Plant taxonomy

Short description: Scientific study of identifying, classifying, describing, and naming plants

"Systematic botany" redirects here. For the scientific journal, see Systematic Botany.

Plant taxonomy is the science that finds, identifies, describes, classifies, and names plants. It is one of the main branches of taxonomy—the science that finds, describes, classifies, and names living organisms.

Plant taxonomy is closely allied to plant systematics, and there is no sharp boundary between the two. In practice, "plant systematics" involves relationships between plants and their evolution, especially at the higher levels, whereas "plant taxonomy" deals with the actual handling of plant specimens. The precise relationship between taxonomy and systematics, however, has changed along with the goals and methods employed.

Plant taxonomy is well known for being turbulent, and traditionally not having any close agreement on circumscription and placement of taxa. See the list of systems of plant taxonomy.

## Contents

* 1 Background
* 1.1 History of classification
* 2 Plantae, the Plant Kingdom
* 3 Identification, classification and description of plants
* 4 Classification systems
* 5 Online databases
* 6 See also
* 7 References
* 8 Sources
* 9 External links

## Background

Classification systems serve the purpose of grouping organisms by characteristics common to each group. Plants are distinguished from animals by various traits: they have cell walls made of cellulose, polyploidy, and they exhibit sedentary growth. Where animals have to eat organic molecules, plants are able to change energy from light into organic energy by the process of photosynthesis. The basic unit of classification is species, a group able to breed amongst themselves and bearing mutual resemblance, a broader classification is the genus. Several genera make up a family, and several families an order.[1]

### History of classification

The botanical term angiosperm, or flowering plant, comes from the Greek angeíon (ἀγγεῖον; 'bottle, vessel') and spérma (σπέρμα; 'seed'); in 1690, the term Angiospermae was coined by Paul Hermann, albeit in reference to only a small subset of the species that are known as angiosperms, today. Hermann's Angiospermae included only flowering plants possessing seeds enclosed in capsules, distinguished from his Gymnospermae, which were flowering plants with achenial or schizo-carpic fruits (the whole fruit, or each of its pieces, being here regarded as a seed and naked). The terms Angiospermae and Gymnospermae were used by Carl Linnaeus in the same sense, albeit with restricted application, in the names of the orders of his class Didynamia.[2]

The terms angiosperms and gymnosperm fundamentally changed meaning in 1827, when Robert Brown determined the existence of truly-naked ovules in the Cycadeae and Coniferae.[3] The term gymnosperm was, from then-on, applied to seed plants with naked ovules, and the term angiosperm to seed plants with enclosed ovules. However, for many years after Brown's discovery, the primary division of the seed plants was seen as between monocots and dicots, with gymnosperms as a small subset of the dicots.[4]

In 1851, Hofmeister discovered the changes occurring in the embryo-sac of flowering plants, and determined the correct relationships of these to the Cryptogamia. This fixed the position of Gymnosperms as a class distinct from Dicotyledons, and the term Angiosperm then, gradually, came to be accepted as the suitable designation for the whole of the flowering plants (other than Gymnosperms), including the classes of Dicotyledons and Monocotyledons.[4] This is the sense in which the term is used, today.[5]

In most taxonomies, the flowering plants are treated as a coherent group; the most popular descriptive name has been Angiospermae, with Anthophyta (lit. flower-plants) a second choice (both unranked). The Wettstein system and Engler system treated them as a subdivision (Angiospermae). The Reveal system also treated them as a subdivision (Magnoliophytina),[6] but later split it to Magnoliopsida, Liliopsida, and Rosopsida. The Takhtajan system and Cronquist system treat them as a division (Magnoliophyta). The Dahlgren system and Thorne system (1992) treat them as a class (Magnoliopsida). The APG system of 1998, and the later 2003[7] and 2009[8] revisions, treat the flowering plants as an unranked clade without a formal Latin name (angiosperms). A formal classification was published alongside the 2009 revision in which the flowering plants rank as a subclass (Magnoliidae).[9]

The internal classification of this group has undergone considerable revision. The Cronquist system, proposed by Arthur Cronquist in 1968 and published in its full form in 1981, is still widely used but is no longer believed to accurately reflect phylogeny. A consensus about how the flowering plants should be arranged has recently begun to emerge through the work of the Angiosperm Phylogeny Group (APG), which published an influential reclassification of the angiosperms in 1998. Updates incorporating more recent research were published as the APG II system in 2003,[7] the APG III system in 2009,[8][10] and the APG IV system in 2016.

Traditionally, the flowering plants are divided into two groups,

* Dicotyledoneae or Magnoliopsida
* Monocotyledoneae or Liliopsida

## Plantae, the Plant Kingdom

The plant kingdom is traditionally divided according to the following:

Latin  | Common  | No. of species  | Notes

|
|
|

Bryophyta | Mosses  | approx. 25,000  | No vascular system, distinctive vegetative structures, spores produced for reproduction require damp conditions for survival, many of them are important to the early stages of soil formation.
Pteridophyta | Ferns  | approx. 13,000  | Identifiable root, leaf and stem systems but still produce spores instead of seed.
Gymnosperms | Non-flowering seed plant  | approx. 1,000  | They are a group of seed producing plants, which include Coniferophyta, Ginkgophyta, Cycadophyta and Gnetophyta.
Angiosperms | Flowering plants  | approx. 300,000  | They are divided into two main classes the monocotyledons and dicotyledons, produce seeds that are protected by fruits.

## Identification, classification and description of plants

Three goals of plant taxonomy are the identification, classification and description of plants. The distinction between these three goals is important and often overlooked.

Plant identification is a determination of the identity of an unknown plant by comparison with previously collected specimens or with the aid of books or identification manuals.[11] The process of identification connects the specimen with a published name. Once a plant specimen has been identified, its name and properties are known.

Plant classification is the placing of known plants into groups or categories to show some relationship. Scientific classification follows a system of rules that standardizes the results, and groups successive categories into a hierarchy. For example, the family to which the lilies belong is classified as follows:[12]

* Kingdom: Plantae
* Division: Magnoliophyta
* Class: Liliopsida
* Order: Liliales
* Family: Liliaceae

The classification of plants results in an organized system for the naming and cataloging of future specimens, and ideally reflects scientific ideas about inter-relationships between plants. The set of rules and recommendations for formal botanical nomenclature, including plants, is governed by the International Code of Nomenclature for algae, fungi, and plants abbreviated as ICN.[13]

Plant description is a formal description of a newly discovered species, and takes place only after significant scientific work to determine that a species is in fact new to science. New descriptions are usually published in the form of a scientific paper using ICN guidelines.[14] The names of these plants can then be registered to the International Plant Names Index along with other validly published names.[15]

## Classification systems

Main article: Biology:List of systems of plant taxonomy

These include;

* APG system (angiosperm phylogeny group)
* APG II system (angiosperm phylogeny group II)
* APG III system (angiosperm phylogeny group III)
* APG IV system (angiosperm phylogeny group IV)
* Bessey system (a system of plant taxonomy)
* Cronquist system (taxonomic classification of flowering plants)
* Melchior system

## Online databases

* Plants of the World Online (POWO)
* World Flora Online (WFO)
* Ecocrop
* EPPO Code
* GRIN

See Category: Online botany databases

## See also

* American Society of Plant Taxonomists
* Biophysical environment
* Botanical nomenclature
* Citrus taxonomy
* Environmental protection
* Herbarium
* History of plant systematics
* International Association for Plant Taxonomy
* Taxonomy of cultivated plants

## References

1. ↑ Principles of Horticulture, 4th Ed.. Elsevier. p. 28.
2. ↑ Chisholm 1911, p. 9.
3. ↑ Brown, Robert (1827). "Character and description of Kingia, a new genus of plants found on the southwest coast of New Holland: with observations on the structure of its unimpregnated ovulum; and on the female flower of Cycadeae and Coniferae". in King, Philip Parker. Narrative of a Survey of the Intertropical and Western Coasts of Australia: Performed Between the Years 1818 and 1822. J. Murray. pp. 534–565. OCLC 185517977. https://books.google.com/books?id=RjdCAAAAIAAJ&pg=PA534.
4. ↑ 4.0 4.1 Buggs, Richard J.A. (January 2021). "The origin of Darwin's 'abominable mystery'". American Journal of Botany 108 (1): 22–36. doi:10.1002/ajb2.1592. PMID 33482683.
5. ↑ Chisholm 1911, p. 10.
6. ↑ Frohne & Jensen ex Reveal (29 April 1996). "Magnoliophytina". Phytologia. 79 (2): 70.
7. ↑ 7.0 7.1 APG 2003.
8. ↑ 8.0 8.1 APG 2009.
9. ↑ Chase & Reveal 2009.
10. ↑ "As easy as APG III – Scientists revise the system of classifying flowering plants" (Press release). The Linnean Society of London. 8 October 2009. Archived from the original on 26 November 2010. Retrieved 2 October 2009.
11. ↑ Lawrence, George H. M. (1955). An Introduction to Plant Taxonomy. The Macmilian Company. pp. 84–86. ISBN 9780023681202. http://dspace.kottakkalfarookcollege.edu.in:8001/jspui/bitstream/123456789/5834/1/An Introduction to Plant Taxonomy ( PDFDrive ).pdf.
12. ↑ Schoch, CL (2020). "Taxonomy browser (Liliaceae)". https://www.ncbi.nlm.nih.gov/Taxonomy/Browser/wwwtax.cgi?mode=Info&id=4677&lvl=3&lin=f&keep=1&srchmode=1&unlock.
13. ↑ "International Code of Nomenclature for algae, fungi, and plants" (in en-GB). https://www.iapt-taxon.org/nomen/main.php.
14. ↑ "Operation Wallacea | How is a new species described?" (in en-GB). https://www.opwall.com/article/how-is-a-new-species-described/.
15. ↑ "International Plant Names Index". https://www.ipni.org/.

## Sources

* This article incorporates text from a publication now in the public domain: Chisholm, Hugh, ed (1911). "Angiosperms". Encyclopædia Britannica (11th ed.). Cambridge University Press.
* APG (2003). "An update of the Angiosperm Phylogeny Group classification for the orders and families of flowering plants: APG II". Botanical Journal of the Linnean Society 141 (4): 399–436. doi:10.1046/j.1095-8339.2003.t01-1-00158.x.
* APG (2009). "An update of the Angiosperm Phylogeny Group classification for the orders and families of flowering plants: APG III". Botanical Journal of the Linnean Society 161 (2): 105–121. doi:10.1111/j.1095-8339.2009.00996.x.
* Chase, Mark W.; Reveal, James L. (2009). "A phylogenetic classification of the land plants to accompany APG III". Botanical Journal of the Linnean Society 161 (2): 122–127. doi:10.1111/j.1095-8339.2009.01002.x.

## External links

* Plant systematics
* Tracking Plant Taxonomy Updates discussion group on Facebook

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Botany

History of botany

Subdisciplines|

* Plant systematics
* Ethnobotany
* Paleobotany
* Plant anatomy
* Plant ecology
* Phytogeography
* Geobotany
* Flora
* Phytochemistry
* Plant pathology
* Bryology
* Phycology
* Floristics
* Dendrology
* Astrobotany

Plant groups|

* Algae
* Archaeplastida
* Bryophyte
* Non-vascular plants
* Vascular plants
* Spermatophytes
* Pteridophyte
* Gymnosperm
* Angiosperm

Plant morphology
(glossary)

| Plant cells|

* Cell wall
* Phragmoplast
* Plastid
* Plasmodesma
* Vacuole

|

Tissues|

* Meristem
* Vascular tissue
* Vascular bundle
* Ground tissue
* Mesophyll
* Cork
* Wood
* Storage organs

Vegetative|

* Root
* Rhizoid
* Bulb
* Rhizome
* Shoot
* Stem
* Leaf
* Petiole
* Cataphyll
* Bud
* Sessility

Reproductive
(Flower)|

* Flower development
* Inflorescence
* Umbel
* Raceme
* Bract
* Pedicellate
* Flower
* Aestivation
* Whorl
* Floral symmetry
* Floral diagram
* Floral formula
* Receptacle
* Hypanthium (Floral cup)
* Perianth
* Tepal
* Petal
* Sepal
* Sporophyll
* Gynoecium
* Ovary
* Ovule
* Stigma
* Archegonium
* Androecium
* Stamen
* Staminode
* Pollen
* Tapetum
* Gynandrium
* Gametophyte
* Sporophyte
* Plant embryo
* Fruit
* Fruit anatomy
* Berry
* Capsule
* Seed
* Seed dispersal
* Endosperm

Surface structures|

* Epicuticular wax
* Plant cuticle
* Epidermis
* Stoma
* Nectary
* Trichome
* Prickle

* Plant physiology
* Materials

* Nutrition
* Photosynthesis
* Chlorophyll
* Plant hormone
* Transpiration
* Turgor pressure
* Bulk flow
* Aleurone
* Phytomelanin
* Sugar
* Sap
* Starch
* Cellulose

Plant growth and habit|

* Secondary growth
* Woody plants
* Herbaceous plants
* Habit
* Vines
* Lianas
* Shrubs
* Subshrubs
* Trees
* Succulent plants

Reproduction

* Evolution
* Ecology

* Alternation of generations
* Sporangium
* Spore
* Microsporangia
* Microspore
* Megasporangium
* Megaspore
* Pollination
* Artificial
* Pollinators
* Pollen tube
* Self
* Double fertilization
* Germination
* Evolutionary development
* Evolutionary history
* timeline

Plant taxonomy|

* History of plant systematics
* Herbarium
* Biological classification
* Botanical nomenclature
* Botanical name
* Correct name
* Author citation
* International Code of Nomenclature for algae, fungi, and plants (ICN)
* International Code of Nomenclature for Cultivated Plants (ICNCP)
* Taxonomic rank
* International Association for Plant Taxonomy (IAPT)
* Plant taxonomy systems
* Cultivated plant taxonomy
* Citrus taxonomy
* cultigen
* cultivar
* Group
* grex

Practice|

* Agronomy
* Floriculture
* Forestry
* Horticulture

* Lists
* Related topics

* Botanical terms
* Botanists
* by author abbreviation
* Botanical expedition

* Category
*   * WikiProject

* v
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Taxonomy of...

Life|

| Monophyletic|

* Bacteria
* Plantae
* Allium
* Liliaceae
* Tulipa
* Narcissus
* Orchidaceae
* Triticum
* Adenanthos
* Banksia
* B. integrifolia
* Cactaceae
* Citrus
* Drosera
* Pachypodium
* Araneae
* Scorpiones
* Dermaptera
* Anopheles
* Lepidoptera
* Lucanidae
* Lemuridae
* Homo sapiens

|

Polyphyletic|

* Protists
* Cultivated plants
* Commonly fossilised invertebrates

Other|

* Viruses

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