Large Serrate Leaf Pyrrosia , P. lingua var kei kan (sometimes called monstifera) is extremely easy to cultivate. I have maintained this variety for over 25 years and have never experienced any problems with its care. It is quite vigorous, quickly fills up a 10 inch basket and produces large very wide fronds. At maturity, individual leaves can be 14 inches long and 4 inches across at the middle. The margins are deeply lobed with many finger like divisions. The fronds are fairly symmetrical with very little twisting of the blade. It does produces fertile fronds with spores after a few years of maturity. I consider this variety to be uncommon at present in US collections.  Nearly identical to variety "Hiryu" but "Kei Kan" leaves get much larger.