Step 1: Charophyte algae like Chara use special vernacular names for their reproductive structures instead of the usual oogonium and antheridium.
Step 2: The globule is the male structure that produces sperm, while the nucule is the female structure that houses the egg cell, surrounded by a spiral of tube cells.
Step 3: The other options wrongly assign nucule to a male role in Nitella, a sporangium in Coleochaete, or a vegetative propagule in Vaucheria, none of which match its actual identity.
Nucule is the \[\boxed{\text{female sex organ in } \textit{Chara}}\]