In a comparative ecophysiological study of two fern species (Athyrium filix-femina and Anisocampium niponicum) growing in the same microenvironmental patch among other ferns on a north facing slope in Palisades, N. Y., the two species had similar maximum photosynthesis rates (3.6 and 3.1 µmol m^–2 s^–1, respectively), but the light intensity (PPFD) required to reach saturation was somewhat higher for A. niponicum compared to A. filix-femina. The dark respiration rate was higher for samples from A. niponicum (0.54 µmol m^–2 s^–1) compared to A. filix-femina (0.40 µmol m^–2 s^–1). Leaf stomatal density expressed as number cm^–2 was higher in A. niponicum (4,538) compared to A. filix-femina (2,660), although stomatal size in the two species was fairly similar (c. 48 – 54 µm length and 28 – 30 µm width). The chlorophyll content index (CCI) for A. niponicum was higher (4.72) than A. filix-femina (2.99). Based on leaf fluorescence analysis, Ψ_o (efficiency with which a trapped exciton can move an electron into the electron transport chain) was higher in A. niponicum (0.73) than A. filix-femina (0.66). The significance of this remains to be determined, but may indicate that higher chlorophyll concentrations correlate to a greater stability of the elevated energy electron (exciton) in PS2 reaction centers due to electron quantum resonance coherence among the light harvesting molecules, and a resulting increased probability that the electron will pass on to the intermediate quinone and beyond in the electron-transport chain.