Q.What is Nucule?

A nucule is the oogonium (female sex organ) of Chara, an ellipsoidal body topped by a crown of five spirally coiled tube cells, containing one egg.

Chara is a multicellular, branched green alga belonging to the Charophyceae, often called 'stonewort.' Its sexual reproductive structures are given special names distinct from the general algal terms 'oogonium' and 'antheridium':

• The male reproductive organ is called the globule, a small, spherical, orange-coloured structure that produces biflagellate sperm (antherozoids).
• The female reproductive organ is called the nucule (i.e., it is functionally the oogonium of Chara). It is an ellipsoidal/ovoid structure that develops on the plant body, surrounded by five elongated tubular cells that spirally twist around it, converging at the top to form a small crown (corona). Inside, the nucule encloses a single, large, non-motile egg cell (the oosphere). …