|| Leaf vein patterns of ferns are highly stable at genus and family level. The vein patterns include free vein, reticulate vein and mixed type of above two. The evolutionary direction of the fern venation is from free veins toward further dividing into anastomosing venation. |
In this study, observations on the venation were made for 53 species of Taiwan Polypodiaceae ferns. Two basic patterns were found : mixed and reticulate. The growth of the venation can be divided into three types : r type, Y type and T type. The r type was found in Pyrrosia ; the Y type was found in Drynaria, Aglaomorpha, Polypodium, Leptochilus and Loxogramme ; and the T type was found in Arthromeris, Selliguea, Lemmaphyllum, Lepisorus, Colysis, Microsorum, Phymatosorum and Neocheiropteris.
The leaf venation patterns of venation in Polypodiaceae can be divided into seven modes in three lines, with each genus has its own common characteristies. This study of vein pattern demonostrates its important role in the investigation of fern evolution.