Fern “Things” – fertile fronds

(Question)

I have been growing several types of outdoor ferns in a shaded part of my garden for many, many years.  Several of my ferns (may be only one species), produce these “things” for lack of a better word. They are brown, “woody” protuberances (varying from about 18 inches to 3 feet high), very dry and not alive so to speak (i.e. they are clearly dead and can easily be cut down, and can keep for years before they eventually crumble to dust).  I cut them down and try to give them away to people who have/like dried flower arrangements. If I don’t cut them down they last over the winter and still are there in the spring. I would like to know what these things are called. What function/purpose do they serve? Do they eventually disintegrate if I do not cut them down? Can’t find any information on the Internet, so I am relying on your help.

(Answer)

With some further research, I can now answer your question. Ferns procreate using spores, not seeds. Many ferns spread using underground stolons whereby a new fern pokes up and unfurls the next year. Most of the time, when we think of ferns, we think of the order Filicales, you know, those that have fronds coming from a central cluster. Most of the time, the spores are produced in clusters of sporangia called sori (sorus is one sori). These occur on the underside of the frond and may or may not be covered by a flap of tissue called an indusium. You can see the sori on the underside of the pinnae of many ferns – they are often a rust or brown colour and come in various shapes, some, as noted, covered by a flap of tissue. If you ever have to key out a fern, these are very important features.

There are ferns (eusporangiates) that separate the fertile and sterile portions in their fronds. Interrupted ferns (Osmunda claytoniana) separate them on the same frond, hence its name – the fertile pinnae occur between the infertile pinnae along the same frond. The cinnamon fern (O. cinnamomea) has a completely separate, fertile frond. So do ostrich ferns (Matteucia struthiopteris). I think it’s these that you are seeing: they look like smaller, often burnt-looking or dark coloured fern fronds and are very stiff and persist over the winter.