BOTANY Higher Secondary Second Year - Textbooks Online

and his classification was more important
than others. The main defect of this system
is that totally unrelated plants are brought
together in a single group and those that
are closely related plants are placed in
widely separated groups. For example,
plants belonging to Zingiberaceae of
Monocotyledons and that of
Anacardiaceae of Dicotyledons had been
placed in one group called Monandria,
as these possess only one stamen. Another Fig. 1.1. Carolus Linnaeus
defect of this system was that no
importance was given to either natural or phylogenetic relationships among
different groups of plants.
Natural system
In this system of classification, plants are classified based on their
natural affinities. More number of characters are taken into consideration
in this system. It is mainly based on all the informations that were available
during the time of direct observation of plants. The most important natural
system of classification of seed plants was proposed by two British botanists
George Bentham and Sir Joseph Dalton Hooker. It helps to determine
the relationships between various groups of plants. However, it does not
attempt to bring out evolutionary relationships among different
groups of plants.
Phylogenetic system
This system is based on evolutionary sequence as well as genetic
relationships among different groups of plants. In addition to this, it
employs as many taxonomic characters as possible. Charles Darwin’s
concept of Origin of Species had given enough stimulus for the creation of
phylogenetic system of classification. Adolf Engler (1844-1930) and Karl
Prantl (1849-1893) of Germany published a phylogenetic system in their
monograph on “Die Naturlichen Pflanzen Familien”. In this system, floral
characters such as single whorl of perianth or no perianth and unisexual
flowers pollinated by wind were considered as primitive characters when
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