Palynology is the branch of science that studies pollen grains, spores, and other microscopic plant structures called palynomorphs. It involves the study of the formation and development of pollen grains, as well as their structure, composition, and physical characteristics. Palynology plays a crucial role in various fields, including plant embryology, palaeobotany, and pharmacognosy.

1. Plant embryology:
Plant embryology is the study of the development and formation of embryos in plants. It encompasses the processes involved in the fertilization, embryogenesis, and maturation of seeds. Pollen grains play a vital role in plant embryology as they are the male gametophytes responsible for fertilizing the female reproductive structures of plants. The study of pollen grains and their development helps in understanding the reproductive processes and embryogenesis in plants.

2. Palaeobotany:
Palaeobotany is the branch of paleontology that deals with the study of ancient plant fossils. Pollen grains are among the most common and well-preserved plant fossils found in sedimentary rocks. By studying the morphology, structure, and composition of pollen grains, palaeobotanists can determine the identity, distribution, and evolution of plant species in the past. Palynology provides valuable insights into the paleoecology, paleoclimatology, and evolution of plants throughout geological time.

3. Pharmacognosy:
Pharmacognosy is the branch of pharmacy that deals with the study of medicinal drugs derived from natural sources, including plants. Pollen grains contain various bioactive compounds such as flavonoids, alkaloids, and phenolic compounds, which have medicinal properties. The study of pollen grains in pharmacognosy helps in identifying and characterizing these bioactive compounds, which can be used in the development of new drugs or herbal medicines. Additionally, pollen analysis can be used to authenticate the quality and purity of herbal products.

In conclusion, the study of pollen grains falls under the field of palynology, which encompasses various disciplines such as plant embryology, palaeobotany, and pharmacognosy. Palynology provides important insights into plant reproduction, evolution, paleoecology, and the development of medicinal drugs from natural sources.

It is palynology as that's what NCERT says..