Plant Nomenclature by Matt Jenks Purdue University Department of Horticulture and Landscape Architecture Introductory Co

1. Plant Nomenclature by Matt Jenks Purdue University Department of Horticulture and Landscape Architecture Introductory Comments The overall objective of this module is to help you learn about plant nomenclature and classification. The information presented here provides an important foundation for future learning about landscape plants. You will learn principles that govern the proper writing of scientific names (i.e. Latin binomial), skills that are essential for communication within the landscape industry. You will also become familiar with the scientific basis for classifying plants into distinct groupings. Spend time putting as much of this information as possible to memory before moving on. Plant Names Plants can be described using descriptors such as tree, shrub, vine, groundcover, evergreen, deciduous, annual, perennial, woody, herbaceous, hardy, tender, etc. Single word descriptions like these are useful but contribute only little to separating one plant-kind from another. For example, many quite different plants could all be referred to as trees. More thorough descriptions using many words, as was done in early scientific naming systems, are too complex and cumbersome for common usage. Today, each plant kind is given a unique scientific name. Carolus Linnaeus (in his Species Plantarum, 1753) first developed the scientific system we now use to name plants, referred to as the Linnaean Binomial System of Nomenclature. Using this system, plants are given two Latinized names that create a binomial. In the Latin bionomial, the first name is called the genus and the second is called the specific epithet. The genus name and the specific epithet together form the species name. For example, the species name for the North American Sugar Maple is Acer saccharum. The Latin genus Acer is the ancient Latin name for maple (perhaps meaning hard as is the wood), whereas the specific epithet saccharum is latin for sugar or sugar cane. Since few people speak Latin, an obvious question might be, "why not simply use common English names, like Sugar Maple, instead of scientific Latin names?" The primary problem with common names is that they are often commonly used in only localized regions. For example, the Sugar Maple is often called Rock or Hard Maple in different parts of the United States. The American Hornbeam (Carpinus caroliniana) is also called Blue Beech, Musclewood, Water Beech, or Ironwood in various regions. Dirr notes in his Manual of Woody Landscape Plants (1998) that the European White Waterlily (Nymphaea alba) has 15 different common English names, 44 French, 105 German, and 81 Dutch names, a total of over 245 common names. To compound the problem, identical common names in different regions often refer to completely different plants. The potential for confusion in the communications between people living in different geographical regions is obvious. Next Page

2. To standardize plant names around the world, a single species name, a Latin binomial, has been established for each plant according to the International Code of Botanical Nomenclature (ICBN), by the activity of authorities coordinated in part through the International Association for Plant Taxonomy (IAPT). The registering of culivar names is the responsibility of the International Cultivar Registration Authorities (ICRAs). Writing a Species Name The species name (i.e. Latin binomial) is italicized or underlined. The first letter of the genus is in upper case whereas the specific epithet is in all lower case letters. As an example, the species name for Sugar Maple should be written as: Acersaccharum or Acer saccharum A name often following the Latin binomial, as in Acer saccharum Marsh., is the abbreviated name of the individual who first assigned a scientific name to the plant, in this case Humphrey Marshall. The letter "L." in the Latin name Hedera helix L. identifies Linnaeus as the authority. The authority name is not typically included in nursery and landscape literature. The Basis for Species Classification Plants belong to a taxonomic grouping of organisms (taxon) called the Plant Kingdom or Plantae. The Plant Kingdom is progressively subdivided into divisions, classes, orders, families, genera, and then species. Species are often further divided into various types referred to as cultivar, forma, or variety. In a general sense, the plant family and lower taxons are those most useful to landscape horticulturists. A family is a group of related genera (or a single genus) that is separated from other families mainly by differences in the shape and position of their reproductive structures. However, when members of a family are commonly as diverse as vine, shrub, and large tree, or have dramatically different environmental adaptation, the significance of taxonomic groupings can appear remote to many landscape students. The subdividing of families into genera and genera into species based on morphology poses similar problems. To make matters worse, many plants of different species readily hybridize to produce populations of fertile offspring (called hybrids). Despite obvious limitations in current taxonomic approaches, these classification methods provide important order to the incredibly diverse Plant Kingdom. Important Plant Classification Terminology Genus: Weakly defined as a group of plants containing one or more species. The species have more characteristics in common with each other than they do with species of other genera in the same family. Similarity of flowers and fruits is the most widely used feature of comparison. A genus may contain a single species (e.g., Ginkgo biloba) or more than 100 (e.g., Rosa spp.). The plural of the singular genus is genera. Previous Page Next Page

3. Species: A group of individual plants that are fundamentally the same, separated from other closely related species by "distinct" morphological differences. All individuals in a given species are not identical, but can express variation in certain traits (consider how different Humans, Homo sapiens, may appear visually). Species is abbreviated sp. (singular) or spp. (plural). Variety: A population of plants within a species that display clear differences, differences that occur in natural populations. A variety name is written in lower case, italicized or underlined, and preceded by the abbreviation var. For example, Honeylocust is Gleditsia triacanthos whereas the Thornless Honeylocust is Gleditsia triacanthos var. inermis (Latin for lacking thorns). Subspecies (abbreviated ssp.) is for practical purposes equivalent to variety. Forma: Describes sporadic variations, such as an occasional white flowered plant in a population of a normally red-flowered species. For example, Cornus florida is usually white in nature, but pink flowered plants occur naturally, being referred to as Cornus florida f. rubra. Cultivar: A term coined by Liberty Hyde Bailey and derived from the term "cultivated variety". It is defined as an assemblage of cultivated plants, which are clearly distinguished by one or more characters, and which when reproduced (sexually or asexually) retains its distinguishing characteristics. A yellow stem form of Redosier Dogwood is Cornus sericea 'Flaviramea'. The cultivar name is not italicized or underlined and has single quotes on either side of the name. Cultivar is abbreviated cv. so the plant could also be named with the single quotes deleted, such as, Cornus sericea cv. Flaviramea. Patents and Trademarks: Patents give exclusive rights and protection to an inventor to make, use, and sell an invention. For 20 years after the date indicated on a plant patent, only the patent holder may commercially raise or sell a patented plant. Others may do so through license or royalty agreements with the patent holder. Trademarks provide another form of protection. The plant name can be trademarked and such names cannot be used as a name for any other similar plant. Trademarked plant names are indicated by use of a trademark (™), such as Betula nigra Heritage™, whereas patented plants are designated with a registered trademark (®). Confusing to some is the fact that patented cultivars must be given, in addition to the registered trademark name, an official cultivar name registered according to the International Code of Nomenclature for Cultivated Plants (ICNCP). In the case of Betula nigra Heritage™, the actual cultivar name approved by the International Cultivar Registration Authorities (ICRAs) is 'Cully'. Previous Page Nomenclature Practice Quiz

4. Plant Nomenclature Practice Quiz Acer palmatum 1. What is the name of the first term ? Answer Previous Page

5. Plant Nomenclature Practice Quiz Acer palmatum 1. What is the name of the first term ? Genus name 2. What is the name of the second term ? Answer

6. Plant Nomenclature Practice Quiz Acer palmatum 1. What is the name of the first term ? Genus name 2. What is the name of the second term ? Specific epithet 3. Can the species name be written as Acerjaponicum ? Answer

7. Plant Nomenclature Practice Quiz Acer palmatum 1. What is the name of the first term ? Genus name 2. What is the name of the second term ? Specific epithet 3. Can the species name be written as Acerpalmatum ? Yes. Both terms can either be italicized or underlined but not both. The first letter of the genus name is upper case. The specific epithet is all lower case. Next Question

8. Plant Nomenclature Practice Quiz 4. What does sp. and spp. and ssp. represent? Answer

9. Plant Nomenclature Practice Quiz 4. What does sp. and spp. and ssp. represent? sp. stands for species, singular spp. stands for species, plural ssp. stands for subspecies Next Question

10. Plant Nomenclature Practice Quiz 5. The latin name for the Thornless Honeylocust is Gleditsia triacanthos var. inermis. If Gleditisa is the genus name and triacanthos is the species epithet, what does inermis represent? Answer

11. Plant Nomenclature Practice Quiz 5. The latin name for the Thornless Honeylocust is Gleditsia triacanthos var. inermis. If Gleditisa is the genus name and triacanthos is the species epithet, what does inermis represent? The var. before inermis gives the hint. inermis is a variety of Gleditisa triacanthos that is thornless. A variety is a subpopulation within a species that displays a distinct difference from the straight species, in this example thornlessness. This difference is naturally occurring and usually has a distinct geographical range. The variety name is always italicized and preceded by the abbreviation var. which is not italicized. Next Question

12. Plant Nomenclature Practice Quiz 6. What does ‘October Glory’ represent in the name Acer rubrum ‘October Glory’ ? Answer

13. Plant Nomenclature Practice Quiz 6. What does ‘October Glory’ represent in the name Acer rubrum ‘October Glory’ ? ‘October Glory’ is the cultivar name for a type of Red Maple with a brilliant red fall foliage introduced in 1961 by Princeton Nursery. Cultivar names are always enclosed in single quotes and the first letter of each word is always capitalized. The cultivar name is not italicized or underlined. Next Question

14. Plant Nomenclature Practice Quiz 7. What does pendula represent in the latin name Fagus sylvatica f. pendula ? Answer

15. Plant Nomenclature Practice Quiz 7. What does pendula represent in the latin name Fagus sylvatica f. pendula ? pendula is the forma name. A forma designates a variation which occurs sporadically and randomly within the native plant species. Fagus sylvatica f. pendula is the weeping form of the European Beech. Forma name is preceded with a lower case f with a period. The forma name is in lower case and italicized if the species name is italicized or underlined if the species name is underlined. Next Question

16. Plant Nomenclature Practice Quiz 8. What is wrong with the following latin names? a. Cornus florida Answer b. Cercis canadensis ‘Forest Pansy’ Answer c. Acersaccharumvar. nigrum Answer d. Lindera benzoin f. ‘rubra’ Answer

17. Plant Nomenclature Practice Quiz 8. What is wrong with the following species names? a. Cornus florida Answer both terms must be italicized or underlined b. Cercis canadiensis ‘Forest Pansy’ Answer c. Acersaccharumvar. nigrum Answer d. Lindera benzoin f. ‘rubra’ Answer

18. Plant Nomenclature Practice Quiz 8. What is wrong with the following species names? a. Cornus florida Answer both terms must be italicized or underlined b. Cercis canadiensis ‘Forest Pansy’ Answer Cultivar name ‘Forest Pansy’ should not be italicized c. Acersaccharumvar. nigrum Answer d. Lindera benzoin f. ‘rubra’ Answer

19. Plant Nomenclature Practice Quiz 8. What is wrong with the following species names? a. Cornus florida Answer both terms must be italicized or underlined b. Cercis canadiensis ‘Forest Pansy’ Answer Cultivar name ‘Forest Pansy’ should not be italicized c. Acersaccharumvar. nigrum Answer var. should not be underlined d. Lindera benzoin f. ‘rubra’ Answer

20. Plant Nomenclature Practice Quiz 8. What is wrong with the following species names? a. Cornus florida both terms must be italicized or underlined b. Cercis canadiensis ‘Forest Pansy’ Cultivar name ‘Forest Pansy’ should not be italicized c. Acersaccharumvar. nigrum var. should not be underlined d. Lindera benzoin f. ‘rubra’ forma name should not be in single quotes Return to beginning of Practice Test Use Browser’s Back Button to Exit