Distribution and systematics of Batrachospermum (Batrachospermales, Rhodophyta) in North America .8a. Section Batrachospermum: Batrachospermum gelatinosum

Eighty-six populations of Batrachospermum gelatinosum were examined from throughout its known range in North America and were compared using multivariate morphometrics and image analysis. Morphological variability was as great in individual populations as that measured among locations. Populations pooled for each biome showed a north-south trend in whorl and carpogonium size. The mean measurements for the tundra were significantly smaller in whorl diameter and larger in carpogonium size than those for the coastal plain. B. gelatinosum is widely distributed in North America, having been collected from the north slope of Alaska and Baffin Island in the north to Texas and Louisiana in the south. In addition to the populations analysed, herbarium specimens from North America were examined and confirmed locations in 17 US states, four Canadian provinces and the Yukon territory were added. Three populations, two from the boreal forest (Newfoundland) and one from the deciduous forest (Rhode Island), were examined for morphological variation throughout the growing season. The two Newfoundland populations were observed year-round, whereas the Rhode Island population was present only from October to June. Carposporophyte diameter showed a spring maximum in all three populations. In addition, there were seasonal trends in whorl diameter, carposporophytes per whorl and carpogonium length in the Rhode Island population.