pyxidium

1. (botany) A seed capsule in the form of a box, the seeds being released when the top splits off.Examples: "Key to Species of Cariniana Inflorescence predominantly terminal and subterminal; pyxidium without teeth at line of opercular dehiscence."; "The pyxidium has the trigonoidly cylindrical or obconical form of that of Couratari, but it is much thicker, heavier, and more solid in substance."; "The capsule of gold−beater's skin, in which the grubs of the Cione are enclosed, divides itself, at the moment of liberation, into two hemispheres "of a regularity so perfect that they recall exactly the bursting of the pyxidium when the seed is distributed"."