Index Filicum

Index Filicum is a discontinued series of botanical indices on ferns, started by Carl Christensen in 1906 and continued in the form of seven supplements by Christensen and other authors until 1997. As of supplement 5, the index also covered lycophytes and horsetails. There was an earlier work of the same name by Thomas Moore, published in eight volumes between 1857 and 1863.
The forward to supplement seven stated that the supplements would be issued every five years from then on. However, since then, no further volume has been issued. Kew Gardens, the publisher of the two most recent supplements, has decided instead to rely on the International Plant Names Index (http://www.ipni.org/index.html — online).