Bentham And Hooker Classification
George Bentham (1800-1884) and Joseph Dalton Hooker (1817-1911), British botanists linked to the Royal Botanic Gardens in Kew, England, collaborated on a significant work, Genera Plantarum (1862-1883) in 3 Vols. This monumental taxonomic effort, spanning a quarter-century, described all known seed plant genera at the time. It served as a guiding influence for Kew botanists for generations. Published between July 1862 and April 1883, the work presented top-tier descriptions of seed plant families and genera.
1.0Classification of Bentham and Hooker
Bentham and Hooker's "Genera Plantarum" classified seed plants, detailing 202 families and 7,569 genera, estimating a total of 97,205 species. Their system refined earlier classifications by de Candolle and Lindley, building on de Jussieu's work.
It emphasized natural affinities, predating Darwinian concepts. The classification, rooted in personal specimen studies rather than mere compilation, gained popularity and authenticity. Major herbaria worldwide adopted this system.
Seed plants (phanerogams) were categorized into three classes: Dicotyledons, Gymnospermae, and Monocotyledons. Dicotyledons were further divided into Polypetalae, Gamopetalae, and Monochlamydeae based on petal presence and fusion.
These subclasses were then subdivided into series, orders (cohorts), and families (natural orders). Monochlamydeae and Monocotyledons had no recognized orders; their series directly led to families.
2.0Merits of this classification
- The system is highly practical for plant identification, especially for routine use.
- Based on careful examination of living seed plant specimens, not just compiled facts.
- The gymnosperms are placed as a separate independent group and not along with dicots as
- had been done by de Candolle.
- Dicotyledons are positioned before Monocotyledons, a widely accepted order.
- Dicots start with Ranales which is considered as most primitive amongst the angiosperms by
- many taxonomists.
- The system provides accurate descriptions of families and genera, along with helpful identification keys. The inclusion of subgenera for larger genera enhances the ease of identification.
- Arrangement based on natural affinities determined by easily observable morphological features.
- The position of gamopetalae after polypetalae is accepted as fused petals are considered an advanced character over free petals.
- The sequence adopted in the classification suggests an evolutionary pattern.
3.0Demerits of this classification
- The system, despite being published after Darwin's evolutionary theory, does not integrate phylogeny into its classification.
- The position of gymnosperms between dicots and monocots is inappropriate according to the accepted evolutionary sequence.
- The grouping of families is artificial as it is based on a single character and has separated some closely related families.
- The arrangement of Monocots is unnatural and unphylogenetic.
- The system categorizes angiosperms into dicotyledons and monocotyledons. In contrast, modern phylogenetic systems position paleoherb families and Magnoliids ahead of monocotyledons and Eudicots.