This manual is written with the assumption that most readers have either taken a botany course or had practical experience working with plants or botanical materials, so that they have some familiarity with the basic structure of a plant. Space limitations require that a review of plant morphology be kept to the barest minimum. If a more detailed review is needed, any textbook of botany or plant biology will suffice (Raven, Evert & Eichhorn’s Biology of Plants is highly recommended). Technical vocabulary is kept to a minimum in this text; that which cannot be avoided is defined in the glossary. A more complete reference is Harris & Harris’ Plant Identification Terminology. Within those limitations, let us take a few paragraphs to review the structure of typical flowering plants.

Flowering plants, like other “advanced” vascular plants, have complex forms that are constructed from just a few basic types of plant organ. An average plant has a root or roots, a stem, leaves, and flowers, which produce fruits and seeds. There are of course variations; for example, plants such as dandelions have all leaves borne at ground level, with no stem, while others, such as many cacti, have no leaves. In some plants, the stems become thick and woody trunks, branches or twigs.

These organs are constructed in turn from a limited number of basic tissue types. Many of the soft tissues of a plant, such as the photosynthetic inner parts of a leaf, the ground tissue of a stem, or the fleshy cortex of a root, are made of unspecialized cells called parenchyma. There are also specialized tissues that transport nutrients, including phloem, which transports sugars from the leaves to the roots, and xylem, which transports water from the roots to the leaves. Each of these is a complex tissue that contains different types of cells adapted for specific purposes, including rays of unspecialized parenchyma. Xylem often includes hollow pipe-like cells of large diameter, which have a distinctive appearance, whereas phloem, except at high magnification, does not appear much different from parenchyma. These vascular tissues are found in small strands or bundles in herbaceous stems, in roots, and in the veins of leaves, petals, etc. In woody stems and roots, secondary xylem and phloem are produced in larger quantities; the secondary xylem and associated tissues make up the wood. There are also many different specialized cell types that may occur within parenchymatous tissues. These may play a support function, like collenchyma (the strings in celery) and sclerenchyma (thick-walled elongated fibers, or rounded stone cells such as the grit in pears), or they may have the function of secreting or storing special compounds, such as resins, oils or mineral crystals. The outer surface of a plant is covered with a protective epidermis or, in woody stems and roots, with a cork layer. The epidermis may produce hairs (trichomes) or glands.

Roots may be taproots, which are thick and single or few in number (like the carrot), or they may be fibrous roots, which are thin and numerous (like grasses). In some plants, the taproots have well-developed secondary wood, and the outer surface has a thickened bark. The anatomy of a root is best seen in cross-section. A typical small root, such as a fibrous root or a very young taproot, contains, moving from the outside toward the center, a single-layered epidermis, a ring of parenchyma called the cortex, a single-layered hypodermis, and a central vascular cylinder, which contains a small amount of outer parenchyma (pericycle), small bundles of phloem, and a variously shaped central xylem. Occasionally (especially in monocots) vascular tissues are found in a ring around a central area of parenchyma (pith) without vascular tissue, but usually roots have no pith. Such very small roots are seldom harvested (except incidentally when attached to stems, rhizomes, etc.) and provide few identifying characters.

In many larger taproots, secondary xylem develops, making a conspicuous central cylinder of wood that may occupy most of the root’s volume. (This “wood” need not be woody in the same sense as an oak tree! For example, the paler area in the middle of a carrot is secondary xylem, and therefore technically wood.) Secondary xylem is formed by the vascular cambium, a single ring of cells that produce layers of xylem toward the inside (thus moving outward as the thickness of the wood increases) and secondary phloem toward the outside. The xylem and phloem may be in continuous rings or in groups; a common morphology is for strands or wedges of wood and phloem to be separated by parenchyma rays extending radially from the center of the root toward the surface, giving the root a spoked appearance in cross-section. The expansion of the wood often ruptures the original cortex and epidermis, which dies and peels off; a corky bark develops as the outermost layer. Between the cork and the secondary phloem, there may be a ring of parenchyma that resembles a cortex, and may be referred to as a secondary cortex, but that actually developed from the pericycle. “Bark” (as explained below) refers technically to everything from cork through secondary phloem.

The vascular tissue of most herbaceous dicot stems is not at the center, but spaced in a ring of vascular bundles around a central pith; vascular bundles of monocots are scattered randomly through the parenchyma of the stem. When secondary growth has begun in a dicot stem, from a single-layered cambium ring as in the root, there is an outer ring of cortical tissue, a ring of secondary phloem, a cambial layer, and a ring of secondary xylem that surrounds a pith. The presence of this pith usually differentiates a stem from a root. Stem anatomy is not usually very useful for plant identification and is seldom important, as there are few plants for which stems alone are used. An exception is when rhizomes are used. Some plants have roots arising from a short rootstock or rhizome that is actually not the uppermost part of the root but the lowest part of the stem. The rootstock’s anatomy is often similar to that of the root, except that there is a central pith in which there is no wood. Other plants have horizontal underground stems (rhizomes), which may be very long and the means by which the plant spreads. These are often called stolons if they are above ground level. In some plants (e.g. black cohosh) the major underground structure is a rhizome and the roots are small.

Bark is often harvested from older woody stems. Bark is actually a very complicated tissue, including several specialized cell layers that cannot be seen without the use of the light microscope. Bark includes all the tissues between the outermost layer and the secondary vascular cambium; in other words, everything outside the secondary xylem (wood). The outer portion includes multiple layers of protective cork, which is dead at maturity. The epidermis is destroyed when the cork is produced, and in older stems the production of lower layers of cork inside the secondary phloem causes the original cortex to rupture and peel off as part of the outer layers of bark. Since the cork is airtight, the outer bark has small pores (lenticels) that permit gas exchange; these are sometimes conspicuous and have a characteristic shape. The inner bark includes the cork-producing cells, any remaining cortical parenchyma, and a layer or layers of secondary phloem, which may contain visible parenchyma rays. When bark is harvested, it is the living inner bark rather than the dead outer bark that is valuable, so bark is removed down to the wood. In some botanicals, the outer bark is traditionally stripped off at the time of harvest.

Fortunately, the characters that describe leaves, flowers, etc. depend more on visible morphology than on internal anatomy! A typical leaf has a blade (the flattened photosynthetic portion) and a petiole (the leafstalk). Some also have a pair of small leaflike structures (stipules) at the point where the petiole attaches to the stem. Leaves are categorized by their arrangement on the stem (alternate, opposite, or whorled), whether they have a petiole or are sessile (stalkless), and whether they are simple (undivided) or compound (including more than one leaflet). If compound, they may be palmately or pinnately compound, and the leaflets may be be sessile or stalked. A full description of a leaf includes the size and shape of the blade, the shape of the base, apex and margins, the pubescence and appearance of both surfaces, and the pattern of venation. An enormous vocabulary can be used to describe these characters; some of the most basic terms are defined in the glossary. Certain characteristics are usually treated as “default” values, which are assumed to be the case unless otherwise noted. For example, leaves are presumed to be simple, to have a petiole, to have entire (untoothed) margins, and to be glabrous (hairless), unless they are specified to be compound, sessile, toothed, hairy, etc.

Flowers are either borne on individual stalks (pedicels) or sessile, and may be borne singly or in clusters called inflorescences. The position, size, and shape of the inflorescence may be of taxonomic use. They may be terminal (at the ends of stems) or lateral (borne on short side branches or individually in leaf axils). The stalk subtending the whole inflorescence is called the peduncle; within the inflorescence, it is technically called the rachis. Flowers are sometimes subtended by leaves or by small, often leaflike structures called bracts. Types of inflorescence are distinguished based on which flowers develop first, whether the rachis branches and how, and whether the flowers are stalked or sessile. (The glossary defines several common types.) There are also specialized or unusual inflorescences, such as the head or capitulum of the daisy family and the compound umbel of the carrot family, that are found only in certain plant groups.

A common garden flower typically includes four whorls of parts arising from a common receptacle: the usually greenish sepals (collectively called the calyx), the usually colorful petals (collectively called the corolla), the male stamens (collectively called the androecium), and the female carpels (collectively called the gynoecium). Sepals and petals together are called the perianth. In some flowers, the sepals and petals are identical, or reduced to only one whorl; when the perianth parts cannot be divided into two groups, they are referred to as tepals. A typical stamen consists of an anther (which produces the pollen) and a filament (the stalk on which the anther is raised). A typical carpel includes an ovary (containing one or more ovules), a stigma (where the pollen lands), and a style (the stalk on which the stigma is raised above the ovary). Flowers may be bisexual (having both stamens and carpels) or unisexual, then bearing male and female flowers separately on the same plant (monoecious) or on different individuals (dioecious).

Individual sepals, petals and filaments may be free (not attached to one another), or they may be more or less fused to one another. They may also be partly fused to parts from other whorls; for example, in many flowers the bases of the filaments are fused to the corolla, giving the appearance that the stamens grow from the corolla. It is very common for all the carpels in a flower to be fused, forming a single compound ovary; the styles and stigmas may remain separate or may also be fused. A compound gynoecium is often called a pistil (and a single solitary carpel is sometimes called a simple pistil), but if there are several free carpels they are not called pistils. A less common form of fusion is for the basal parts of the sepals, petals, and filaments all to be fused into a long or short tube (hypanthium). If the hypanthium is in turn fused to the sides of the pistil, so that the free parts of the sepals, petals and filaments appear to arise at the top of the ovary and the ovary appears to be embedded within the receptacle, the ovary is called inferior (otherwise, it is superior). Descriptions of flowers may include the number, fusion, symmetry, shape, size, color, and pubescence of the parts in each whorl. There is, again, a great deal of terminology to describe their shape; some common shapes are defined in the glossary. As with leaves, certain character states are commonly treated as the norm, and presumed to be present unless specified otherwise. The “normal” or default flower is bisexual and radially symmetrical, without fusion of perianth parts or filaments, and with a superior ovary.

A fruit is a mature ovary, sometimes with attached tissues such as hypanthial tissue, and seeds are mature fertilized ovules. Fruits may be dry or fleshy, dehiscent (splitting open at maturity) or indehiscent, and one-seeded to many-seeded. If formed from a single carpel, a fruit will have only one locule (the space inside the ovary that holds the seeds). A compound ovary may have a single large locule, or may have as many locules as carpels, divided by septa, as in the tomato (although it is rarely so easy to observe). Common fruit types are defined in the glossary.

The specialized descriptive vocabulary of size, shape, texture, and so forth can seem overwhelming to the student, and it has been minimized as much as possible in this volume. The botanical descriptions provided are simplified from descriptions in taxonomic literature, and the authors of such treatments would probably feel that sloppy language was being used. Still, the lay reader may feel that the terminology is excessive and even unnecessary: why, for example, would one use a special Latin word like “orbicular” to describe the shape of a leaf when the familiar word “round” is available? The primary reason is that common English adjectives may have unclear meanings when applied to specialized structures. A flat leaf with a circular shape could be described as round, but so could a fleshy or needle-like cylindrical leaf that is round in cross-section. Having two different terms for these conditions (orbicular vs. terete) makes it immediately clear, once the vocabulary becomes familiar, which state is meant.

Many important taxonomic characters are difficult or impossible to observe with the naked eye. For example, you may wish to count the number of tiny teeth at the apex of a ray floret of a composite, or determine whether a leaf has minute hairs in the axils of the veins. Anatomical structure of parts such as roots and bark is particularly hard to see. A good hand lens, used in good light, will suffice for many purposes. However, for those who will be looking at a great deal of material, a dissecting microscope is very useful. This should not be confused with a light microscope, which has a built-in light in the base, a raised stage for slides, and several objective lenses for increased magnification. A dissecting microscope has a much lower range of magnification and a low stage on which a fairly large object can be placed, with room under the head of the microscope for hands holding tweezers, etc. A separate lamp illuminates the object. Dissecting microscopes are much more comfortable to use than hand lenses, with binocular eyepieces and a greater maximum magnification that provides better resolution of very small features. Forceps and perhaps dissecting needles should also be obtained, as they allow convenient manipulation of small plant parts.

One must expect harvested plant material, even of a whole herb, to look very different from live plants of the same species. Unless plants are small, people do not normally collect whole plants. Larger plants would typically be cut or broken into pieces; only the tops may be collected, or lower leaves may be stripped from thick stems, which are then discarded. Since dried material is often brittle, more breakage can occur during initial processing. Some characters, such as the height of a large plant, usually cannot be observed, and others may be observed only imperfectly. For example, if a plant has large, petiolate lower leaves but smaller, sessile upper leaves, broken pieces with each type of leaf base may be found, but not attached to a stem in a neat sequence.

Dried material also may change appearance greatly by shriveling, which can make parts hard to measure, and colors may change to some extent (although if colors are too faded, it is often an indication of poor quality due to improper processing). Dried flowers may lose parts such as petals, which may be found loose. Most dried leaves, flowers, and fleshy fruits are more easily examined if they are rehydrated. Various wetting solutions may be used to rehydrate herbarium material. The simplest is to use hot water with a very tiny spot of dish soap in a watch glass or similar container. Solid or hard fruits do not rehydrate as quickly, and the use of boiling water can be helpful. With a few chemicals, a more efficient wetting solution can be made. Dr. Lynn Clark’s Modified Pohl’s Solution (based on a recipe by the late Dr. Richard Pohl) uses 750 ml distilled water, 250 ml 1-propanol, and 2 ml Ivory liquid soap to make one liter of solution; it can be kept in dropper bottles. Once material has softened, it can be spread out with forceps so that its original shape and size can be seen.

Sometimes the initial processing of an herb leaves it broken into rather small pieces, which is less than ideal, but informative parts may be found with patience and care. Small flowers often remain intact in broken material, although inflorescences usually do not. Information regarding the likely shapes of the leaf base, apex, or margins, the venation pattern and the presence of surface pubescence or glands may be obtained from broken leaves by sorting through the pieces to find those that include suitable portions of the leaf. If leaves are broken, it may or may not be possible to estimate their size accurately by examining the larger pieces. Leaf size is more likely to be an important character in plants that have uniformly small leaves, rather than those that have leaves potentially ranging in size from small to enormous. Small leaves, even when broken, often include enough of the leaf in a single piece to allow some estimate of the size to be made. (The exception is if material has been comminuted, or broken into tiny fragments in which few taxonomic characters remain visible. A few plants are traditionally treated like this during their initial processing, but botanicals of Western origin ought to have their identity certified before they are processed to that degree.) Sliced roots and rhizomes should be sorted through to find pieces that give the best view of the internal structure, which means those that are cut most nearly straight across rather than at an angle.

Fortunately, quality control of botanicals does not usually involve actual identification, but confirmation of identity. One doesn’t start with an unlabeled unknown and have to determine from scratch which of the 300,000 or so species of higher plants it is, which can be an exhausting task even with the best of material. Rather, one starts with a plant that has already been named by someone else, and must determine only whether that initial identification seems to be correct. If not, one simply rejects the material, without any need to figure out what it actually is. Knowing what the plant is supposed to be makes the use of botanical literature (including this manual) much simpler. One only has to look up descriptions of the plant named and ask: are these consistent with the material at hand, or not? The material can also be compared to illustrations, or to previously obtained reference plant materials of known identity. Such comparisons are not always straightforward: some plant species have highly variable leaf shape or pubescence, for example, and material that does not look much like a given illustration or reference sample might in fact be the same species. Written descriptions can make it clear when features of a species are variable, thus avoiding “false negatives” in which correctly identified material is wrongly rejected.

For those who are buying a large amount of a single botanical, a sampling scheme is necessary to ensure that a sufficient amount of the material has been checked for identity. Otherwise, one might by happenstance check the only portion of the material that did not contain excessive levels of some adulterant! A useful approach is outlined by the World Health Organization’s manual, Quality Control Methods for Medicinal Plant Materials (1998). In WHO’s recommended system, at least 10% of the containers in a batch should be sampled, rounded up, with a minimum of five containers (or all of the containers if the batch includes four or fewer). For each container, equal samples should be taken from the upper, middle and lower portions of the material, mixed, then repeatedly mixed, quartered, and divided in half by returning diagonally opposite portions to the container, until a suitable amount remains. These samples would also be used for any laboratory tests performed, such as ash content and screening for chemical markers, and for preservation of voucher specimens for each batch in case doubts about its identity should arise later.

Comparing a written description to illustrations or to reference specimens often enhances one’s mental picture of a plant. Previously obtained reference material of known identity is particularly useful because it can convey information on color, texture, and the like in more detail than any description or illustration. To avoid “false negative” results in which the identity of material is wrongly called into question, one must remember that an illustration or a piece of reference material represents a single individual, and thus can display only a portion of the variation that is present within a species. For example, if the flower portrayed is hairless and the flowers of the material to be identified are hairy, they may belong to the same species, yet appear substantially different at first glance. In case of apparent discrepancy between the material examined and the illustration or reference material, one must therefore consult a written description to determine whether the suspect character is indeed found in that species.

There are two types of names that are applied to every useful plant: common names and scientific names. Common names are those that are used in ordinary conversation, and are in a vernacular language (e.g., wheat, apple, dandelion). These are convenient enough for most purposes, but can create confusion. Many plants have multiple common names, e.g., Chenopodium album can be called goosefoot, fat-hen, lamb’s quarters, or pigweed in different parts of North America. Moreover, the same common name may be used for different plants in different places: pigweed sometimes refers to species of Amaranthus, another edible weed. To minimize this problem, American commercial products are required to use “standardized common names.” The American Herbal Product Association’s book Herbs of Commerce, 2^nd ed. (McGuffin et al., 2000) provides an extensive list of marketed species and specifies for each the preferred common name (which in some cases is the scientific name or a portion of it). However, many of their choices are not exclusively used in ordinary English. For example, although the name “Siberian ginseng” for Eleutherococcus senticosus has been specifically outlawed in commercial speech, it is still the common name most used by laymen. Then there is the question of scientific or commercial communication with people who speak different languages. And, of course, there are many foreign plants that have no common names in English. A scientific or Latin name is intended to provide a name for a plant that is “always correct” and can be used to communicate about that species among botanists worldwide, no matter what language they speak.

A full scientific name has three parts, in the form Genus epithet Auth.: the genus in which the plant is placed, the specific epithet, and an abbreviation of the name of the “authority” who first published that species in scientific literature. Binomial or Linnaean nomenclature requires that each species belong to a genus (plural: genera), a group of closely related plants, such as Echinacea or Panax. The species within each genus are denoted by specific epithets, which often refer to the plant’s appearance, origins or uses, e.g., angustifolia, narrow-leaved; africana, from Africa; officinale, of the shops (often used for medicinal plants). The species name includes both the genus and specific epithet, such as Echinacea angustifolia, and is printed in italics because it is in Latin or Latinized. The ending of the specific epithet is in the form of a Latin adjective, and changes depending upon the Latin gender of the genus. (In an homage to classical tradition, the name of a tree is traditionally treated as feminine no matter what its apparent gender.) After the first mention in a text, the genus is often abbreviated (except at the beginning of a sentence, where it should be spelled out), and the authority is always omitted, e.g., E. angustifolia. The reason for including the authority at first mention is that sometimes the same name has been used by two authors to refer to two different species, and providing the authority leaves no doubt which one is meant. The names of older authorities who published thousands of names are sometimes highly abbreviated, e.g. “L.” for Linnaeus. Sometimes the authority is of the form “Smith ex Jones,” which indicates that Jones actually published the name, but gave Smith credit as the authority responsible for the new species.

Most hybrid plants are not given formal names, but are described by their parentage, e.g. “Salix alba L. ×S. nigra Marsh.” If a particular hybrid is common and morphologically consistent, especially if it is reproductively isolated from its parents, it may be given a species name with an × before the specific epithet to indicate that it originated as a cross between two other species. This symbol may be added after a species has been described if it is later determined to be of hybrid origin, e.g., Mentha ×piperita L.

In the early days of botany, it was common for multiple names to be published for a single species, especially one that is found in many places or that is variable enough to be mistaken for a group of several species. These excess names are called synonyms. To reduce confusion, there should be only one correct name for a species under a given taxonomic treatment. The International Code of Botanical Nomenclature provides rules to determine what that correct name is. These rules are too complicated to recount in detail, but the principle of priority usually applies. That is, the oldest name that was “validly and legitimately” published for a species provides the specific epithet that should be used if possible. Certain errors in the publication of a name can make it invalid or illegitimate, meaning that it should not be used no matter what its age. (For example, if you publish a new name that had already been used by someone else, your name will be illegitimate.) If the strict application of these rules would lead to great nomenclatural confusion, there are procedures by which younger names can be conserved or older names rejected at the meetings of the International Botanical Congress, which are held every six years.

A particular issue to note is that the determination of the “correct name” only applies to a specified taxonomic treatment, and that under different treatments, a different name may be correct. Outside the botanical community, people often assume that species and even genera are groups that have a definite, objective biological meaning. This, perhaps, is because the mammals with which they are most familiar are easily distinguished and genetically separated from related species. In variable or freely hybridizing groups of plants, it is not always clear how many species should be recognized. The boundaries of species described in the literature are often someone’s taxonomic opinion rather than a hard fact, and other authors may choose to recognize more or fewer species in a group. The term “genus” has no real biological meaning at all. It is simply a group of closely related species that are recognized as such by being given the same name, often because they are similar enough to be recognized by their shared features. In modern taxonomic practice, it is desirable for genera to be natural groups, which comprise all of the descendants of some common ancestor, but the size of these groups is arbitrary. Where one taxonomist chooses to recognize one large genus, another might break that genus into half a dozen smaller genera. The same applies to the grouping of genera into families.

As for nomenclature, when a species is transferred from one genus to another, a new species name must be created for it. This name ordinarily uses the original specific epithet, with the original authority’s name or abbreviation in parentheses before that of the new authority. For example, black cohosh was described by Linnaeus as Actaea racemosa L.; later taxonomists chose to split Actaea into two genera, and the name Cimicifuga racemosa (L.) Nutt. was published by Nuttall for the same species. Each of these names is a synonym for the other, and A. racemosa is also the “basionym” of C. racemosa, or the original name from which its epithet is derived. Depending upon whether you recognize two genera or just one (which more accurately reflects relationships, according to the latest studies), the use of either name could be correct. Neither name becomes invalid or illegitimate. Occasionally the specific epithet cannot be transferred in that way because another species in the second genus has already been given that epithet. In this case, the epithet of a more recent synonym is used, or if necessary a new epithet is published for the species.

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.

Common names

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.

Family

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.

Taxonomy

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.

Description

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.

Identification

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.

Adulterants

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

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.

Figures

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.