Sword Fern

Of all the ferns used in landscape work, Nephrolepis cordifolia is the one that will actually take the conditions. Narrow upright fronds, tolerance of poor soil and low light, and small underground tubers that carry it through dry spells make it far tougher than it looks.
It runs on stolons and colonises quickly, which is the point of it as a cover plant and the problem with it near natural bushland. It is a listed environmental weed in Florida, Hawaii, South Africa and parts of eastern Australia.
The Sword Fern is the practical choice for shaded ground cover, provided the site can accept a plant that spreads on its own terms.