Article: An apparently heterosporous plant from the Middle Devonian of New Brunswick

A new plant of Lower or Middle Devonian age is described from Chaleur Bay, New Brunswick, as a new genus and species, Chaleuria cirrosa. It consists of a main axis bearing closely spiralled monopodial branches which in turn bear spirally arranged dichotomous ultimate branchlets. Pairs of sporangia terminate some ultimate branchlets. Macerations of sporangia yielded spores of two sizes (30-48 micro-m and 60-156 micro-m) which also differ from one another in shape and ornamentation. Our evidence suggests that the sporangia contained predominantly large or predominantly small spores or a mixture of both. We suggest that the spores of Chaleuria are sufficiently distinct to be considered as megaspores and microspores and that the planl presents evidence of an apparently early stage in the evolution of heterospory.