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A Handbook of Biology
In plantae 5 groups are included – Algae, Bryophytes, Pteridophytes,
Gymnosperms and Angiosperms.
It includes all eukaryotic chlorophyll-containing organisms commonly
called plants.
A few members are partially heterotrophic such as insectivorous plants
or parasites. Bladderwort and venus fly trap are example of insectivorous
plants and Cuscuta is a parasite.
Life cycle of plants has two distinct phases – the diploid sporophytic and
the haploid gametophytic – that alternate with each other.
SÝSTËM ØF BÏØLØGÏÇÅL ÇLÅSSÏFÏÇÅTÏØÑ
1
2
ÑÅTÜRÅL ÇLÅSSÏFÏÇÅTÏØÑ SÝSTËMS
These are based on natural affinities among organisms. E.g.
Classification for flowering plants given by George Bentham
and Joseph Dalton Hooker.
ÅRTÏFÏÇÏÅL ÇLÅSSÏFÏÇÅTÏØÑ SÝSTËMS
These are based on the external features : E.g.,
Linnaeus’s artificial system of classification was based
on the androecium structure.
It is the earliest classification system used only gross
superficial morphological characters including colour,
number habit and shape of leaves etc.
Aristotle was the earliest to attempt a more scientific
basis for classification.
Aristotle used simple morphological characters to
classify plants into trees, shrubs and herbs.
Aristotle divided animals into two groups, those
which had red blood (Enaima) and those that did not
(Anaima).
Aristotle is called father of Zoology, father of Biology
and father of Embryology.
PHÝLØGËÑËTÏÇ ÇLÅSSÏFÏÇÅTÏØÑ SÝSTËMS
These are based on the evolutionary relationships.
Numerical taxonomy:
It is based on all observable characteristics. It is easily carried out using
computers. Number & codes are assigned to all the characters and the
data are processed. Thus, hundreds of characters can be considered
giving equal importance.