(botany) A seedcapsule in the form of a box, the seeds being released when the top splits off.
1979, Organization for Flora Neotropica, New York Botanical Garden, Flora Neotropica: Issue 21, Part 1, p. 221:Key to Species of Cariniana Inflorescence predominantly terminal and subterminal; pyxidium without teeth at line of opercular dehiscence.
1924, Samuel James Record, Clayton Dissinger Mell, Timbers of Tropical America, p. 467:The pyxidium has the trigonoidly cylindrical or obconical form of that of Couratari, but it is much thicker, heavier, and more solid in substance.
1913, Georges Victor Legros, Fabre: Poet of Science, p. 176: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".
1836, Asa Gray, Elements of Botany, p. 221:A fruit of this kind is sometimes termed a pyxidium; that is, a little chest.
