Chalaza

Chalaza, a Greek word meaning a tubercle, is applied in botany to the structural base of the ovule (q.v.), at which point the vascular bundle of the seed generally terminates, and the integuments (secundine and primine) spring from the body of the ovule (nucellus or tercine). In inverted or anatropous ovules the chalaza is actually at the top of the ovule, i.e. at the end farthest from the placenta. In the exceptional type Casuarina the pollen-tube pierces the chalaza, whence Treub has separated this genus from all other angiosperms as a subdivision Chalazogamae.