aecium

Etymology
From, from. However Merriam-Webster relates that aecium is a back-formation from aecidium and is not related to the Greek. The word aecium was "introduced as a substitute for aecidium by the Purdue University plant pathologist J. C. Arthur (1850–1942) in an effort to reform terminology for rust fungi; see Terminology of the Spore-Structures in the Uredinales, Botanical Gazette, vol. 39 (Mar., 1905), pp. 219-22."

Noun

 * 1)  A cuplike fruiting structure of some parasitic rust fungi that contains chains of aeciospores.
 * 2) * 1932 August, Ralph Ulysses Cotter, Factors Affecting the Development of the Aecial Stage of Puccinia Graminis, US Dept of Agriculture, Technical Bulletin No. 314, page 29,
 * The writer therefore made observations to determine the conditions under which the aecia open and discharge spores most readily.