TRENDS IN SYSTEMATIC BOTANY
51
markers, and so on, but these two systems of classification can and
should exist side by side.
From the utilitarian point of view the retention of the taxonomic concept of species is extremely important, for its replacement by a new
category on a different basis would play havoc over a big segment of
biological literature. A warning has been issued, however, against its
continued employment as a basic evolutionary unit. Some evolutionists
would say that this role is filled instead by the breeding population (a
term without taxonomic utility), which is "the effective evolutionary
reality, for it and only it can effect change of adaptedness in sexual organisms" (Epling and Catlin, 1950). From this point of view the species,
and for that matter subspecies, ecotypes, and other units above the level
of the local population, can be looked upon as proofs of evolutionary
activity which was begun far below the specific level.
An extensive summary of the principles and dynamics of evolution in
the plant world, particularly as seen from the taxonomic point of view,
has been presented by Stebbins (1950). Such topics as patterns of
variation, mutations, natural selection, genetic systems, isolating mechanisms, speciation, polyploidy, and apomixis, as treated here, stress the
fundamental importance of taxonomic data in experimental studies of
this nature.
II. TAXONOMY AND CLASSIFICATION
Classification of plants was the first form in which the science of
botany developed. From the dawn of botanical knowledge and the Age
of the Greek Philosophers down to the time of Linnaeus, the history of
botany is essentially the history of systematic botany, or plant classification. The creation of a system that enables one to identify correctly the
kinds of organisms and to classify the multitudinous forms in nature
into easily recognized groups based on relationship has always been an
indispensable forerunner to other kinds of botanical studies, and by its
very nature it must continue to be basic. Correct names for plants are
essential before reporting any other kinds of facts about them.
When one becomes interested in the classification of plants he hears
the terms "taxonomy," "systematic botany," "biosystematics," "experimental taxonomy," and perhaps others used to describe this science. He
at once detects that they are variously applied in the literature, often as
synonyms of one another. A sound clarification of these terms is given
by Mason (1950). He would define taxonomy in an inclusive sense as
did the elder de Candolle, who introduced the term and applied it
through usage as a synthesis of facts into an expression of botanical
51
markers, and so on, but these two systems of classification can and
should exist side by side.
From the utilitarian point of view the retention of the taxonomic concept of species is extremely important, for its replacement by a new
category on a different basis would play havoc over a big segment of
biological literature. A warning has been issued, however, against its
continued employment as a basic evolutionary unit. Some evolutionists
would say that this role is filled instead by the breeding population (a
term without taxonomic utility), which is "the effective evolutionary
reality, for it and only it can effect change of adaptedness in sexual organisms" (Epling and Catlin, 1950). From this point of view the species,
and for that matter subspecies, ecotypes, and other units above the level
of the local population, can be looked upon as proofs of evolutionary
activity which was begun far below the specific level.
An extensive summary of the principles and dynamics of evolution in
the plant world, particularly as seen from the taxonomic point of view,
has been presented by Stebbins (1950). Such topics as patterns of
variation, mutations, natural selection, genetic systems, isolating mechanisms, speciation, polyploidy, and apomixis, as treated here, stress the
fundamental importance of taxonomic data in experimental studies of
this nature.
II. TAXONOMY AND CLASSIFICATION
Classification of plants was the first form in which the science of
botany developed. From the dawn of botanical knowledge and the Age
of the Greek Philosophers down to the time of Linnaeus, the history of
botany is essentially the history of systematic botany, or plant classification. The creation of a system that enables one to identify correctly the
kinds of organisms and to classify the multitudinous forms in nature
into easily recognized groups based on relationship has always been an
indispensable forerunner to other kinds of botanical studies, and by its
very nature it must continue to be basic. Correct names for plants are
essential before reporting any other kinds of facts about them.
When one becomes interested in the classification of plants he hears
the terms "taxonomy," "systematic botany," "biosystematics," "experimental taxonomy," and perhaps others used to describe this science. He
at once detects that they are variously applied in the literature, often as
synonyms of one another. A sound clarification of these terms is given
by Mason (1950). He would define taxonomy in an inclusive sense as
did the elder de Candolle, who introduced the term and applied it
through usage as a synthesis of facts into an expression of botanical