Which of the following systems of plant classification is a natural system of classification ?

Question

Accepted Answer

The correct option is 4: Bentham and Hooker

The system of classification proposed by George Bentham and Joseph Dalton Hooker is universally considered the most important **Natural System of Classification** for seed plants (Phanerogams). A natural system aims to classify organisms based on the overall, non-evolutionary relationships or natural affinities among them, using as many morphological characters as possible (such as floral, anatomical, and reproductive traits). Their monumental work, *Genera Plantarum*, published between 1862 and 1883, described nearly 100,000 species across 202 families. Although it was a pre-Darwinian system that did not account for evolutionary (phylogenetic) relationships, its detailed descriptions, practical arrangement, and use of actual specimens made it highly accurate and extremely suitable for practical utility in herbaria and botanical gardens, where it is still used today for plant identification.

The incorrect option is 1: Engler and Prantl

The system developed by Adolf Engler and Karl Prantl, published in *Die Natürlichen Pflanzenfamilien*, is categorized as a **Phylogenetic System of Classification**, not a purely natural one. Phylogenetic systems attempt to group organisms according to their evolutionary history and common ancestry. Engler and Prantl's system, one of the earliest phylogenetic approaches, arranged plant groups from simpler to more complex forms, based on the assumption that simpler flower structures (like achlamydeous or apetalous) were more primitive. A major departure from natural systems was their placement of Monocotyledons before Dicotyledons, an arrangement based on a perceived evolutionary sequence rather than overall structural affinity, which is the hallmark of a natural system.

The incorrect option is 2: Hutchinson

John Hutchinson’s classification, detailed in his work *The Families of Flowering Plants*, is also a later, more evolved **Phylogenetic System**. Hutchinson’s system explicitly sought to demonstrate the evolutionary paths of flowering plants, often represented as a phylogenetic tree (a 'Hutchinsonian tree'). His classification was based on several key evolutionary dictums, such as the idea that woody plants are more primitive than herbaceous plants, and free petals are more primitive than fused petals. This strict adherence to presumed evolutionary lines, which often separated groups with close overall natural resemblances, distinguishes it sharply from the non-evolutionary approach of a natural system.

The incorrect option is 3: Rendle

Alfred Barton Rendle's system of classification is primarily an adaptation or modification of the previously mentioned **Phylogenetic Systems**, specifically those proposed by Engler and Prantl. Rendle’s work, *The Classification of Flowering Plants*, maintained the phylogenetic arrangement that was becoming popular in the early 20th century, especially its recognition of the importance of evolutionary relationships. As it is built upon the phylogenetic framework, it is not considered a traditional natural system like that of Bentham and Hooker, which focuses solely on non-evolutionary morphological similarities for grouping. Therefore, like Engler and Prantl, Rendle’s system is positioned on the evolutionary side of taxonomic history.