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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 things).
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.
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.
Plantae, the Plant KingdomEdit
The plant kingdom is divided according to the following:
|Bryophyta||Mosses||No vascular system, distinctive vegetative structures, spores produced for reproduction require damp conditions for survival, many mosses are important to the early stages of soil formation|
|Hepatophyta||Liverworts||Same as mosses|
|Equisetophyta||Horsetails||Identifiable root, leaf and stem systems but still produce spores instead of seed|
|Pteridophyta||Ferns||Same as horsetails|
|Coniferophyta||Conifers||Includes Pinales, Taxales, Cupressaceae and hundreds of other species. Reproduce by producing seeds most often in cones, many have adaptations to tolerate water loss|
|Ginkgophyta||Gingko||Only member is the ginkgo biloba|
|Angiosperms||Flowering plants||Includes around 25,000 species divided into two main classes the monocotyledons and dicotyledons, produce seeds that are protected by fruits|
Identification, classification and description of plantsEdit
Three goals of plant taxonomy are the identification, classification and description of plants. The distinction between these three goals is important and often overlooked.
1.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. The process of identification connects the specimen with a published name. Once a plant specimen has been identified, its name and properties are known.
2.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:
- Kingdom: Plantae
- Division: Magnoliophyta
- Class: Liliopsida
- Order: Liliales
- Family: Liliaceae
- Genus: Pine, Wattles, Milkvetch, Dandelion, etc.
- Species: Common water Hyacinth, Yellow star-thistle, Purple loosestrife, Kudzu, etc.
- Variety: ......
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.
3.Plant description is a formal description of a newly discovered species, usually in the form of a scientific paper using ICN guidelines. The names of these plants are then registered on the International Plant Names Index along with all other validly published names.
- APG system (angiosperm phylogeny group)
- Bessey system (a system of plant taxonomy)
- Cronquist system (taxonomic classification of flowering plants)
- Melchior system
- Principles of Horticulture, 4th Ed. Elsevier. p. 28.