Flower ovary and placenta

The  Ovary encloses ovules. These are structures that contain eggs which, after fertilisation, will develop into seeds. Click HERE to learn more about pollination and fertilisation. The ovules are attached to a part of the ovary known as the placenta and this is where the pollen tube enters the ovule during the process of fertilisation. The stalk that attaches the ovule to the placenta is called the funiculus. The ovary may have one or more chambers. These are known as locules. The ovary may have a single locule (unilocular) or may be divided (multilocular). Each locule may have one or more ovules. The compartments are separated by walls called septa. The arrangement of placentas in the ovary is termed placentation. There are several types.

A flower ovary contains ovules, which are attached to a part of the ovary known as the placenta. Four types of placenta are shown here.

A placenta can form at the base or apex of a single locule  and this is termed  basal or apical placentation. Other types of placentation are:-

pea flower ovary and placentas

marginal placentation. Ovules attache to the wall of an elongated ovary along its ventral suture, also known as its margin as in the Pea family, Leguminosae.

carnation flower  ovary and placenta

free-central placentation. Ovules attach to a central column  as in the Pink family, Caryophyllaceae.

daffodil flower ovary and placenta

axile placentation. Ovules attach to the central axis of a multilocular ovary as in the daffodil

poppy ovules and parietal placentation

parietal placentation. Ovules attach at several points on the wall or outgrowths from it, as in the Poppy family, Papaveraceae. Parietal means ‘of a wall’.

A Carpel consists of an ovary, a style and a stigma. A flower may have 1 or more carpels that collectively make up the Gynoecium, the female part of the flower, which is  called the Pistil. The ovary becomes a fruit and the ovules become seeds.