Classification and Naming of Plants

® EXTENSION Know how. Know now. EC1272 Classification and Naming of Plants Anne M. Streich, Associate Professor of Practice Kim A. Todd, Extension Landscape Specialist Extension is a Division of the Institute of Agriculture and Natural Resources at the University of Nebraska–Lincoln cooperating with the Counties and the United States Department of Agriculture. University of Nebraska–Lincoln Extension educational programs abide with the nondiscrimination policies of the University of Nebraska–Lincoln and the United States Department of Agriculture. © 2014, The Board of Regents of the University of Nebraska on behalf of the University of Nebraska–Lincoln Extension. All rights reserved. Classification and Naming of Plants Anne M. Streich, Associate Professor of Practice Kim A. Todd, Extension Landscape Specialist Classifying organisms based on similarities helps provide order to the thousands of living organisms on earth. By understanding the classification system, gardeners and profes- sional landscape managers can make appropriate decisions for propagat- ing, controlling, or managing landscape plants. Properly naming plants through careful classification allows professionals and gardeners to eas- a b ily communicate with each other and with others across the world without Figure 1. Common names are frequently used when talking about plants. being confused by common names Unfortunately, confusion occurs when multiple common names are used (Figure 1). for the same plant or a common name is used for more than one plant. Geranium is a common example. Most people think of the well-known Classification of Plants annual (Pelargonium X hortum) that often has large clusters of red, pink or white flowers as geranium (a). But Geranium is also the genus for a lesser-known perennial which has smaller, single flowers in shades of Taxonomy is the science of iden- pink and purple and different foliage characteristics (b). Using scientific tifying, classifying, and naming organ- names eliminates the potential confusion that occurs when communicat- isms. In 1735, Carl Linnaeus created a ing about plants. hierarchical classification system that places all organisms into successively smaller groups that assume organisms and specific epithet, which together continues to evolve. Plants are occa- within a specific group resemble one define the species. Before the binomial sionally moved from one classifica- another more than organisms within system was adopted, plants could have tion to another or names are slightly a different group. His system classified very long scientific names that could changed to reflect new knowledge. plants based on sexual reproductive be easily changed. With the binomial These changes can be observed in text- parts. Other plant classification systems system, there can be several common books. used different morphological charac- names for a single plant, but there is teristics, such as leaf and stem qualities, only one official scientific Latin name. to classify plants. Linnaeus’ basic clas- The scientific binomial naming system Kingdoms sification method is still used today. The is governed by the International Code classification system groups, in order of Nomenclature. from largest to smallest, are kingdom, Kingdom is the broadest divi- phylum or division, class, order, family, Systematics is an emerging sci- sion of organisms. Linnaeus originally genus, and species (Figure 2). ence that uses today’s technology to divided all organisms into two king- classify plants based on evolutionary doms — the Plant Kingdom and the Linnaeus also described a bino- relationships that can be identified Animal Kingdom. With new knowl- mial naming system. All organisms through molecular sciences. With this edge and discovery, this classification were given two names — the genus new technology, plant classification system was expanded to five kingdoms © The Board of Regents of the University of Nebraska. All rights reserved. 3 in the 1900s, and more recently into six kingdoms. Organisms are differen- tiated into kingdoms based on various characteristics including the number Species ~ 300,00 of cells (one to multicellular), cell type (complex or simple), presence or absence of cell walls and/or organelles, Genus ~ 16,167 and the ability to make their own food. The six kingdoms recognized today are described below. Family ~ 620 • Plant Kingdom. Plants are multicellular, have complex cell walls, are primarily immotile, and make Order their own food. Organisms that make their own food are called au- totrophs. More information about the processes plants use to create Class food can be found in EC1268, Plant Growth Processes: Transpira- tion, Photosynthesis, and Respira- tion. Without plants, life on earth Division would not exist. Humans and other heterotrophs (organisms that cannot use atmospheric CO2 to create complex organic mole- Plant Kingdom cules) rely on plants for their food. The plant kingdom is the second Figure 2. Plant kingdom contains all the known plants, approximately largest kingdom and contains 300,000 plant species. As plants are classified into divisions, classes, an estimated 300,000 plant spe- orders, families, and genera more specific groupings of plants are cies. Within the plant kingdom, found until each plant is specifically named. plants are further categorized into non-vascular and vascular plants. Non-vascular plants do not contain water-conducting tissues or landscapes are beneficial because considered delicacies. For more true roots, leaves, or stems. Plants of their pollination or preda- detailed information about plant with non-vascular systems include tory activities. For more detailed diseases, see EC1273, Introduction mosses and liverworts. Vascular information about insect classifi- to Plant Diseases. plant systems contain water and cation see EC1588, Introduction to nutrient conducting tissues called Entomology. EC1260, Landscape • Protista Kingdom. Most Protista xylem and phloem. Vascular plants Diagnostic Guide for Problems are unicellular, complex cells that have true roots, stems, and leaves Affecting Woody Ornamentals and acquire nutrients through pho- (Figure 3). Herbaceous Perennials provides tosynthesis or by eating other information on signs and symp- organisms. This kingdom includes • Animal Kingdom. Animals are toms of common vertebrate pests a variety of microscopic organ- multicellular, consist of complex in home landscapes. isms that vary quite a bit from one cells, and rely on plants for their another, unlike organisms in the food. The animal kingdom is the • Fungi Kingdom. Fungi are pri- other five kingdoms. Slime molds largest kingdom. It has more than marily multicellular, complex and algae are in the Protista king- a million species, with more than cells, but they do not make their dom. three-fourths of all species being own food. They usually obtain arthropods (primarily insects). In food from decaying organisms. • Eubacteria Kingdom. Eubacteria landscapes, wildlife and insects Fungi are often the causal agent are complex, unicellular organ- are the primary animals of inter- of many plant diseases. However, isms. Most bacteria are in this est, and many insects found in many fungi, including morels, are kingdom. Bacteria have various 4 © The Board of Regents of the University of Nebraska. All rights reserved. Plant Kingdom b Non-vascular Plants Vascular Plants No root, stem Structures look Spore Producer Seed Producer or leaf-like like root, stem, Ferns structures or leaf Flowers No Flowers Algae Moss Angiosperms Gymnosperms One Seed Leaf Two Seed Leaves Monocot Dicot Figure 3. All members of the plant kingdom can be classified based on their morphological differences. Some biologists classify algae in the Protista kingdom, while other plant biologists would classify them as the sim- plest member of the plant kingdom. cultivar , hybrid, and authority nota- monocotyledons or dicotyledons functions, including being causal tions. (Figure 4). agents for some plant diseases, biological control agents for some • Plant Division. Plant divisions ■ Monocotyledons (monocots) pests, nitrogen fixers in some classify plants based on whether include grasses, iris, lilies, or- plant species (legumes), and serv- they reproduce by spores or seeds. chids, and yuccas. Distinguish- ing as the primary organic matter Spore-bearing plants include ing characteristics include one decomposers in the soil. Bacteria ferns, club mosses, and horsetail. seed leaf, a vascular system in can live in environments that have Seed-bearing plants are divided paired bundles throughout the (aerobic) or lack (anaerobic) oxy- into gymnosperms and angio- stem, floral parts in multiples gen for respiration. sperms. of three, and parallel leaf veins. Meristematic regions, areas of • Archaea Kingdom. Archaea are ■ Gymnosperms are non- plant growth, are low in the unicellular organisms found in flowering plants that produce plant until vegetative growth extreme environments, such as naked seeds. Cycads, ginkgo, changes to reproductive very hot springs or highly acidic and conifers, such as pines growth. or alkaline waters. Archaea is and spruce, are examples of the last kingdom discovered and gymnosperms. There are 700 ■ Dicotyledons (dicots) have new knowledge about where estimated gymnosperm species distinguishing characteristics these organisms live is still being in existence today. including two seed leaves, discovered. vascular systems arranged in ■ Angiosperms are flowering continuous rings around the plants that have their seeds inside of the stem,

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