration” implies the deliberate manufacture of low-quality products. In the botanical industry, “adulteration” is used generically to refer to any inclusion of incorrect plant species or plant parts in excessive quantity, whether deliberately or by accident. It is used here in that sense, so no imputation of motives is implied or should be assumed: most reported adulteration is unintentional. Related species of commercial importance may also be discussed in or around this section even if they are not known to be adulterants of the primary species. Means of distinguishing wild-collected plants from relatives found in similar habitats may be mentioned; again, this does not necessarily indicate that adulteration with those relatives has been reported to be a problem in practice, only that it could be possible.
References used in compiling each entry are cited at the end of that entry. These frequently contain further information, omitted here, that might be valuable to those interested in a specific plant. Several major pharmacognostic or botanical references that were used frequently, together with some general references useful for such subjects as nomenclature or anatomy, are additionally listed in the reference section at the back of the manual.
To aid the reader in interpreting descriptions, botanical illustrations are provided for many plants. Multipart figures occasionally include illustrations of a particularly important adulterant or relative as well as the primary species, so check the caption!
Please note that in some botanical entries the order of these sections may be changed in order to allow the identification information to remain in close proximity to the corresponding figure.