BOTANY,Degrre 2(H. ),Paper 03,group B;BENTHAM AND HOOKER SYSTEM OF CLASSIFICATION,Dr.Dilip Kumar Jha, (lecture series No. 08).

Among all the natural system of classification,the system jointly proposed by George Bentham (1800_1884) and Sir Joseph Dalton Hooker (1817_1911) has gained much popularity. Both of them were working in Royal Botanical Garden,Kew,England. They jointly published their natural system in three volume of Genera Plantarum (1862_1883) In which all the genera of seed plants known upto that time,were described and classified on the basis of all available natural characters or affinities. In their classification they described 97205 species of 7569 genera belonging to 202 families of Angiosperm under 40 orders and 15 series. This system is based on that of A.P.deCandole but its text differs from latter system.

Important Features of the System:

1. This was the last natural system and was not affected by concept of evolution,although it was proposed after publication of Darwin’s theory of evolution. 2. They have placed Gymnosperm between two groups (Dicot and Monocot ) of Angiosperm. 3. They have replaced the term order and family by Cohorts and Natural Orders respectively. 4. In their system,every genus was studied anew;the materials were made available from the British and continental herbaria.

OUTLINE OF THE CLASSIFICATION

Kingdom:PLANTAE Subkingdom: 1.CRYPTOGAMIA Subkingdom: 2.PHANEROGAMIA or SPERMATOPHYTA.

Cryptogamia includes all the flower less plants whereas Spermatophyta includes all the flowering plants which bear seed.

Subkingdom Phanerogamia has been divided into one Groups/Divisions:

1.DICOTYLEDONAE 2.GYMNOSPERMAE 3.MONOCOTYLEDONAE

All the groups have been further divided into Classes,classes into series ,series into Cohorts and cohorts into Natural orders.

Group:DICOTYLEDONAE :03 Classes 1.Polypetalae 2.Gamopetalae 3Monochlamydeae

Polypetalae:03series: 1.Thalamiflorae 2.Disciflorae 3.Calyciflorae Gamopetalae:03 series: 1.Inferae 2.Heteromerae 3.Bicarpellatae Monochlamydae:08 series 1.curvembryeae 2.Multiovulatae aquatica 3.Multiovulatae terrestrial 4.Microembryeae 5.Daphnales 6.Achlamydosporae 7.Unisexuales 8.Ordine anomalie

Group: MONOCOTYLEDONAE has been directly divided into 07 series:

1.Microspermae

2.Epigynae

3.Apocarpae

4.Coronarieae

5.Calycinae

6.Nudiflorae

7.Glumaceae

Merits and demerits of Bentham and Hooker's System:

A.Merits:

1.A great natural system of it’s own kind.

2.Highly suitable for all practical purposes.

3.Monocots have been derived from Dicots.In this system dicots begin with Ranunculaceae and end in Lamiaceae,while Monocots start with Hydrochariaceae and end in Poaceae.

4.Widely accepted in Britain and its commonwealth countries including India.

5.Most of the herbaria are arranged according to this system of classification. 6.Every material was studied by them as new material .Further ,complete description of each plant has been given.

B.Demerits:

1.This is not at all phylogenetic system thus, closely related members are widely separated.

2.Gymnosperm has been placed between Dicots and Monocots.pĺ

3.Dicotyledons have been divided into class,series, cohorts and natural orders whereas monocots have been directly divided into series.

4.Monochlamydeae have been grouped far apart from Polypetalae.

5.In Polypetalae plants with superior ovary have been treated first whereas in Gamopetalae plants with inferior ovary have been treated first.

6.Family Cucurbitaceae is mostly having gamopetalous condition ,but has been placed in Polypetalae.

7.Musaceae and Orchidaceae having several advnced features have been placed in the beginning.

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