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Q. Describe the various types of placentations found in flowering plants.
Answer:
Explanation:
The formation, type, structure or arrangement of the placenta is referred to as placentation. Placentation transfers nutrients, respiratory gases and water from maternal tissue to a growing embryo, as well as removes waste from the embryo in some cases. Placentation is most commonly associated with live-bearing mammals, but it also occurs in a variety of fish, reptiles, amphibians, invertebrates and flowering plants. Placentas have evolved more than 100 times in vertebrates, with squamate reptiles accounting for the majority of these instances.
Placentation is the attachment of ovules inside the ovary in flowering plants.
Funiculi, the plant equivalent of an umbilical cord, connect the ovules inside a flower’s ovary (which later become the seeds inside a fruit). The section of The placenta is the portion of the ovary where the funiculus attaches.
The arrangement of ovules inside the ovary is referred to as placentation. It is divided into five categories:
(A) Placentation in the margins
Marginal placentation refers to an ovary in which the placenta forms a ridge along the ventral suture of the ovary and the ovules develop in two rows. Peas are known for having this type of placentation.
(B) Placentation in the parietal lobe
The ovary is said to have parietal placentation when the ovules develop on the inner walls of the ovary.
- C) Placentation at the axile
The placenta is axial and ovules are attached to it in axile placentation. China rose, lemon and tomato are just a few examples.
(D) Placentation at the base-
Basal placentation refers to an ovary in which the placenta develops from the base and a single ovule is found attached to the base. Marigold and sunflower contain it.
(E) Placentation in the center of the uterus
The ovules develop on the central axis in free central placentation, and the septa are absent. Dianthus and primrose have this type of placentation.
