Saturday, June 6, 2009

A tale of two ferns

I have been remiss in blogging vegetable matter of late, and I know that at least some people who scan this blog like plants. We all should; without them there would be no animals, including us. Anyway, on a foray into Shawnee State Forest a few weeks back, I happened upon an interesting assemblage of ferns.

A lush bank in the lushest of eastern North American habitats: the great Eastern Deciduous Forest. This scene caught my eye, as growing intermixed are two of our largest, most spectacular ferns, the Cinnamon Fern, Osmunda cinnamomea, and Interrupted Fern, O. claytoniana. Both are common in the right haunts, but aren't often bedfellows.

We shall move in for a closer look at these spore-bearing wonders.

A big Cinnamon Fern can arch three or more feet skyward, and when they are at their sporulating best the plants are real showstoppers. For people with a penchant for using native plants in their landscape, this'd be a goodie.

The namesake of the fern - these gorgeous cinnamon sticks. Cinnamon Fern is dimorphic; that is, the sterile chlorophyll-bearing leaves are distinct from the short-lived ferile leaves that produce the spores (fern seeds). A foot long+ cinnamon stick like these produce countless thousands of minute spores, which when ripe will be launched to the winds. Some of them could sail to Siberia, who knows.
Cinnamon Fern is not that common in Shawnee State Forest, where I took these shots. It is more a species of extremely saturated soils, such as occur along the margins of bogs and in swampy woods, etc. However, some of the forested slopes in Shawnee have spring outflows, which create mucky quagmires suitable for this plant.

In slightly better drained microhabitats in and around the Cinnamon Fern were luxuriant tussocks of Interrupted Fern, as seen above. To me, it doesn't have quite the panache of the former, but it isn't far behind and can grow nearly as large. Interrupted Fern is a classic inhabitant of rich, mesic (moist) forested slopes.

A quick glance and it looks the innards of the fern are dying. Black clumps of dead foliage hang from its inner stems.

But wait - those blackish clumps are actually the spore-bearing fertile leaves. As they grow on the sterile leaves and right in the center of the frond, the sporulating fronds break up the leaf - hence the name Interrupted Fern.

Even when these similar-looking jumbo ferns have passed from their relatively short-lived fertile stage of spring, it isn't too tough to separate them. The frond above shows the tip of an Interrupted Fern frond. Note how it is broad and rounded, and the individual segments, or pinnules, are rather robust, smooth, and oval-shaped.

This is the frond of a Cinnamon Fern, which is much more acute, or pointed, at the terminus. The pinnules are denser and not as robust - an all, a very different vegetative appearance.


ben said...

Nice post. Thanks for throwing the botanists a bone. ;) But you do a great job with all your posts. It is fun to learn about unfamiliar things like Tiger beetles and Darters in the Big Darby.

Scott said...

Hi Jim. Thanks for the plug. Like Ben, I really enjoy reading your posts and learning about organisms I know nothing about. Keep up the great work!

Heather said...

Nice post on the ferns. Yes, I would have to say that my ID of cinnamon fern in my garden is incorrect. Oh well. I think maybe I have seen interrupted fern somewhere before. The shape of the pinnules is very distinctive. There is something about their shape that is reminiscent of the wings of a Luna Moth.
Thanks for the very informative post!