A genus of ferns belonging to the family Polypodiaceae and having rounded naked sori

Usage examples of polypodium.

And lower down the great forest trees arch over it, and the sunbeams trickle through them, and dance in many a quiet pool, turning the far-down sands to gold, brightening majestic tree-ferns, and shining on the fragile polypodium tamariscinum which clings tremblingly to the branches of the graceful waringhan, on a beautiful lygodium which adorns the uncouth trunk of an artocarpus, on glossy ginger-worts and trailing yams, on climbers and epiphytes, and on gigantic lianas which, climbing to the tops of the tallest trees, descend in vast festoons, many of them with orange and scarlet flowers and fruitage, passing from tree to tree, and interlacing the forest with a living network, while selaginellas and lindsayas, and film ferns, and trichomanes radicans drape the rocks in feathery green, along with mosses scarcely distinguishable from ferns.

But if you ask Polypodium calcareum--How is it you choose only to grow on limestone, while Polypodium Dryopteris, of which, I suspect, you are only a variety, is ready to grow anywhere?