THE GENUS GYMNOSPORANGIUM IN EASTERN CANADA

Abstract

Nine species of Gymnosporangium native to Eastern Canada and one commonly intercepted on imported nursery stock, but not known to be established, are described, illustrated, and discussed. Species occurring in adjacent United States but unknown in Eastern Canada are briefly mentioned. G. connersii sp. nov. and Roestelia brucensis sp. nov. are newly described on Juniperus horizontalis. R. brucensis is noteworthy because it has a repeating aecial stage and lacks telia. This is the first example of repeating aecia occurring in the genus. Aecial and telial keys are presented, emphasizing characters that permit identification in the field. One such character is the date of aecial maturity; it is suggested that this is a ready means of verifying apparent differences in morphology between taxa in this genus.