An article by Warren I. Pollock in The Hosta Journal (1998 Vol. 29 No. 1) discusses the fact that many variegated hosta cultivars are considered "unstable. " This means that all or individual divisions of the clump may revert to either a solid color or other form of variegation. You may end up suddenly have a single colored hosta or you will need to separate a solid colored division from the clump. Three nurseries were cited who include notations about "unstable " hostas. The following is a composite list of those cultivars mentioned: