Look at the herbarium sheets of the gleicheniaceous Malaysian fern Dicranopteris . Compare with the fossil foliage of Gleichenia from the Cretaceous of Utah. The fronds are forked and have pinnatifid organization. The rhizome has concentric vascular cylinders with amphiphloic phloem. The annulus is oblique, stalks are short, and sporangia in a given sorus mature simultaneously.
Spores are smooth and triangular with a conspicuous trilete mark.
Look at the fossil foliage of Matondium . The Matoniaceae are thought to have an evolutionary relationship to the Gleicheniaceae, on the basis of reproductive structures. The genus Onoclea is placed within this complex which is characterized by ferns with erect to long, creeping stems with trichomes, scales or both. Compare the herbarium sheet of extant Onoclea to the photographs of fossil Onoclea found in the Paleocene of Alberta, Canada. The Heterosporous Water ferns 1.