Phyletic Lines in the Modern Ferns

Before we can begin to discuss overall phyletic lines of ferns, we must ask ourselves rather old and trite but nevertheless crucial question, is a fern? From what we know of fossil record there were no true in Devonian, but there was a great array of now extinct groups of so-called in Carboniferous. How do we circumscribe group, and is there any reason to question naturalness of this taxon? Traditionally we define it as any megaphyllous plant reproducing by spores. From great diversity of plants that we have seen placed in the ferns in fossil record it seems quite possible that some groups could well have arisen separately from Devonian or Carboniferous ancestors before we would have called them true ferns. I am not proposing that we answer question at this moment, nor am I certain that we can answer it at this point in time, but I want to keep question open as we address ourselves to overall view of evolutionary lines as seen in modern ferns. Another major difficulty that must be mentioned before we can begin is that morphologically we are still in somewhat of a mess regarding characters of ferns. In an attempt to prepare an objective way of producing a phylogeny with aid of computerization, systematic characters of were examined rather closely. A broad comparison is extremely difficult or impossible at this time. What are characters? We actually know little about any of them. In first place in many cases we cannot make comparisons between taxa. We may have information on certain characters for certain taxa, but it generally is difficult to compare information we have between major groups of ferns. Secondly, we do not know what we are looking for in all characters. For example, in most descriptions of their vestiture is described as consisting of hairs or scales and only rarely with any sort of qualifiers, such as clathrate scales or acicular hairs. In some cases same type of scale or hair is described as being present in totally different and unrelated groups of ferns, yet no detailed study has been made to see whether in fact two are really same. We have virtually no information on another aspect of vestiture, namely paraphyses. What types are there? What is their importance to plant? What is their phylogenetic significance? There are many other characters in just this same state of non-recognition. The work of Bower along these lines was extremely important, but work is far from finished. We are still in crosier stage of morphological and phylogenetic study in ferns. The study of phyletic lines in has taken into consideration in past virtually exclusively modern and ignored fossil ferns. The reasons for this are good ones. The of Paleozoic are extremely diverse and