stigma
Definition
The stigma is the top part of the pistil, which is the female reproductive organ of a flower. It is a sticky, feathery structure that is designed to catch pollen grains. When a pollen grain lands on the stigma, it germinates and grows a pollen tube. The pollen tube travels down the style, which is the long, slender stalk that connects the stigma to the ovary. The pollen tube then fertilises the ovules in the ovary, which eventually develop into seeds.
The stigma is an important part of the plant's reproductive system. It helps to ensure that the pollen grains are successfully transferred to the ovules, so that seeds can be produced.
How can the word be used?
The stigma of the flower is located at the top of the pistil.
Different forms of the word
Noun: stigma (plural: stigmata).
Adjective: stigmatize.
Verb: to stigmatize.
Etymology
The word "stigma" comes from the Greek word "στίγμα", which means "mark" or "brand". It was first used in English in the 16th century.
The word "stigmatize" means "to mark with a stigma" or "to brand with shame".
Question
What does the stigma of the flower do?
AQA Science Exam Question and Answer
Question:
Explain the role of the stigma in the process of pollination in flowering plants. Discuss how its structure and characteristics facilitate successful pollen reception and transfer.
Answer:
The stigma is a crucial component of the female reproductive organ, or pistil, in flowering plants. Its primary role is to facilitate the process of pollination by receiving pollen grains and enabling their germination.
The stigma's structure and characteristics are well-suited for effective pollen reception and transfer. It is often located at the top of the pistil, positioned to come into direct contact with pollen carried by wind, insects, or other pollinators. The stigma's surface is often sticky or covered with microscopic hairs, which enhance its ability to capture and hold onto pollen.
Furthermore, the stigma's anatomical features, such as its specialised cells, provide a suitable environment for pollen germination. Once pollen lands on the stigma, it hydrates and begins to develop a pollen tube, which grows down through the style to reach the ovary, where fertilisation occurs.
The stigma's specific adaptations have evolved to promote successful pollination and increase the likelihood of fertilization, a critical step in plant reproduction. Its ability to interact with pollen from various sources and foster the growth of pollen tubes underscores its pivotal role in the reproductive strategies of flowering plants.