Write a brief account of Bentham and Hooker's classification and discuss its demerits.

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Bentham and Hooker's natural classification, published in Genera Plantarum (1862 to 1883), divides seed plants into Dicotyledons, Gymnospermae and Monocotyledons, covering 202 orders. Its demerits include not being phylogenetic, placing gymnosperms between dicots and monocots, the artificial Monochlamydeae and ignoring anatomy and chemistry.

**Introduction**

Bentham and Hooker's classification is a natural system of seed plants published by George Bentham and Joseph Dalton Hooker in ==Genera Plantarum== (1862 to 1883), based on their study of specimens at Kew. It is followed in Hooker's Flora of British India and Gamble's Flora of the Presidency of Madras, which covers present-day ==Andhra Pradesh==, and remains standard in Indian herbaria.

**Outline of the System**

1. **Basis and scope**: Plants are grouped on many characters taken together, mainly floral ones; it covers seed plants only, with about 202 natural orders (families), 7,569 genera and 97,205 species.
2. **Classes**: Seed plants are divided into ==Dicotyledons==, ==Gymnospermae== and ==Monocotyledons==.
3. **Dicotyledons**: Three sub-classes: Polypetalae (Thalamiflorae, Disciflorae, Calyciflorae), Gamopetalae (Inferae, Heteromerae, Bicarpellatae) and Monochlamydeae (eight series).
4. **Gymnosperms and monocots**: Gymnospermae has three orders (Gnetaceae, Coniferae, Cycadaceae); Monocotyledons has seven series from Microspermae (orchids) to Glumaceae (grasses).

**Merits**

1. **Practical**: Based on actual specimens, it is accurate and easy for identification.
2. **Natural**: Related families are largely kept together, and Ranales is rightly placed first among dicots.

**Demerits**

1. **Not phylogenetic**: It does not show evolutionary relationships, though published after Darwin.
2. **Gymnosperms misplaced**: They are placed between dicots and monocots, although they are a separate, more primitive group.
3. **Artificial Monochlamydeae**: Unrelated families are grouped only for lacking petals, separating related families such as Euphorbiaceae from their relatives.
4. **Misplaced orchids**: The advanced Orchidaceae is placed at the start of monocots, before the more primitive Liliaceae.
5. **Narrow evidence**: It ignores anatomy, embryology, cytology and chemistry, and excludes cryptogams.

**Way Forward**

Herbaria can keep the arrangement for convenience while recording modern APG names, and digitising floras and training taxonomists in Andhra Pradesh will link classical and molecular classification.

**Conclusion**

Bentham and Hooker's system gave botany a practical natural classification still used in Indian floras. Its lack of an evolutionary basis and misplaced groups led to phylogenetic systems, but it remains valuable for teaching and identification.

Write a brief account of Bentham and Hooker's classification and discuss its demerits.

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