Tuesday, November 17, 2009

Autumn's Grape Fern


Long winter shadows set in at 3:40 p.m. that day, shadows impending sunset only 8 hours after I woke up. I spent the whole day outside on Wednesday, planting more daffodil bulbs, spreading leaf mold and compost everywhere, trying to gain as much sunlight-derived Vitamin D as possible. But merely being outside isn’t enough. My thrice weekly visits to the woods, even trashed out woods, seem to be integral to my health and well being. So I zipped across the ever-sprawling town and the complex network of late afternoon traffic to woodlands that likely haven’t burned in 80 years and are now under siege by a burgeoning deer population.

But grape leaf ferns (genus Botrychium) are out right now, harbingers of late autumn so I set out to find one before the deer ate it. I was a hair late as some woodland creature already took a bite out of the persistent deep green blade.

Four species of Botrychium can be found in Missouri’s woodlands throughout the year. B. virginianum is a delicate spring fern, popping up in mid-May throughout the Ozarks. B. biternatum is restricted to the Southeast Missouri Lowlands, and can be found during the fall next to the most common of the grape ferns, pictured, Botrychium dissectum var. obliquum. The elegant and deeply dissected B. dissectum var. dissectum grows in the eastern Ozarks, though remains somewhat uncommon. But B. dissectum var. obliquum is pretty common in low woods, ravines, cherty uplands, and grows in unburned sites with deer problems (so that must mean it's all over the Ozarks, she grumbles).

The grape leaf ferns all have a similar shape, each one sending up a triangular leaf-like blade. All but B. virginianum remain visible for months, even through winter. This is the time of year that you also might find a fruiting branch attached to the triangular grape fern leaf. This fruiting branch contains tiny round Pacman-like sporangia all crowded on what would otherwise have been a leaf. Most are a bit smaller than BB's. These Pacmen sporangia break open and release spores that produce new fern plants elsewhere. Some Botrychium species produce two triangular fronds side by side. My colleague swears that he once observed one frond of var. dissectum growing immediately next to one frond of var. obliquum. But were they from the same root structure? He refused to dig them up to find out.

6 comments:

Justin Thomas said...

Great post, Allison! Taxonomist have long debated whether the two varieities of B. dissectum require taxonomic recognition. Tryon, the father of American fern taxonomy, once reported seeing individual plants of B. dissectum growing dissected leaves one year and non-dissected the next. A buddy of mine from grad-school, Mike Barker, conducted molecular work on the complex and found that there is no genetic difference associated with the morphological difference between var. dissectum and var. obliquum. His study is a classic example of the short-comings of the morphological species concept. The fact that both share the same habitat and geographical distribution further solidifies the notion that this is likely one entity and that evidience for variety recognition is not defendable.

That being said, I still distinguish the two when I collect data. Science, and especially taxonomy, often waffles on its claims. You never know when someone will bring var. obliquum back.

Allison Vaughn said...

Similarly, in sand prairie country right now, and the weird little panic grass endemic here is definitely not the one found in the Ozarks. Push for it.

Ted C. MacRae said...

It is much easier to deal with two data sets found to represent one entity than one data set found to represent two entities! It's an almost absurdly frequent problem in insect taxonomy.

Nice post, Allison. I'm afraid I haven't made much progress on my pledge to better know the ferns. I made a good start in May, but then the insects busted loose and I stalled. I think I'll go look for some grape fern!

Allison Vaughn said...

You're right, Ted...

Also out right now is Dryopteris carthusiana and Christmas ferns. Saw both in the St. Francois Mountains this week! Tons of mosses and lichens, too!

Ted C. MacRae said...

Yeah, I saw my first B. dissectum yesterday (Ozark Trail, Wappapelo Section). I only recognized it because of this post (same thing happened last year with Tradescantia longipes). Most showed characteristics of var. obliquum, but a few var. dissectum were mixed in.

The area has been flooded and just in the last few days has been out of water. The plants were actively shedding spore - was this in response to the flooding or despite it?

Allison Vaughn said...

I bet it was in shock because of...
Glad you had a great hike! Neat country down there. HHT was a ghost town today, just the way I like it.