# DNA Barcoding as a Plant Identification Method
## 1 Introduction  
_\"Taxonomy (the science of classification) is often undervalued as a glorified form of filling-with each species in its folder, like a stamp in its prescribed place in an album; but taxonomy is a fundamental and dynamic science, dedicated to exploring the causes of relationships and similarities among organisms. Classifications are theories about the basis of natural order, not dull catalogues compiled only to avoid chaos\", as the famous paleontologist, evolutionary biologist, and historian of science [PERSON] says._  
Biological diversity, commonly referred to as biodiversity, encompasses the variety present within and between species, as well as across ecosystems. At its core, the species serves as the fundamental unit of biodiversity, and the richness of intra-specific genetic variation forms the bedrock upon which biodiversity is built. In essence, biodiversity captures the intricate tapestry of life, accounting for the differences among species and the genetic diversity within each, ultimately contributing to the resilience and adaptability of ecosystems [1]. According to data collected from the International Union for Conservation of Nature (IUCN) Red List for 2022, more than 420,000 plant species exist around the world, yet a subset of them can be identified by traditional taxonomy [2] based on morphological structures, namely, on the phenotypic characteristics of individual organisms. The conventional taxonomy system faces inherent limitations, particularly in its dependence on morphological criteria. Vegetative characteristics, susceptible to environmental influences, introduce variability and ambiguity into the identification process. Compounded by the existence of cryptic plant species--morphologically identical yet representing distinct evolutionary lineages--traditional taxonomy methods prove inadequate for precise plant identification. The challenges posed by these limitations underscore the necessity for integrating molecular techniques, like DNA barcoding, to overcome these shortcomings. By incorporating genetic data, we can achieve more accurate and reliable plant classification, addressing the inherent constraints of relying solely on morphological traits [3,4]. In the past 20 years, a novel approach based on the use of DNA markers has been developed. DNA barcoding provides a reliable and rapid method for the identification of organisms [5,6]. As DNA is not affected by external or other environmental factors, it is stable and can be found in all tissues, and thus, this method can be very useful [7]. The term \"DNA barcode\" was first introduced by [PERSON] of the University of Guelph in 2003 [8]. DNA barcodes are standardized sequences of DNA, ideally unique, from the genome either of the organism or from its organelles, with a length between 400 and 800 base pairs, that is used to identify/classify an organismal group following amplification, sequencing, and comparison with a reference database containing the relevant sequences from different species [8]. By combining the strengths of two molecular biology methods, PCR amplification and sequencing, DNA barcoding offers a quick and accurate approach to identify different groups. Interestingly, at the species level, DNA barcoding can be used to characterize novel, unknown species, or cryptic species [9], two or more species that are classified as a single, as they are superficially morphologically similar and hence cannot be identified using classical taxonomy [10,11]. Notably, the highest cryptic diversity so far has been found in animals, particularly in invertebrates [9,12,13,14]. DNA barcoding can also be used for the preservation of rare endemic and endangered species [15] and, in general, for the research of evolution, ecology, and conservation of plants, especially since biodiversity has been threatened by anthropogenic activity, pollution, deforestation, and resource extraction [6,9].