No question is silly if you are curious about the answer. Dryopteris erythrosora, Autumn Fern, is also commonly known as Japanese Shield Fern. It has a slow spreading habit and an ability to tolerate neglect which makes it an ideal candidate for use as a groundcover here in Northeast Florida. Autumn fern is one of the few ferns to have seasonal color value; the newly forming fronds appear red to purple in color when young. It is this combination of colors on the new growth which give it the name autumn fern. It will grow to about 18 inches tall with single plants spreading no more than 24 inches. It requires very little care, tolerates most any kind of soil but must be grown in partial shade to full shade. For more complete information, please look at the University of Florida publication by Dr. Ed Gilman: http://edis.ifas.ufl.edu/fp189
I have a very shaded lot and I have been adding ferns to my landscape. I know this is a silly question, but I want to know why they call my most recent purchase an autumn fern.