Grass Names & Nomenclature

ANYWHERE IN THE WORLD, most grasses have at least two names: a common, or vernacular name, and a botanical name. Vernacular names are common names expressed in local language. For example, susuki is the Japanese vernacular name for the grass most English-speaking people commonly call miscanthus. Uncontrolled by governing bodies, common and vernacular names of grasses are constantly in flux, evolving with human culture, and for this reason they are both appealing and confusing. Often, they are quite local or regional in nature. A particular common name may have a very precise meaning locally but be ambiguous in larger context. The level of precision of vernacular names varies considerably. In Japanese vernacular, the name susuki is directly equivalent to the botanical name Miscanthus sinensis and ogi is equivalent to M. sacchariflorus. Japanese vernacular is so specific and precise that hachijo susuki is commonly used to distinguish the botanical variety M. sinensis var. condensatus. Although English-language vernacular names for these plants do exist, their use is neither common nor consistent, and English speakers are likely to refer to all three as miscanthus, or to rely on the universal precision of the botanical names, which is precisely why they exist.

Botanical Names

The system of botanical names has evolved for the purpose of providing a precise, standard method of communication about plants that is independent of language and regional culture. Botanical names refer to living things in the plant kingdom and are a subset of scientific names, which include the zoological names of animals.

Botanical names are Latinized names deliberately removed from the flux of any modern, living language. Though they are sometimes referred to as Latin names, this is imprecise since they are often derived from other languages such as Greek. Botanical nomenclature as we know it dates to 1 May 1753, when Swedish naturalist Carolus Linnaeus (who Latinized his given name, Carl von Linne) published a system of two-part names in his Species Planta-rum. The Linnaean system is in universal use by the scientific community, so a basic familiarity with it is usually necessary when discussing the great diversity of grasses.

The botanical names of plants are governed by the International Code of Botanical Nomenclature (ICBN), often referred to as the Code when the context is clear. The Code is constructed and periodically updated at the International Botanical Congress (IBC), a meeting comprised of botanists from all over the world.

The Code regulates various nomenclatural terms used to organize the plant kingdom into progressively narrower categories. The principal terms, in descending rank, are division, class, order, family, genus (plural: genera), and species (plural: species). A group of plants at any rank is called a taxon (plural: taxa). The grass family, Poaceae, is a taxon, as is the species Panicum virgatum. Taxonomy is the study of the classification of taxa. When inserted in text, botanical names of taxa are usually set off by a typographic device such as italic font or underlining.

A family is a group of genera whose members resemble one another in several respects. A genus is made up of closely related and similar plant species. The generic name is always capitalized, as in Carex. A species is an assemblage of plants that are similar in several characteristics. Cross-fertilization between plants of the same species produces seedlings that retain the distinguishing characteristics of the species. When referring to a single, unknown or unspecified species in a genus, it is correct to use the abbreviation sp. following the genus name, as in Carex sp. The abbreviation is not italicized. When multiple species of the same genus are referred to, the abbreviation spp. is used, as in Carex spp.

The Code dictates that each plant species must have a binomial (two-word) name consisting of the genus followed by the specific epithet (species designation), which is not normally capitalized. These two parts together make up the species name of a plant. In the case of Carex laxiculmis, Carex is the genus, laxicul-mis is the specific epithet, and Carex laxiculmis is the full name of the species.

When referring to multiple species of a single genus, it is acceptable to spell out the genus name of the first species and use only the first letter of the genus, followed by a period and the specific epithet, for subsequent species. For example, it is correct to say that cultivated miscanthus species include Miscanthus sinensis, M. oligostachyus, and M. sacchariflorus.

Hybrids between different species occur infrequently in regional ecosystems but are commonly produced through horticultural techniques. There are relatively few hybrids among ornamental grasses, but one widely known is Calamagrostis xacutiflora, a cross between C. epigejos and C. arundinacea. The multiplication symbol (x) is used to indicate the hybrid nature of a plant. Current rules of nomenclature dictate that the multiplication sign directly precede the first letter of the epithet.

Not to be confused with cultivated variety (see “Names of Cultivated Plants”), a botanical variety (abbreviated var.) is a nomenclatural rank below species. A variety differs from individual plants of the same species in one or a very few characteristics. For example, the flowers may be different in color or the leaves different in shape. Varietal names are never capitalized and are always italicized or underlined, as in the example Carex morrowii var. temnolepis.

The Code allows the formation of intermediate nomenclatural ranks by adding the prefix sub- to various taxa. Examples include subfamily, subgenus, and subspecies (abbreviated subsp. or, alternately, ssp.). An example of a grass with defined subspecies is Molinia caerulea. The typical subspecies is M. caeru-lea subsp. caerulea. Note that the name of this first subspecies is a repeat of the specific epithet. This is always the case, according to nomenclatural code. The second subspecies is M. caerulea subsp. arundinacea. If no subspecies name is given, it is understood that the name refers to the typical (first) subspecies. For example, M. caerulea is understood to mean M. caerulea subsp. caerulea.

Author Citations and Name Changes

The Code requires botanists to adhere to a number of precise requirements when authoring names of plants. When a plant is named for the first time, a specimen must be collected, pressed, dried, and preserved in an herbarium along with a proper description of the plant. The new plant name must be properly published along with the description, a reference to the location of the specimen, and the name of the author. In this way, the author’s name provides a direct link back to the plant, should confusion arise. This system ofauthorship is applicable to the various nomenclatural ranks including family, genus, and specific epithet.

All valid botanical names of plants have authors, and in scientific publications and professional references the author’s name, typically in standard abbreviation, is cited following the botanical name. For example, Carex L. is Lin-naeus’s name for the genus of sedges. The policy of Timber Press is to spell author names in full, for example: Carex Linnaeus. Though author citations are often unnecessary or impractical in popular texts and magazines, they can be of critical importance when communicating unambiguously about a complex group of plants such as the grasses.

The Code is founded on the principle of priority, meaning that the earliest validly published name has precedence. Authors are obliged to determine that the plant they have found has not already been named, a task which is easier today than it was in Linnaeus’s time. Occasionally and inadvertently, multiple names have been assigned to the same plant by different authors. When such errors are discovered, the rule of priority requires that the earliest val-idly published name be preserved as the correct one, and that the later names be consigned to synonymy. For example, the name Andropogon elliottii Chapman was found to be a later published name for A. gyrans Ashe, which is now given priority. Unfortunately, a botanical name may be in wide use for many years before it is found to be a later synonym.

Growing 6 feet (2 m) tall in late August in southern Germany, Molinia caerulea subsp. arundinacea 'Windspiel' is a cultivated variety of purple moor grass representing the taller of two subspecies.

Growing 6 feet (2 m) tall in late August in southern Germany, Molinia caerulea subsp. arundinacea ‘Windspiel’ is a cultivated variety of purple moor grass representing the taller of two subspecies.

Confusion also arises when the same name is, in error, applied to different plants by different authors. For example, the name Carex stricta was assigned by the botanist Jean Baptiste Lamarck to the North American native tussock sedge. Another botanist, Samuel Goodenough, later published the name C. stricta to describe a European sedge species. In this case, the authors’ names are necessary to confirm the identity of the species in question: C. stricta Lamarck is a different plant than C. stricta Goodenough. Nomenclatural priority preserves C. stricta Lamarck for the American species. Carex stricta Goodenough was determined to be a synonym of C. elata Allioni, which now has precedence. The author citation of C. stricta Goodenough, non Lamarck, makes clear that the plant in question is Goodenough’s European species, not Lamarck’s North American species. Without the author citation, C. stricta is ambiguous.

Name changes can also result from re-classification. Modern systems of plant classification aim to express the genetic relationships and evolutionary pathways of plants. In the past, information used to classify plants was often dependent on relatively unsophisticated tools and superficial observations. Modern technology now makes it possible to determine chromosome counts and minute differences in the chemical makeup of plants, and this information often reveals new or different plant relationships. This results in reclassification, which often results in name changes. For example, new data or newly interpreted data may reveal that a species formerly included in one genus really belongs in another. Botanist Harris O. Yates determined that the grass known as Uniola latifolia Michaux was sufficiently distinct to be reclas-sified in the genus Chasmanthium. The rules of nomenclature require that the specific epithet (latifolium) be re-used as part of the new combination C. latifo-lium (Michaux) Yates. Note that the original author’s name is retained in parentheses followed by the transferring author.

Changes in long-established names are usually inconvenient but necessary steps in the maintenance of a rational system. Because obsolete names survive in printed literature, it often takes quite a while before name changes are fully communicated and adopted. This is becoming less problematic with the advent of online taxonomic databases.

The Code does not determine how data concerning the classification of plants must be interpreted, it merely sets forth rules and procedures for theconstruction of the names themselves. For this reason, there is sometimes no absolute answer to the question “What is the correct name of this grass?” Since living organisms do not always fit into rigidly defined categories, classifying botanists often disagree as to how broadly the various nomenclatural ranks should be interpreted. For example, a particular group of grasses that appears to constitute a subspecies to one botanist might be judged a species by another. The purple moor grasses, Molinia caerulea (Linnaeus) Moench, are an example of this situation. Most botanists see the differences between the shorter and taller purple moor grasses as warranting recognition only as subspecies, in which case the shorter plants are named M. caerulea subsp. caerulea (Linnaeus) Moench, and the taller plants M. caerulea subsp. arundinacea (Schrank) H. Paul. Other botanists consider the taller plants worthy of recognition as a species, M. arundinacea Schrank. Botanists inclined to nomenclatural recognition of the differences between plants are informally referred to as splitters. Those inclined to broader definitions of taxa are called lumpers.

Swaying-rush, Schoenoplectus subterminalis (Torrey) Sojak, adds its unique patterns to dark Pine Barrens waters in mid September. Despite the well-used common name, this plant is botanically a sedge, not a rush. Originally named by John Torrey and classified in the genus Scirpus, as Scirpus subterminalis Torrey, it is now accepted as belonging in the genus Schoenoplectus.

Swaying-rush, Schoenoplectus subterminalis (Torrey) Sojak, adds its unique patterns to dark Pine Barrens waters in mid September. Despite the well-used common name, this plant is botanically a sedge, not a rush. Originally named by John Torrey and classified in the genus Scirpus, as Scirpus subterminalis Torrey, it is now accepted as belonging in the genus Schoenoplectus.

This topic follows scientifically accepted botanical nomenclature for grasses. The names have been compiled from the most recent world floras, journal articles, and checklists available, including online databases cited in the bibliography. The overall approach is of informed conservation. Name changes and reclassifications have been adopted only when there is genuine evidence of their merits and likely durability. In situations where no definitive nomenclature or classification is available.

Names of Cultivated Plants

Horticulturists are often concerned with differences between plants that are not adequately distinguished by the preceding botanical ranks. The term cul-tivar, derived from cultivated variety, was coined to serve this purpose. The naming of cultivars is governed by the International Code of Nomenclature for Cultivated Plants (ICNCP), which supplements the International Code of Botanical Nomenclature (ICBN).

A cultivar is a group of plants under cultivation selected for one or more distinct characteristics which are uniform, stable, and capable of being retained through appropriate means of propagation. Cultivars may arise by selection from variant individuals in the wild or in cultivation, or through deliberate or accidental hybridization.

Cultivar names are always capitalized. Unlike botanical names, cultivar names are never italicized or underlined; however, they should be enclosed in single quotation marks. Cultivar names are always placed at the end of the botanical name, as in Panicum amarum ‘Dewey Blue’. Especially in popular writing, it is acceptable to drop author citations from botanical names when cultivar names follow. Also, in popular use, it is allowable to drop the species epithet from the botanical name of a cultivar if there is no likelihood of confusion. For example, P. amarum ‘Dewey Blue’ may be abbreviated to P. ‘Dewey Blue’ since the cultivar name ‘Dewey Blue’ has only been assigned to the species P. amarum. If the species of a cultivar is not known or in doubt, the cultivar name follows the genus, as in Miscanthus ‘Purpurascens’.

The use of cultivar names is a relatively recent convention. The first edition of the ICNCP appeared in 1953. Many early cultivar names originated as Latinized names coined in an era when the distinction between horticultural nomenclature and botanical nomenclature was unclear. ‘Gracillimus’ is such aname, as are ‘Aurea’, ‘Variegata’, and ‘Rubra’. Beginning in 1959, ICNCP rules require that all cultivar names must be from words in a modern language; they may not be Latinized. For example, ‘Morning Light’ is an acceptable cultivar name whereas ‘Gracillimus Variegatus’ is not. Beginning in 1995, ICNCP rules do not condone the use of translations of cultivar names. For example, the German miscanthus cultivar name ‘Silberfeder’ should not be translated to ‘Silver Feather’, its English equivalent. Despite the ICNCP, this practice persists in commerce and for this reason.

The ICNCP also includes a rule of priority requiring that the earliest, valid cultivar name be preserved as the correct one. For example, the earliest established cultivar name for Bowles’ golden sedge is Carex elata ‘Aurea’. The name ‘Bowles Golden’ is a later name not acceptable as a cultivar but appropriate as part of the common name: Bowles’ golden sedge.

Panicum amarum 'Dewey Blue' at Chanticleer in Wayne, Pennsylvania, in late June.

Panicum amarum ‘Dewey Blue’ at Chanticleer in Wayne, Pennsylvania, in late June.

Contrary to popular misconception, cultivars are not, by definition, comprised of genetically identical plants (clones). They may be, in which case they are best referred to as clonal cultivars. An example is Panicum virgatum ‘Shenandoah’. This clonal cultivar must be vegetatively propagated if new plants are to retain all distinguishing characteristics, which include relatively short stature and deep red-suffused late-season foliage.

Seed cultivars are not as precisely defined as clonal cultivars, sometimes having only one distinguishing characteristic, and are intended for propagation by seed. Some very loosely defined seed cultivars are maintained by selecting seedlings that match the cultivar description and by rejecting uncharacteristic seedlings. The historic cultivar Miscanthus sinensis ‘Gracillimus’ is often maintained by seed. It has been grown in Western gardens for over a century, defined by its narrow leaves, rounded form, and late-season reddish inflorescences. Most seedlings of ‘Gracillimus’ (unless pollinated by other cul-tivars) are reasonably uniform in these characteristics, even though they are not genetically identical. Over decades, some nurseries have grown ‘Gracillimus’ from seed, rejecting occasional variants, and other nurseries have produced genetically uniform new plants by vegetative division. Plants of M. sinensis ‘Gracillimus’ obtained from ten different sources will look essentially alike, but minor variations will be apparent to keen eyes.


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