HERBARIUM SPECIMENS

Herbarium Specimens



HERBARIUM SPECIMENS

For the purpose and aim to understand and comprehend the accounts of biological research, we shall be discussing specimens coming from a herbarium. A herbarium implies an area or a platform where individuals keep, maintain and preserve different varieties of plant that may have existed or seize to exist in today's modern world.

Herbaria are essential for the study of plant taxonomy, the study of geographic distributions, and the stabilizing of nomenclature. Thus it is desirable to include in a specimen as much of the plant as possible (e.g., flowers, stems, leaves, seed, and fruit). As the world faces a burgeoning human population and changing climate, the sustainability of its food resources are of key importance. Humans rely on an extremely narrow range of food plants: three species of cereals (maize, rice, wheat) make up approximately 50 percent of the world's calorific consumption. Plant breeding practices since the 1950s have reduced the genetic diversity of crop plants in western agriculture to a drastic level.

The preservation of the remaining genetic diversity in crop plants, and its conservation and management, are core goals of the coming decades. Phylogeography, the mapping of geographical and temporal patterns in genetic diversity, is an important tool in this process. Phylogeography can help us explore the processes that affected crop biodiversity in the past, e.g., where and when a crop was domesticated, how many times it was domesticated, what were the initial routes of spread of its cultivation and the effects of subsequent prehistoric and historic processes (Berg, 2009).

The role of herbarium specimens

Crop landraces represent a uniquely valuable source of biodiversity. However, even phylogeographic analyses of crop landraces have major limitations. In many regions landraces were not collected prior to their replacement by modern varieties (early 20th century onwards). The disappearance of landraces from these areas (e.g., Central Europe) was neither noticed nor considered important, and therefore many geographic regions are not represented in germplasm banks. Our previous research has shown that the distribution of extant cereal landraces in Europe, for example (largely found in seed banks, with a smaller number still grown in situ), is patchy, especially in central and northern Europe. Extant European barley landraces are largely confined to regions of rugged upland topography, such as the Alpine forelands and the Apennine spine of Italy.

Landraces may no longer be present in certain areas because of environmental change or differing patterns of land use, or they were never collected in the first place from certain regions because of inaccessibility or political instabilities, etc. Moreover, inferring the respective contributions of different cultural episodes in the past to contemporary landrace biogeography is not a straightforward matter. The inclusion of historic herbarium specimens is able to address both of these limitations, since such specimens can fill in gaps where modern landraces. are no longer grown nor represented in germplasm banks. An example of the use of historic material in a crop phylogeographic study is provided by the analysis of a photoperiod response gene, ...