If C-Fern gametophytes are given an initial light exposure (one to two days under standard conditions) to initiate germination and then placed in the dark, their growth form will be dramatically altered. The alteration in some ways resembles the etiolation response that is well known for higher plants, in which plants subjected to dark conditions grow substantially longer than those in light. In dark-grown C-Fern gametophytes, some of the basal cells undergo extreme elongation which results in strap-shaped structures consisting of a few highly elongated cells just above the spore coat and a pad of smaller cells at the tip of the gametophyte. In gametophytes containing the det30 mutation, which was induced by X-rays, this elongation response is reduced. In contrast to flowering plants, both C-Fern wild type and det30 gametophytes grown in the dark still have the capacity to synthesize chlorophyll, although they are typically a very light green.

The non-etiolated genotype is currently available only as a double mutant with her1. This enhances visualization of the non-etiolated det30 phenotype in dark-grown cultures.

Cooke, T. J., R. H. Racusen, L. G. Hickok and T. R. Warne. 1987. The photocontrol of spore germination in the fern Ceratopteris richardii. Plant and Cell Physiology 28: 753-759.