Simulation · Biology · Class 11

Where do the ovules sit?

From the lesson Gynoecium and placentation in Morphology of Flowering Plants. Change the values and watch what happens.

The idea behind it

NCERT §5.5.1.4, Figure 5.12

The gynoecium is the flower's female reproductive part, made of one or more carpels.
A carpel has three parts: the ovary (the enlarged base), the style (a long tube above it) and the stigma (usually at the tip of the style), which is the surface that receives pollen.
Each ovary carries one or more ovules attached to a flat, cushion-like placenta.
Apocarpous: two or more carpels that stay free, as in lotus and rose. Syncarpous: carpels fused, as in mustard and tomato.
After fertilisation the ovules become seeds and the ovary ripens into a fruit.
Placentation is the arrangement of ovules inside the ovary.
Marginal: the placenta is a ridge along the ventral suture and the ovules sit on it in two rows. Example: pea.
Axile: a multilocular ovary with the placenta along its central axis, carrying the ovules. Examples: china rose, tomato, lemon.
Parietal: ovules grow on the inner wall of the ovary. The ovary is one-chambered but becomes two-chambered by a false septum. Examples: mustard, Argemone.
Free central: ovules on a central axis with no septa (Dianthus, Primrose). Basal: the placenta is at the base of the ovary and bears a single ovule (sunflower, marigold).

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