Also found in: Dictionary, Thesaurus, Wikipedia.
an order of plants of the class Filicineae. (The Russian name for the order is also used to designate the subclass Marattiidae.) The stem is a flattened rhizome or a short, thick, tuberous trunk and is partially buried in the soil. The leaves have thick scales and often are very large (4-6 m); they are pinnate or less commonly palmate, with two fleshy stipules joined by an anastomosis. On the lower side of the leaves along the veins there are sporangia, merging in many species to form synangia. There are six genera, comprising approximately 200 species. At times they are classified in the single family Marattiaceae, with four subfamilies; other classifications designate four separate families of Marattiales. The plants grow in both hemispheres in the tropics or, less often, the subtropics. They are apparently the most ancient extant ferns. Fossilized plants dating back to the Paleozoic have been found. The stems and stipules of some species are rich in starch and are sometimes used for food. Large species are cultivated in greenhouses as ornamentals.