Historical prospective of Plant Classification
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Taxonomy is the science that explores, describes, names, and classifies
all organisms.
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Angiosperms of about 300,000 species of flowering plants is the largest and most diverse group within the kingdom Plantae. Angiosperms represent approximately 80
percent of all the known green plants now living.
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The development of
angiosperm classification has been one of the most fascinating subject.
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A study of sequential
events led to various classifications from time to time by several eminent
scholars, botanists and thinkers. Plants have been known from times immemorial
and remained intimately associated with human life.
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As the number of plants
known to men increased, the necessity to organize them was felt and perhaps
earliest classification came into existence.
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The knowledge of
morphology, embryology, palynology, cytology, biochemistry, physiology, and
phylogeny have added steps to the concept of classification.
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The history of plant taxonomy include the emergence of the concept of
natural classification, the adoption of the binomial naming system (with the
major role of Linnaeus) and other universal rules for the naming of plants, the
formulation of the principle of subordination of characters, and the advent of
the evolutionary thought.
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More recently, the cladistic theory (initiated by Hennig) and the
rapid advances in DNA technologies allowed to infer phylogenies and to propose
true natural, genealogy-based classifications. In a second part, we put the
emphasis on the challenges that plant taxonomy faces nowadays.
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The still very incomplete taxonomic knowledge of the worldwide flora
(the so-called taxonomic impediment) is seriously hampering conservation
efforts that are especially crucial as biodiversity has entered its sixth
extinction crisis. It appears mainly due to insufficient funding, lack of
taxonomic expertise, and lack of communication and coordination.
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Although the taxonomy of the angiosperms is still incompletely
known, the latest classification system incorporates a large body of
comparative data derived from studies of DNA sequences.
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It is known as the Angiosperm Phylogeny Group IV (APG IV) botanical classification system.
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The angiosperms came to be considered a group at the division level
(comparable to the phylum level in animal classification systems) called
Anthophyta, though the APG system recognizes only informal groups above the
level of order.
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Taxonomy had its earliest beginning in writings of Theoprastus and
ancient Greek philosopher Aristotle-Father of botany in his book Historia
plantarum and classified and described about 500 plants.
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In India, in vedic literature several technical terms were used in
description of plants and its parts.
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A rudimentary form of
classification of plants and trees can be found in the Vedas, the oldest
composition by human beings. Historians assign c.1500-600 BC as time for the
composition of the Vedas.
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There are four Vedas viz.
Rigveda, Samveda, Yajurveda, and Atharvaveda.
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All the Vedas mention
about plants and trees. We can clearly find some basis for classification of
plants and trees in Yajurveda and Atharvaveda.
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The Rigveda (1500-1000
BC) mentions about the healing properties of herbs which it call drava which is
present in plants. The Yajurveda and the Atharvaveda (900-600 BC) classified
plants on the basis of morphology.
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The hymns say that
Brihaspati (the God of plants) created various types of plants. The types of
plants according to the hymns are: 1. Apushpa- Non-flowering 2. Pushpini-
Having flower 3. Aphala- Without fruits 4. Phalinirya- Having fruits
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