The Collaborative International Dictionary of English v.0.48:

Heteroecious \Het`er*[oe]"cious\, a. [Hetero- + Gr. ? house.]
   (Bot.)
   Passing through the different stages in its life history on
   an alternation of hosts, as the common wheat-rust fungus
   (Puccinia graminis), and certain other parasitic fungi; --
   contrasted with aut[oe]cious. -- Het`er*[oe]"cism, n.
   [Webster 1913 Suppl.]