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In this article we will discuss about the merits and demerits of Bentham and Hooker’s system.
Merits of Bentham and Hooker’s System:
1. The description of families and genera is very accurate.
2. The system is very handy for identification purposes.
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3. The system is of great practical convenience.
The British and Commonwealth herbaria therefore still adopt this system in arrangement of families.
4. Each family had a synopsis at the beginning which is very useful in identification.
5. The system starts from Ranales, which are now universally considered to be most primitive living angiosperms.
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6. Larger genera subdivided into subgenera and sections.
7. They believed in evolution through reduction and hence placed monocots after dicots; even in dicots, the dichlamydeous polypetalae and gamopetalae were placed before the uniseriate monochlamydeae.
8. The gamopetalae placed after polypetalae is justified since union of petals is considered to be an advanced feature.
9. The polypetalae includes Thalamiflorae and Calyciflorae of de Candolle. But Bentham and Hooker distinguished a new series Disciflorae which includes orders which cannot be assigned to Thalamiflorae or Calyciflorae.
10. The 3 series – Thalamiflorae, Disciflorae and Calyciflorae show gradual evolutionary advance from marked hypogyny to epigyny.
11. Treating Cucurbitaceae and Umballiferae (Apiaceae) at the end of Polypetalae as connecting links between poly- and gamopetalous families.
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12. Creation of Monochlamydeae at the end of Dicots.
13. Disputed families included in Ordines anomali.
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14. Placing of unisexual monocot families after bisexual families e.g. Palmae and Araceae after Liliaceae.
15. The series Glumaceae with extremely reduced flowers and inflorescences, placed at the end of the flowering plants.
16. The system was never conceived by its authors on the basis of phylogeny. The theory of organic evolution (theory of descent) was announced independently by Darwin and Wallace in 1859. So, any criticism of the system on the basis of phylogeny is not too justified.
Demerits of Bentham and Hooker’s System:
1. The system does not give any idea as to the evolutionary history of any genus, family or order.
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2. In this system grouping of plants is mainly based on single and artificial characters; with the result, that closely allied families are placed widely apart.
3. The group “Monochlamydeae” is entirely artificial.
4. Gymnospermae is placed between the Dicotyledones and Monocotyledones, which is extremely anomalous.
5. The system does not show any phylogenetic relationship. The main demerit is that this system does not give us any idea as to the evolutionary history of any genus, family or order nor does it give any idea of phylogenetic relationship between them.
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6. Compositae (Asteraceae) is a highly advanced family and placed in Inferae at the beginning of Gamopetalae.
7. Advanced families like Orchidaceae and Scitamineae are treated in the beginning of monocots.
8. Liliaceae and Amaryllidaceae were kept apart though they are very closely related.
9. The Amaryllidaceae is more allied to Liliaceae but is clubbed with Scitamineae in series Epigynae, on account of inferior gynoecium.
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10. The position of series Apocarpae is unsatisfactory due to its free and superior carpels.
