Question

Free central placentation is found in
(A) Citrus
(B) Dianthus
(C) Argemone
(D) Brassica

Answer 1

Hint: The placentation is the arrangement of the ovules in the placenta and of the placentas in the ovary.

Complete Answer:
- The free central placentation ovules develop on a central column in a compound ovary lacking septa at base only.
- Free Central placentation resembles axile placentation however the column is not connected by partitions to the ovary wall, and thus no locules are formed.
- Ovary is one chambered and the placenta bearing the ovules develops all around the central axis.
Example: Dianthus, Stellaria.

The Dianthus is an example of a free central placentation.

Additional information:
- In placental mammals, the implantation of the embryo requires placental cells to become invasive, degrade the extracellular matrix, promote angiogenesis, migrate and evade the maternal immune system.
- These characteristics of placentation lead some to hypothesize that cellular processes used for implantation may be “reused”.
- Placentation in plants refers to the positioning of the ovules and takes into account the number and position of placentae, septa, and locules.
- Determining placentation requires probing or making a cross and or longitudinal- section of the ovary free central, is a type with the placentae along the column in a compound ovary without septa, such as in Caryophyllaceae.

Note: The depth of placentation various across placental mammals. The de3gree of placental invasiveness may be correlated to metastatic disease.