Sunday, February 24, 2008

Expecting the Unexpected

To some extent, a foothills canyon is a familiar, known entity. Delightful to explore, but rarely yielding surprises. Or maybe I’ve just been spending too much time in the lower elevations. But last summer’s visits to a hidden gulch just 2,000 ft (610 m) higher than my usual whereabouts brought new discoveries for me, and seemed a rare treat even to the more experienced botanists I took along on future visits. Everyone got excited about this place!

First, that fern. It was everywhere here in the gulch, but I had never encountered it elsewhere. Patience for keying is never my strong suit, but this little guy fell out indisputably at the 4th fern couplet, without a hand lens. That's my kind of fern! My real botanist friends later confirmed the identification. Among Colorado’s modest fern flora it is exceptionally recognizable. The Northern Oak Fern (Gymnocarpium dryopteris) is reasonably rare in Colorado. It had been reported from one locale in my county, but never from this nearby county.

Here's a close-up, courtesy of Priscilla, of those beautiful sori that cinched the ID, if we could have been mistaken before. The fact that they are naked, lacking indusia, and not marginal, separates this from, guess what?, Bracken Fern (Pteridium aquilinum), just in case its delicacy and grace were not enough to distinguish the two.

With a substantial surprise like that right at the start, we began to expect the unusual. Sure enough, more surprises awaited around every twist in the gulch. One after another, plants that were doing quite well here, thank you. I guessed many of these moisture lovers, including my little fern, would be more familiar to readers of eastern North America than they are to me. I may have been wrong.

Let’s start with the wintergreens, all low ground covers with attractive flowers.

Single Delight (Moneses uniflora, Pyrolaceae)
Tiny and shy, this little wintergreen is pretty well established in appropriate parts of Colorado, that is, moist subalpine forests from 8,000 to 11,800 feet (2440-3600 m). It is, however, threatened or endangered in Connecticut, Ohio, and Rhode Island, although it does better in New England and is secure in Canada. You have to make a real effort to see its flower-face, always cast downward and held barely an inch above the ground.

One-sided Pyrola (Pyrola secunda, Orthilia secunda, Pyrolaceae)
Just slightly taller than Moneses is this related species, but its flowers are clustered at the top of their stalk. Widely distributed in mountainous western Colorado from 8200 to 13,000 feet (2500-4000 m), it has been found as low as 7000 ft (2130 m) in exceptional situations. But it seems to be losing ground in the east: strong across southern Canada, as well as in New England and New York, it is threatened or endangered south of about Pennsylvania. It was historically reported as far south as Virginia.

Pink Wintergreen (Pyrola asarifolia, Pyrola rotundifolia var. asarifolia, Pyrolaceae)
Similar story here: threatened or endangered, according to some sources,* in Indiana, Iowa, New York, Vermont, and New Hampshire, secure and broadly distributed in southern Canada.

Many more of our discoveries await description: the orchids I failed to capture in photos and those that we were too late to see at all but suspect are there. All the "berries": bunchberry, baneberry, cranberry (sort of)... And of course the special lichens and mosses and liverworts. An entire post will have to be devoted to the fungi. This gulch will feed my foothills fancies for a long time.

All of these plants have a circumboreal distribution. Not in the far north (boreal or arctic), but as close to it as they can comfortably get. In effect, our hidden gulch was in a small peninsula of the Canadian forest, extending down the Rocky Mountains into and through Colorado. When we find these special plants, we recognize them as fringe species, far from home at the edge of their range, hanging on in small patches of cool, mesic habitat wherever possible. They occupy a narrow coastline in a habitat no longer characteristic of Colorado.

There’s a small picture here: this one tiny gulch, about a half-mile (1 km) long and a few hundred yards or meters wide. On this scale, our gulch seems to be a little piece of Subalpine Forest transported downslope, thanks to the cool north-facing slope and the narrowness of the shadowed defile. There was some Englemann Spruce (Picea englemannii), but the co-dominant Subalpine Fir (Abies lasiocarpa seemed to be missing. (This year, I'll search the overstory more carefully.)

But there’s also a larger picture: an image of glaciers flowing across a continent and down from mountain peaks, figuratively pushing a host of plants and animals ahead of the ice and cold. The glaciers have retreated, and the plants follow their favored habitat. The unsettled or alarmed status these plants are given in many states reflects a readjustment on a continental scale, telling us we’re no longer in the Pleistocene. A process underway for the last 10,000 years, this geographic adjustment will be only more visible, more accelerated, in the decades ahead. How much longer will we be able to find these unexpected treasures?

What one finds... will be what one takes the trouble to look for.
—Joseph Wood Krutch

This and the preceding post are submissions for the plant carnival Berry-Go-Round; edition #2 to be hosted soon at Further Thoughts.

*Explore plant distributions by typing in species names at the USDA Plants Database or at NatureServe. Note that the status categories don't always match, or exactly reflect state records, and they can also vary by subspecies.

1 comment:

Anonymous said...

Several of the plants you mention are very common around Sitka, especially the Oakfern and the Single Delight (aka, Shy Maiden). If you get back there again when they are in bloom, you might try smelling the flower, around here they have a very nice lemony scent.