• Plant kingdom includes eukaryotic, autotrophic or photosynthetic and non-motile organisms.
• They have well defi ned cellulosic cell wall. Plastids are present.
• Plant kingdom includes fi ve major plant groups i.e., Algae, Bryophyta, Pteridophyta, Gymnosperms and Angiosperms as proposed by R.H.Whittaker in 1969.
• In earlier classifi cations kingdom plantae also included fungi and members of protista and monera having cell walls.
TYPES OF CLASSIFICATION
There are various types of classifi cation in angiospermic plants.
1. Artifi cial system of Classifi cation :
• All taxonomists, from Aristotle to Linnaeus, classifi ed organisms on the basis of external observable (morphological) characters like structure of fl oral parts ( number of stamens), root modifi cation, leaf venation etc.
• In this system no weightage was given to natural and phylogenetic relationship. Such system is based on one or a few superfi cial similarities.
• This is an arbitrary system of classification. Linnaeus also used such system of classifi cation
• This system may also be based upon habit and habitats of the organisms.
2. Natural System of Classifi cation :
• It uses more number of characters and is based upon natural affi nities using homology and comparative study.
• Bentham - Hooker used this system of classifi cation for angiosperms.
3. Numerical Taxonomy ( Phenetics ) or Quantitative taxonomy :
• This system uses numerical methods for evaluating the similarities and differences between the species.
• This uses maximum number of characters, without giving extra emphasis on anyone.
• Sophisticated calculating machines and computers are used for statistical analysis. This system gives equal importance and weightage to all the characters used for taxonomy.
• As this system was fi rst attempted by Adanson (1763), the numerical taxonomy is also known as Adansonian system
(The Phenetics is considered to be a better classifi cation as it uses a huge number of comparative features).
4 Phylogenetic Classifi cation (Cladistics) :
• This system of classifi cation is based upon evolutionary relationship and uses morphological characters, origin and evolution of the different organisms.
• The ‘Family tree’ in this system is called Cladogram.
• This system has led to the emergence of new systematics and bio-systematics.
• Phylogenetic system of classifi cation was proposed by Hutchinson.
• Adolf Engler and K. Prantl, both German Botanists, published ‘Phylogenetic system of classifi cation’ in plants and considered monocots to be the more primitive than the dicot angiosperms.
• They published twenty volumes of classifi cation (from algae to angiosperm) in Die Natuerlichen Phlanzenfamilien.
5 Karyotaxonomy :
• This system of classifi cation uses information like chromosome number, structure of chromosomes, size and shape of chromosomes and the behaviour of chromosomes during meiosis.
