Wednesday, August 12, 2009

New to Science, Part II

Prepare yourself to enter the wonderful world of sedges, reader, a land shunned even by many a botanist. I know that the avid sedgaholics who follow this blog - both of them - eagerly await the following, though.

Sedges get an undeserved bad rap. Part of this stems from their sheer numbers: there are over 160 species in the genus Carex alone recorded from Ohio. Factor in Eleocharis, Schoenoplectus, Scirpus, Cyperus and the various other sedge genera and that's a lot of stuff to learn. But in my view, if one really wants to understand ecosystems to the fullest extent possible, a good knowledge of the flora is essential. The plants are driving most of the other, animal life forms found in any locale.

And sedges are VERY good barometers of habitat. Many species are quite specific to certain environmental niches, and can reveal much about the quality of the habitat that one is assessing. Plus, many of these sedges are just beautiful, and well worth more than a passing glance.

This one may not look like much, but it is one of the best plant finds in Ohio in many a year. Hats off to Rick Gardner for this coup. It is the Giant Sedge, Carex gigantea, which is new to the state. Not only that, but one will have to cover a lot of ground to reach the closest populations. This site is not far from West Virginia, but the sedge as yet remains unknown there. Kentucky has a few sites in four of its southernmost counties, and Indiana has a few populations in three southern counties. This Ohio site, in Gallia County, is at least a hundred miles away from any other stands of Giant Sedge.

Here's another extraordinary Gardner find from the same swampy floodplain woods. This specimen will be immortalized in an herbarium, but we took the opportunity to shoot images of the uprooted plant before bagging it. Lest you have concerns about harvesting a rare plant, there were lots of this sedge and they form extensive colonies. Collecting a sample like this harms it not in the least.

This one is Louisiana Sedge, Carex louisianica, and this is the third known Ohio site. Like the Giant Sedge, the Ohio populations are considerably removed from other locations. Note the long subterranean rhizome, connecting two pieces of the plant. This growth habit is how it forms sometimes extensive colonies. The spikey mace-like fruit are above.

Two of the rarest of the rare, growing side by side. Rick Gardner, on the left, kneels by a clump of Giant Sedge, and Ray Showman stands by a small colony of Louisiana Sedge. This is certainly the only site in Ohio where we know of such an occurrence, and it may be the only place for both anywhere north of the Ohio River.

But WHOA - what's this?! We stopped in our tracks when this vigorous jumbo of a plant materialized from the gloom of the swamp. It didn't take long to realize that we were looking at a hybrid, and one that we didn't recognize. Sedges in general are pretty faithful to their own, and crosses are not common for the most part.

That big grasslike tuft at the base of the sapling is the sedge - click the photo to enlarge - and the whitish-green spheres are the fruit. This is classic hybrid vigor - the cross outsizes either parent.
A closeup of the fruit of the hybrid. To briefly wax technical, the entire unit is called the spikelet, and each unit of the spikelet (the pointed things) are called perigynia. Perigynia are papery bladders that contain the actual seed, or achene in sedge-speak.

After some experience looking at these things, you can sort of tell a plant is probably a hybrid. The fruit have an unfinished empty look to them, and that's because they are. Hybrids typically have abortive, or undeveloped seeds, thus lending a weak hollow look to the fruit.

I've dissected a spikelet for your viewing pleasure, and we can clearly see the individual perigynia. Normal sedges have the perigynia filled plumply with hard bony seeds. Not this hybrid. There wasn't a seed to be found. So how will it reproduce? It won't, at least this one. It's parent species are long-lived perennials and this luxuriant hybrid will remain as a clone, growing from rootstock. But it might live for decades, who knows?

So, what is the thing? Well, we think we know. By analyzing the various elements of the hybrid, it looks to be a perfect cross between the aforementioned - and state-endangered - Louisiana Sedge and a much more common species called Gray's Sedge, Carex grayii. It should then be called Carex louisianica x C. grayii.

The above photo also shows something typical of hybrid plants. The hybrid is growing just in front of that big tree by the sapling, just in front and to Ray Showman's left. The bare area in back is much wetter and has standing water for lengthy periods, and that's where the Louisiana Sedge is growing. And we found plenty of Gray's Sedge a bit higher and drier on more elevated portions of the floodplain. The hybrid splits the difference in regards to habitat.

We'll look into this in more detail, and should be able to prove the hybrid's parentage. If it is what we think, such a hybrid has apparently never been documented so Rick and I may end up formally describing it.

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3 comments:

Scott said...

Wow... congratulations, Jim! How exciting to find what is potentially a new hybrid. That swamp forest sounds like a great place!

Weedpicker Cheryl said...

Carex gigantea was a HUGE find! Your account of the foray had me on the sedge of my seat the whole time!

Jack said...

Great to know about this..Thanks for the information..you got a great talent..

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Jack
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