Systematics

Systematics is the study of biological diversity and the organisation of the data into a classification. The word systematics is derived from the Latin word ‘systema,’ which refers to the orderly organisation of organisms. It encompasses the species’ evolutionary relationships. Plant systematics is the study of how plants and their evolutionary descent interact. 

Similarities, proximity, and connections between organisms are used to classify them. It depicts the evolutionary link and history of ancestry between various organisms. Individual similarities suggest that they may have shared a common ancestor. It depicts the present living creatures’ evolutionary route. A group is made up of closely related species that share a gene pool.

Taxonomy

The word “taxonomy” comes from two Greek words: “taxis” which means “arrangement” and “nomos” which means “rules.” Plant taxonomy is the science of classifying plants as per a set of standards. A. P. de Candolle, a Swiss botanist, created the term taxonomy in his work “Théorie élémentaire de la botanique.”

Plant taxonomy is a field of botany that involves characterising, identifying, classifying, and nomenclature plants based on their similarities and variations.

The following are the objectives of plant taxonomy:

Identification

It is the process of determining the unknown species’ traits and comparing them to those of recognised species.

Characterisation

It is the process of describing all the features of a newly discovered species.

Classification

It is the process of grouping and organising known species into various groups or taxa based on their similarities and variations.

Nomenclature

It is the process of assigning a scientific name based on a set of rules.

Organisms are classified into taxonomic groups based on their similarities and distinguishing characteristics. The following are the several taxonomic categories in their hierarchical order: Kingdom, Phylum, Class, Order, Family, Genus and Species. As one progresses from species to the kingdom, the proportion of shared traits diminishes, as species have basic commonalities and organisms in the very same kingdom share the fewest qualities.

List of Plant Taxonomy Systems

Only a few vegetative features were considered in the first categorisation scheme. Along with morphological aspects, modern taxonomy investigations have become more comprehensive, taking into account numerous morphological, cellular, and molecular factors, such as cellular and reproductive properties, method of feeding, environment, evolutionary connections, and so on.

The following is a list of plant taxonomic systems:

Artificial systems

The early systems that sought to classify organisms based on only a few superficial characteristics were artificial systems. Because this was a special effort to organise live species, it was significant in the history of biological taxonomy. However, it did not consider morphological characteristics or evolutionary relationships and assigned vegetative and sexual qualities equal weight. The environment has a significant impact on vegetative characteristics, leading to the species that were closely associated with being held separately.

1. 1. Aristotle categorised plants into herb, shrub, and tree categories based on basic physical characteristics over 2000 years ago.
   2. Theophrastus sought to categorise plants in his work “Historia Plantarum or Enquiry into Plants” based on how they reproduced and what they were used for. He is known as the “Father of Botany.”
   3. Carl Linnaeus is widely regarded as the “Father of Modern Taxonomy.” In his work “Systema Naturae” (1735), he defined the plant kingdom, animal kingdom, and mineral kingdom as a hierarchical categorisation system for the natural world. He recognised the value of floral characteristics and categorised plants according to the number of stamens they contained. It is also referred to as the sexual categorisation system.
   4. Linnaeus continued to add new works to his collection. He briefly detailed all the species he knew in “Species Plantarum”. It has roughly 7,300 plant species. Depending on the structure, union, length, and the number of stamens, he separated the plant kingdom into 24 groups.
   5. Linnaeus was the one who came up with the Binomial nomenclature system. He had set standards for naming every species in “Philosophia Botanica.” It is called binomial because each name includes a genus name and a species name, such as Solanum tuberosum (potato).

Natural systems

More characteristics were evaluated for categorising in this classification system. It was founded on the organisms’ inherent vegetative and floral commonalities. It looked into the anatomy of a cell, different types of embryos, and phytochemistry, among other things.

1. Bentham and Hooker created the most valuable natural system of flowering plant categorisation. Plants were divided into two groups: Cryptogams- non-flowering plants and Phanerogams- flowering plants.
2. Phylogenetic systems: This system was created after Darwin’s theory of evolution was published. According to this approach, all creatures belonging to the same taxon descended from a common ancestor. This approach is used to classify organisms based on evolutionary sequences and genetic links. Genetic factors were also investigated apart from the physical traits documented in fossil records. Biologists have extensively recognized it all around the world. 

The following are the two most crucial phylogenetic classification systems:

1. Engler and Prantl classification system: Floral features such as a single whorl or no perianth, as well as unisexual flowers pollinated by wind, were regarded primitive in comparison to two whorls, the perianth, and bisexual blooms pollinated by insects in this sort of system. They divided the plants into 13 divisions based on the increasing intricacy of the floral morphology.
2. Hutchinson’s classification: Hutchinson divided angiosperms into monocotyledons and dicotyledons in his classification. It is a part of angiosperm systematics.
   1. Dicotyledons have been further categorized into two:
      1. Lignosae– woody plants.
      2. Herbacea– herbaceous plants.
   2. Monocots were separated into three groups based on flower form:
      1. Calyciferae– calyx present.
      2. Corolliferae– petaloid perianth
      3. Glumiflorae– perianth absent.

Modern Taxonomic Advancements

Many technologies for identifying genomic information have been discovered since the emergence of molecular biology. It has given us the ability to evaluate organisms at different taxonomic levels and answer classification problems.

Molecular systematics in taxonomy

 It is the science of classifying organisms based on differences in protein and DNA to generate detailed taxonomic categorizations that are not entirely based on appearance.

Numerical taxonomy

This is done with the use of computers, and all apparent traits are taken into account. It is also sometimes referred to as numerical systematics. A code and a number are allocated to each trait. Hundreds of characters can be examined simultaneously and assigned equal weight.

Cytotaxonomy

It is the study of taxonomy using cytological data such as chromosome number, size, shape, and so on.

Chemotaxonomy

It is the study of taxonomic relationships using chemical elements of plants. Chemotaxonomy studies proteins, amino acids, nucleic acids, amino acids, pe