Key points are not available for this paper at this time.
Harry L. Boston, Michael S. Adams, Productivity, Growth and Photosynthesis of Two Small `Isoetid' Plants, Littorella Uniflora and Isoetes Macrospora, Journal of Ecology, Vol. 75, No. 2 (Jun., 1987), pp. 333-350
Boston et al. (Mon,) studied this question.