Complex sentence: There is either no frond dimorphism or only mild dimorphism, either open venation or very simple anastomosing, sori mostly reniform and have indusia, except for the "Phegopteris" group.
Split into simpler sentences: There is either no frond dimorphism or only mild dimorphism, either open venation or very simple anastomosing. The sori are mostly reniform in shape and have indusia, except for the "Phegopteris" group.