In some species of ferns, there is virtually no difference between the fertile and sterile fronds, such as in the genus Dryopteris, other than the mere presence of the sori, or fruit-dots, on the back of the fronds. Some other species, such as Polystichum acrostichoides (Christmas fern), or some ferns of the genus Osmunda, feature dimorphism on a portion of the frond only.
In some fern species, there is almost no distinction between fertile and sterile fronds, such as in the genus Dryopteris, except for the presence of sori on the back of the fronds. Some other species, like Polystichum acrostichoides (Christmas fern) or certain Osmunda ferns, exhibit dimorphism only on a portion of the frond.