This section is from the book "Commercial Gardening Vol2", by John Weathers (the Editor). Also available from Amazon: Commercial Gardening, A Practical & Scientific Treatise For Market Gardeners.
A genus of dwarf tufted ferns with pinnate fronds and roundish clusters of spore cases. They may be grown in the same way as the Hart's Tongue Ferns, in moist and shaded spots. The best-known kinds are: hyperborea (alpina), from the wet alpine rocks of North Wales and Scotland, having tufts of lance-shaped fronds 3 to 6 in. long; ilvensis, closely related but with broader fronds; obtusa, from North America, and polystichoides, from Japan, are other species.