Lesson 7 of 13 · 9 min
Ovary position on the thalamus
NCERT §5.5, Figure 5.9
At the market, Nithya notices that a guava and a cucumber carry a small dry crown of old flower parts on the end away from the stalk. A brinjal carries its sepals at the stalk end instead.
The lesson in notes
In short
Flowers are classed by where the calyx, corolla and androecium sit on the thalamus compared with the ovary: hypogynous, perigynous or epigynous.
Hypogynous: the gynoecium is at the top and every other part is attached below it. The ovary is superior. Examples: mustard, china rose, brinjal.
Perigynous: the gynoecium is in the centre and the other parts sit on the rim of the thalamus at nearly the same level. The ovary is half inferior. Examples: plum, rose, peach.
Epigynous: the margin of the thalamus grows up around the ovary, encloses it fully and fuses with it, so the other parts arise above the ovary. The ovary is inferior. Examples: guava, cucumber and the ray florets of sunflower.
Superior, half inferior and inferior describe the ovary; hypogynous, perigynous and epigynous describe the flower. The terms come in matched pairs.
Quick check: if you see the sepals and petals attached on top of the ovary, as at the crown of a guava fruit, the ovary was inferior.