Abstract:What is the simplest fern in existence? It is not Asplenium Trichomanes with its short wiry midrib and small pinnae. It is not even Trichomanes Petersii with not much more than a pinna of leaf tissue ...What is the simplest fern in existence? It is not Asplenium Trichomanes with its short wiry midrib and small pinnae. It is not even Trichomanes Petersii with not much more than a pinna of leaf tissue and leaves one cell thick. These are perhaps the simplest ferns in the United States from the standpoint of size and structure. The simplest known fern is a native of the tropical East Indies, a species of the genus Monogramme Schkuhr, M. dareaecarpa Hooker. In this plant, each leaf has but one vein and one fruit dot or fruiting line, set in a groove along one side of the leaf. The placing of the sporangia was responsible for the original specific name, dareaecarpa, after Darea, a group of ferns generally placed under Asplenium. The plants are epiphytic and grow mixed with mosses on the bark of trees: The stem, like the leaf, has a single solid wood fiber traversing it, only a few cells thick. The relationship of Monogramme is with the fern tribe Vittarieae. Vittaria, a single species of which, V. lineata, occurs in Florida, always has two lines of sporangia while Monogramme has but one, but in venation, the largest species of Monogramme is almost a duplicate of the smallest Vittaria.Read More