Fall Flora of Oak Woodlands

It should be celebrated, for two reasons: 

 

First, it’s beautiful and an inspiring finale to the growing season.

 

Second, a diverse and conservative fall flora is an indicator of woodland health, a rare thing today. Most woods have lost it. 

Somme Woods has benefitted from ambitious restoration (fire, thinning, and seeding) for four decades. It's a good place to get to know these important late-season plants. 

 Migrating birds harvest the insects that spend their lives in the woodland understory, and our eyes harvest the richness of its shapes and colors. 

Part 1. Two Goldenrods and Two Asters

Few people recognize such plants as Zigzag or Blue-stemmed Goldenrod. The handsome plant below is the zigzag one. It once was widely common in the oak woods. Now most woodlands don't have any. 

It's short and cute, often just a foot or two tall. Most of the fall plants in a high-quality woods are one to three feet tall. You can recognize Zigzag Goldenrod by its wide, toothy leaves. The stem does zig and zag a bit. The flowers are mostly in a clump at the summit. And there's another goldenrod in this photo, on both sides of the zigzag, with narrow leaves, shown better in the photo below:

Blue-stemmed Goldenrod is also a mark of quality. Its flowers are spread along the stem, emerging from the bases of the leaves. And the stem is indeed often blue or purple. 

In the photo below, three goldenrod species mix with three aster species:

Blue-stemmed is in the middle. One half of a Zigzag leaf is visible at the bottom. But the main plant here is Elm-leaved Goldenrod, easy to miss now because it's a late-summer plant, mostly finished blooming in October. (It's another one that's about two feet tall; its seeds are forming where the flowers were, on widely branching stems, visible here if you look close.) 

And then come the asters. The blue ones above are Short's Aster. The other, Forked Aster, is identifiable (lower right) by its tall stems and heart-shaped, toothed leaves; it normally has white flowers, but this year the deer ate the tops off most of them, including those here. 

In most woods you'll find no Short's Aster. Its place will be taken by the weedy Drummond's Aster. It takes a second look to differentiate the high-quality Short's (C = 8) from Drummond's Aster (C = 2). Both have blue flowers, but their leaf stems are different, as shown below:

The classy Short's Aster (right) has a thin leaf stem. The weedy Drummond's (left) has a stem that looks wide because of leaf-like "wings" along the sides. If you care about woodland health and biodiversity, seeing Short's Aster makes you feel good!

It's striking how different Somme is from nearby unrestored woods. 

For comparison, let's look at three photos from two nearby oak woods. This first woods has not had the benefit of fire:

The fall understory is mostly slow-growing maple seedlings, a few years old. Most of them will die from the competition. But a few, like those straight, skinny trunks here and there, will continue to completely shade out any oak reproduction and most of the oak flora and fauna. It's increasingly too dark for the ecosystem that was here. The red oaks, like that large dark trunk to the left, and the white oaks, like that ghostly large trunk in the distant center, will be the last of their kind here, unless good care for biodiversity arrives.

Nearby is a woods that has had some minimal restoration. It's been burned, as indicated by the blackened stump and by the fact that the older maple seedlings have been burned off.

Another shot of this minimally managed woods:

Mostly bare ground. The dark tree on the right is a red oak. The pale tree in the center is a white oak. They have long been without the fire that oaks woods need. The skinny, young trees are again maples. Despite the relatively mild, low-creeping fires, the oaks will not reproduce under the maples. Many trees would need to be thinned (or impractically more intense fire conducted) for this ecosystem to start to recover its natural biodiversity. For more on oak woods conservation, see Re-discovering Oak Woodlands and Blunt Answers to Nine Questions about Saving Oak Woodlands.

Now, for the fun of it, back to the happiness of Somme Woods. Increasingly, it's a rollicking fine woods. More and more people are appreciating how special it is. 

In the photo above, Short's Aster is joined by Showy Goldenrod, a rare plant in today's woodlands. Years ago, only a few survived on the edges of old fields here. Now it's reclaiming its place in the open woodlands, recovering thanks to controlled burns and the hard work of stewards thinning over-stocked trees. 

Though I like the plant a lot, I find it hard to get a good photo of Big-leaf Aster (above). The flowers are too high above the leaves. In this photo, the flowers just float, disconnected. The aster's leaves are the only wide ones. Most other plants here are Elm-leaved Goldenrod, but the one bottom-center with the white seeds is Woodland Puccoon or Broad-leaved Puccoon.

Speaking of puccoon...

... here it is again, lower right, this time with Short's Aster and two goldenrods, Elm-leaved and Blue-stemmed, at the base of an old oak.

The seeds of this rare Puccoon remind us that collecting and broadcasting them throughout good habitat is a crucial part of the Somme Plan. When we started, Somme Woods had perhaps a dozen plants, all in one small area. Now they're spread by the thousands over hundreds of acres. Yes, good. 

To some people perhaps, the "fall flora" refers just to plants in bloom. But we're at least equally inspired by the richness of seeds. :

Here, among asters, goldenrods, and others are the berries of Spikenard (purple) and Doll's Eyes (white and red). We let the birds eat some, and we gather some. Indeed we annually gather hundreds of gallons of rare seeds, those little "packages of the future" representing hundreds of species of plants. Then we broadcast them where they're not. That's how diversity gets new starts.

Remember those deer-eaten Forked Asters? They are Endangered in the Illinois and Wisconsin woodlands. The photo below is from a previous year with fewer deer:

Forked Aster is a surprise. I'd never seen it until Tom Vanderpoel found a little patch in a rich woods near Barrington. According to our approved plan, we restored this refugee species to Somme by throwing a few seeds in the right places at the right times. Now it's thriving by the thousands. The photo below shows a new patch just getting started:

After brush control and a burn, on mostly bare soil, it's flowering next to an irruption of weedy Beggars' Ticks. But the weeds are very temporary. Conservative sedges, asters, and others will soon out-compete them. 

On the other hand, we've found that the Forked Aster will do this:

The whole middle of this photo is Forked Aster, having wiped out all competition as it spread. Our hope, goal, and expectation is for diversity, not the monopoly of a species or two. And sure enough, as the restoration matures, the Endangered but temporarily over-exuberant Forked Aster increasingly plays well with others.

Not to suggest that all is well, or all goes according to plan, in this early stage of oak woodland restoration science. The photo below is from a series taken along a trail in 2013:

In this area, thanks to increased sunlight and lack of sufficient seed, the weedy Tall Goldenrod (C = 1) has taken over and suppressed most other species. We monitor it. When we photographed the same area again, in 2019 ...

... it was pretty much the same. Experiments are under way to deal with various monopolistic species. Bit by bit, we seem to be better and better ecosystem medics.

One last photo: 

They're gone - the bison and elk that once lived off the vegetation under our oldest oaks. But most of the species that once lived here are recovering a rich biodiversity that will be our generation's contribution to the people and planet of the future.