Palynology is the scientific study of pollen, spores, and other microscopic organic-walled structures produced by plants, fungi, and certain microorganisms. This field encompasses both living and fossilized forms of these materials, collectively referred to as palynomorphs. The term “palynology” is derived from the Greek words for “strew” or “sprinkle,” reflecting the nature of these tiny particles.
Use of Palynology in Plant Taxonomic study
Pollen grains and spores possess unique morphological characteristics, such as size, shape, and surface ornamentation, which can be used to identify specific plant species. Palynologists examine these microscopic structures to differentiate between closely related plants, aiding in the classification process.
Taxonomic Markers
Pollen morphology, including size, shape, aperture type, and exine ornamentation, serves as taxonomic markers that help in grouping plants into families, genera, and species. These unique characteristics are used by palynologists to differentiate between different plants and contribute to the overall taxonomy of plants.
Segregation of Plant Families
Palynological evidence can be used to segregate plant families into two groups:
Stenopalynous: Taxa of the family display more or less the same type of pollen grains, e.g., Poaceae, Chenopodiaceae, Amaranthaceae.
Eurypalynous: Taxa of the family show obvious differences in pollen types, e.g., Asteraceae, Rubiaceae, Acanthaceae, Verbenaceae, Solanaceae, Convolvulaceae, Fabaceae.
Delimitation at Family and Genus Level
Palynological characters have been used to separate families and genera:
– Fumariaceae is separated from Papavaraceae, and Nelumbonaceae from Nymphaeaceae based on pollen characters.
– Malvaceae and Bombacaceae are distinguished based on exine characters, with Malvaceae showing spinous exine and Bombacaceae showing reticulate exine in pollen grains.
– The genus Populus in Salicaceae has spherical pollen grains without a distinct aperture, while Salix has long, narrowed, 3-furrowed pollen grains.
Differentiation at Species Level
Pollen characteristics can also help differentiate species within a single genus:
- Germinal aperture is used to distinguish different species of Anemone.
- Exine pattern is used to differentiate species of Bauhinia (Fabaceae).
- Pollen size plays a vital role in demarcating different species of Malva (Malvaceae).
Palynological evidence, including pollen morphology, aperture type, and exine ornamentation, provides valuable taxonomic markers that assist in the classification and identification of plants at various taxonomic levels, from family to species.