Cork cambium

Cork cambium is a tissue found in many vascular plants as part of the periderm. The cork cambium is a lateral meristem and is responsible for secondary growth that replaces the epidermis in roots and stems. It is found in woody and many herbaceous dicots, gymnosperms and some monocots, which usually lack secondary growth.

Cork cambium is one of the plant's meristems - the series of tissues consisting of embryonic (incompletely differentiated) cells from which the plant grows. It is one of the many layers of bark, between the cork and primary phloem. The function of cork cambium is to produce the cork, a tough protective material.

Synonyms for cork cambium are bark cambium, pericambium or phellogen. Phellogen is defined as the meristematic cell layer responsible for the development of the periderm. Cells that grow inwards from the phellogen are termed phelloderm, and cells that develops outwards are termed phellem or cork (note similarity with vascular cambium). The periderm thus consist of three different layers;

• phelloderm,
• phellogen (cork cambium) and
• phellem.

Growth and development of cork cambium is very variable between different species, and also highly dependent on age, growth conditions etc. as can be observed from the different surfaces of bark; smooth, fissured, tesselated, scaly, flaking off, etc.

Economic importance

• Commercial cork is derived from the bark of the cork oak (Quercus suber). Cork has many uses including wine bottle stoppers, bulletin boards, coasters, hot pads to protect tables from hot pans, insulation, sealing for lids, flooring, gaskets for engines, fishing bobbers, handles for fishing rods and tennis rackets, etc.
• Many types of bark are used as mulch.

See also

• Meristem
• Cork (material)

References

• Junikka, L. (1994) Macroscopic bark terminology. IAWA Journal 15(1): 3-45
• Trockenbrodt, M. (1990) Survey and discussion of the terminology used in bark anatomy. IAWA Bulletin, New Series 11: 141-166.

For other meanings, see Botany (disambiguation)

Pinguicula grandiflora commonly known as a Butterwort

File:Stem-cross-section.jpg

Example of a cross section of a stem

Botany is the scientific study of plant life. As a branch of biology, it is also called plant science(s), phytology, or plant biology. Botany covers a wide range of scientific disciplines that study plants, algae, and fungi including: structure, growth, reproduction, metabolism, development, diseases, and chemical properties and evolutionary relationships between the different groups. The study of plants and botany began with tribal lore, used to identify edible, medicinal and poisonous plants, making botany one of the oldest sciences. From this ancient interest in plants, the scope of botany has increased to include the study of over 550,000 kinds or species of living organisms.

Scope and importance of botany

Hibiscus

As with other life forms in biology, plant life can be studied from different perspectives, from the molecular, genetic and biochemical level through organelles, cells, tissues, organs, individuals, plant populations, and communities of plants. At each of these levels a botanist might be concerned with the classification (taxonomy), structure (anatomy and morphology), or function (physiology) of plant life.

Historically, botany covers all organisms that were not considered to be animals. Some of these "plant-like" organisms include fungi (studied in mycology), bacteria and viruses (studied in microbiology), and algae (studied in phycology). Most algae, fungi, and microbes are no longer considered to be in the plant kingdom. However, attention is still given to them by botanists, and bacteria, fungi, and algae are usually covered in introductory botany courses.

The study of plants has importance for a number of reasons. Plants are a fundamental part of life on earth. They generate the oxygen, food, fibres, fuel and medicine that allow higher life forms to exist. Plants also absorb carbon dioxide through photosynthesis, a minor greenhouse gas that in large amounts can effect global climate. It is believed that the evolution of plants has changed the global atmosphere of the earth early in the earth's history and paleobotanists study ancient plants in the fossil record. A good understanding of plants is crucial to the future of human societies as it allows us to:

• Produce food to feed an expanding population
• Understand fundamental life processes
• Produce medicine and materials to treat diseases and other ailments
• Understand environmental changes more clearly

Human nutrition

Nearly all the food we eat comes (directly and indirectly) from plants like this American long grain rice.

Virtually all foods eaten come from plants, either directly from staple foods and other fruit and vegetables, or indirectly through livestock or other animals, which rely on plants for their nutrition. Plants are the fundamental base of nearly all food chains because they use the energy from the sun and nutrients from the soil and atmosphere and convert them into a form that can be consumed and utilized by animals, this is what ecologists call the first trophic level. Botanists also study how plants produce food we can eat and how to increase yields and therefore their work is important in mankind's ability to feed the world and provide food security for future generations, for example through plant breeding. Botanists also study weeds, plants which are considered to be a nuisance in a particular location. Weeds are a considerable problem in agriculture, and botany provides some of the basic science used to understand how to minimize 'weed' impact in agriculture and native ecosystems. Ethnobotany is the study of the relationships between plants and people.

Gregor Mendel laid the foundations of modern genetics from his studies of plants.

Fundamental life processes

Plants are convenient organisms in which fundamental life processes (like cell division and protein synthesis for example) can be studied, without the ethical dilemmas of studying animals or humans. The genetic laws of inheritance were discovered in this way by Gregor Mendel, who was studying the way pea shape is inherited. What Mendel learned from studying plants has had far reaching benefits outside of botany. Additionally, Barbara McClintock discovered 'jumping genes' by studying maize. These are a few examples that demonstrate how botanical research has an ongoing relevance to the understanding of fundamental biological processes.

Medicine and materials

Many medicinal and recreational drugs, like cannabis, caffeine, and nicotine come directly from the plant kingdom. Aspirin, which originally came from the bark of willow trees, is just one example. There may be many novel cures for diseases provided by plants, waiting to be discovered. Popular stimulants like coffee, chocolate, tobacco, and tea also come from plants. Most alcoholic beverages come from fermenting plants such as barley malt and grapes.

Plants also provide us with many natural materials, such as cotton, wood, paper, linen, vegetable oils, some types of rope, and rubber. The production of silk would not be possible without the cultivation of the mulberry plant. Sugarcane, rapeseed, soy and other plants with a highly-fermentable sugar or oil content have recently been put to use as sources of biofuels, which are important alternatives to fossil fuels, see biodiesel.

Environmental changes

Plants can also help us understand changes in on our environment in many ways.

• Understanding habitat destruction and species extinction is dependent on an accurate and complete catalog of plant systematics and taxonomy.
• Plant responses to ultraviolet radiation can help us monitor problems like the ozone depletion.
• Analyzing pollen deposited by plants thousands or millions of years ago can help scientists to reconstruct past climates and predict future ones, an essential part of climate change research.
• Recording and analyzing the timing of plant life cycles are important parts of phenology used in climate-change research.
• Lichens, which are sensitive to atmospheric conditions, have been extensively used as pollution indicators.

In many different ways, plants can act a little like the 'miners canary', an early warning system alerting us to important changes in our environment. In addition to these practical and scientific reasons, plants are extremely valuable as recreation for millions of people who enjoy gardening, horticultural and culinary uses of plants every day.

Etymology

From Greek βοτάνη = "pasture, grass, fodder", perhaps via the idea of a livestock keeper needing to know which plants are safe for livestock to eat.

History

The traditional tools of a botanist.

Early examples of plant taxonomy occur in the Rigveda, that divides plants into Vrska (tree), Osadhi (herbs useful to humans) and Virudha (creepers). which are further subdivided. The Atharvaveda divides plants into eight classes, Visakha (spreading branches), Manjari (leaves with long clusters), Sthambini (bushy plants), Prastanavati (which expands); Ekasrnga (those with monopodial growth), Pratanavati (creeping plants), Amsumati (with many stalks), and Kandini (plants with knotty joints). The Taittiriya Samhita and classifies the plant kingdom into vrksa, vana and druma (trees), visakha (shrubs with spreading branches), sasa (herbs), amsumali (a spreading or deliquescent plant), vratati (climber), stambini (bushy plant), pratanavati (creeper), and alasala (those spreading on the ground).

Manusmriti proposed a classification of plants in eight major categories. Charaka Samhitā and Sushruta Samhita and the Vaisesikas also present an elaborate taxonomy.

Parashara, the author of Vrksayurveda (the science of life of trees), classifies plants into Dvimatrka (Dicotyledons) and Ekamatrka (Monocotyledons). These are further classified into Samiganiya (Fabaceae), Puplikagalniya (Rutaceae), Svastikaganiya (Cruciferae), Tripuspaganiya (Cucurbitaceae), Mallikaganiya (Apocynaceae), and Kurcapuspaganiya (Asteraceae). [1]

Among the earliest of botanical works, written around 300 B.C., are two large treatises by Theophrastus: On the History of Plants (Historia Plantarum) and On the Causes of Plants. Together these books constitute the most important contribution to botanical science during antiquity and on into the Middle Ages. The Roman medical writer Dioscorides provides important evidence on Greek and Roman knowledge of medicinal plants.

In ancient China, the recorded listing of different plants and herb concoctions for pharmaceutical purposes spans back to at least the Warring States (481 BC-221 BC). Many Chinese writers over the centuries contributed to the written knowledge of herbal pharmaceutics. There was the Han Dynasty (202 BC-220 AD) written work of the Huangdi Neijing and the famous pharmacologist Zhang Ji of the 2nd century. There was also the 11th century scientists and statesmen Su Song and Shen Kuo, who compiled treatises on herbal medicine and included the use of mineralogy.

Important medieval works of plant physiology include the Prthviniraparyam of Udayana, Nyayavindutika of Dharmottara, Saddarsana-samuccaya of Gunaratna, and Upaskara of Sankaramisra. [2]

In 1665, using an early microscope, Robert Hooke discovered cells in cork, and a short time later in living plant tissue. The German Leonhart Fuchs, the Swiss Conrad von Gesner, and the British authors Nicholas Culpeper and John Gerard published herbals that gave information on the medicinal uses of plants.

In 1754 Carl von Linné (Carl Linnaeus) devided the plant Kingdom into 25 classes. One, the Cryptogamia, included all the plants with concealed reproductive parts (algae, fungi, mosses and liverworts and ferns).

Modern botany

A considerable amount of new knowledge today is being generated from studying model plants like Arabidopsis thaliana. This weedy species in the mustard family was one of the first plants to have its genome sequenced. The sequencing of the rice (Oryza sativa) genome and a large international research community have made rice the de facto cereal/grass/monocot model. Another grass species, Brachypodium distachyon is also emerging as an experimental model for understanding the genetic, cellular and molecular biology of temperate grasses. Other commercially-important staple foods like wheat, maize, barley, rye, pearl millet and soybean are also having their genomes sequenced. Some of these are challenging to sequence because they have more than two haploid (n) sets of chromosomes, a condition known as polyploidy, common in the plant kingdom. Chlamydomonas reinhardtii (a single-celled, green alga) is another plant model organism that has been extensively studied and provided important insights into cell biology.

In 1998 the Angiosperm Phylogeny Group published a phylogeny of flowering plants based on an analysis of DNA sequences from most families of flowering plants. As a result of this work, major questions such as which families represent the earliest branches in the genealogy of angiosperms are now understood. Investigating how plant species are related to each other allows botanists to better understand the process of evolution in plants.

Subdisciplines of Botany

• Agronomy—Application of plant science to crop production
• Bryology—Mosses, liverworts, and hornwarts
• Economic botany—The place of plants in economics
• Ethnobotany—Relationship between humans and plants
• Forestry—Forest management and related studies
• Horticulture—Cultivated plants
• Paleobotany—Fossil plants
• Palynology—Pollen and spores
• Phycology - Algae
• Phytochemistry—Plant secondary chemistry and chemical processes
• Phytomorphology—Structure and life cycles
• Plant anatomy—Cell and tissue structure
• Plant ecology—Role of plants in the environment
• Plant genetics—Genetic inheritance in plants
• Plant pathology—Plant diseases
• Plant systematics—Classification and naming of plants

See also

Crantz's Classis cruciformium..., 1769

• History of plant systematics
• History of phycology
• Botanical garden and List of botanical gardens
• Dendrochronology
• List of domesticated plants
• Edible Flowers
• Flowers and List of flowers
• Forestry
• Herbs
• List of botanical journals
• List of botanists
• List of botanists by author abbreviation
• List of systems of plant taxonomy
• List of publications in biology
• Paleobotany
• Palynology
• Plant anatomy
• Seeds
• Plant physiology
• Plant community
• Plant sexuality
• Soil science

• Trees
• Vegetation
• Weed Science

References

• U.S. Geological Survey. National Biological Information Infrastructure: Botany

Further reading

Popular science style books on Botany

• Attenborough, David The Private Life of Plants, ISBN 0-563-37023-8
• Bellamy, D Bellamy on Botany, ISBN 0-563-10666-2 an accessible and short introduction to various botanical subjects
• Capon, B: Botany for Gardeners ISBN 0-88192-655-8
• Cohen, J. How many people can the earth support? W.W. Norton 1995 ISBN 0-393-31495-2
• Halle, Francis. In praise of plants ISBN 0-88192-550-0. English translation of a poetic advocacy of plants.
• King, J. Reaching for the sun: How plants work ISBN 0-521-58738-7. A fluent introduction to how plants work.
• Pakenham, T: Remarkable Trees of the World (2002) ISBN 0-297-84300-1
• Pakenham, T: Meetings with Remarkable Trees (1996) ISBN 0-297-83255-7
• Pollan, M The Botany of Desire: A Plant's-eye View of the World Bloomsbury ISBN 0-7475-6300-4 Account of the co-evolution of plants and humans
• Thomas, B.A.: The evolution of plants and flowers St Martin's Press 1981 ISBN 0-312-27271-5
• Walker, D. Energy, Plants and Man ISBN 1-870232-05-4 A presentation of the basic concepts of photosynthesis

Academic and Scientific books on Botany

• Buchanan, B.B., Gruissem, W & Jones, R.L. (2000) Biochemistry & molecular biology of plants. American Society of Plant Physiologists ISBN 0-943088-39-9
• Crawford, R. M. M. (1989). Studies in plant survival. Blackwell. ISBN 0-632-01475-X
• Crawley, M. J. (1997). Plant ecology. Blackwell Scientific. ISBN 0-632-03639-7
• Ennos, R and Sheffield, E Plant life, Blackwell Science, ISBN 0-86542-737-2 Introduction to plant biodiversity
• Fitter, A & Hay, R Environmental physiology of plants 3rd edition Sept 2001 Harcourt Publishers, Academic Press ISBN 0-12-257766-3
• Lambers, H., Chapin, F.S. III and Pons, T.L. 1998. Plant Physiological Ecology. Springer-Verlag, New York. ISBN 0-387-98326-0
• Lawlor, D.W. (2000) Photosynthesis BIOS ISBN 1-85996-157-6
• Matthews, R. E. F. Fundamentals of plant virology Academic Press,1992.
• Mauseth, J.D.: Botany : an introduction to plant biology. Jones and Bartlett Publishers, ISBN 0-7637-2134-4, A first year undergraduate level textbook
• Morton, A.G. (1981). History of Botanical Science.Academic Press, London. ISBN 0-12-508380-7 (hardback) ISBN 0-12-508382-3 (paperback)
• Raven, P.H, Evert R.H and Eichhorn, S.E: Biology of Plants, Freeman. ISBN 1-57259-041-6, A first year undergraduate level textbook
• Richards, P. W. (1996). The tropical rainforest. 2nd ed. C.U.P. (Pbk) ISBN 0-521-42194-2 £32.50
• Ridge, I. (2002) Plants Oxford University Press ISBN 0-19-925548-2
• Salisbury, FB and Ross, CW: Plant physiology Wadsworth publishing company ISBN 0-534-15162-0
• Stace, C. A. A new flora of the British Isles. 2nd ed. C.U.P.,1997. ISBN 0-521-58935-5
• Strange, R. L. Introduction to plant pathology. Wiley-VCH, 2003. ISBN 0-470-84973-8
• Taiz, L. & Zeiger, E. (1998). Plant physiology. 3rd ed. August 2002 Sinauer Associates. ISBN 0-87893-823-0
• Walter, H. (1985). Vegetation of the earth. 3rd rev. ed. Springer.
• Willis, K (2002) The evolution of plants Oxford University Press ISBN 0-19-850065-3 £22-99

External links

• Hunt Institute for Botanical Documentation
• plant growth and the plant cell from Kimball's Biology Pages
• Botanical Society of America: What is Botany?
• Science and Plants for Schools
• Teaching Documents about Botany Teaching documents, lecture notes and tutorials online: an annotated link directory.
• American society of plant biologists APSB
• Why study Plants? Department of Plant Sciences, University of Cambridge
• Botany Photo of the Day

Flora and other plant catalogs or databases

• The Virtual Library of Botany
• High quality pictures of plants and information about them from Catholic University of Leuven
• Curtis's Botanical Magazine, 1790-1856
• The Trees Of Great Britain and Ireland, by Henry John Elwes & Augustine Henry, 1906-1913
• Botanik-Datenbank (ger.)
• Plant Directory (ger.)
• USDA plant database
• The Linnean Society of London
• Native Plant Information Network