A Walk up the Plant Evolutionary Ladder … All the Way to Flowers

A walk up the Plant Evolutionary Ladder … all the way to flowers

Willow Canyon ahead, what will we find?

On February 12—midwinter—we headed for “Willow Canyon” on the east side of the Laramie Basin, at 7200 feet, in the interior of the continent far from moderating marine influences. Yet it felt like spring … sunny, warm (40º F!), and no wind.

The prairie was brown except for occasional small green blades along the dirt road. Aside from limber pines and Rocky Mountain junipers, trees and shrubs were bare. But after entering the canyon we found much of interest. Emmie wore herself out in her usual futile pursuit of rabbits (enthusiasm far exceeds ability). I was more successful, finding everything from mosses to flowers in what appears to be just another small dry limestone canyon in the foothills of the Laramie Mountains. Starting low on the evolutionary ladder …

A walk up the Plant Evolutionary Ladder … all the way to flowers

Mosses—no seeds, no vascular tissue.

Mosses lined rock ledges in a shady alcove in the canyon wall. They were surprisingly lush, rich green and moist with recent snowmelt. I saw only gametophytes, with no sign of this year's sporophytes (the two phases of the moss life cycle). The mix of shade and light made photography difficult, so I just shot and hoped for the best.

Mosses reside low on the evolutionary ladder because they produce spores instead of seeds, and they have no vascular tissue—which explains why they’re short. Conducting water very far is difficult without plumbing.These moss clumps are aggregations of small individual stalks, gametophytes. There may be sex organs hidden at the tips of the gametophytes. If fertilized, female ones will grow into sporophytes (there's more in the elegant life cycle diagram mentioned earlier).

Clump of moss gametophytes, with a few dead sporophytes from last year.

An abundance of sporophytes; fairy for scale.

Lichens also thrived on the limestone ledges (orange and yellow mats above). I couldn’t place them on the plant evolutionary ladder as they’re not a single organism but three, in a beneficial partnership: an alga, a fungus and a yeast (the last is a recent discovery).I found a few ferns too, though not in the shady alcove as you might expect but rather on exposed rock faces. Tough little cliffbrakes with thickish dull green fronds seem to grow directly out of the rock. This is western cliffbrake (Pellaea occidentalis), which is calciphilic as well as xerophytic—limestone-loving as well as drought-tolerant. [See Plants on Rock for more about plants of Willow Canyon.]

Plant is about 2 in across.

Ferns are vascular plants so are considered more advanced than mosses, but they too produce spores, not seeds. Below is a seed-producer. However its seeds are naked, indicating we still haven't reached the top of the ladder.

My favorite gymnosperm (“naked seed”) in the canyon is this limber pine (Pinus flexilis). It’s a really small “tree” but its life history is impressive: a seed germinated in a dry shallow crack, grew into a seedling, and managed to keep growing with just a bit of moisture and debris each year! The annual rings must be microscopic. Any guesses as to age?

Nearing the top of the evolutionary ladder, I found an angiosperm (“enclosed seed”)—a flowering plant. And it was flowering! This may be the only native species blooming in the wild in the Laramie Basin right now (can’t think of any other possibilities).

Well … barely blooming. White hairs were just starting to emerge beyond the bud scales.

North American pussy willows (Salix discolor) bloom long before leafing out. I followed this one in 2015, after discovering flowers on February 26. Leaves didn’t show up until May. It's a male, and the only willow in the canyon. It thrives in an alcove shaded by junipers, with moss at its feet, next to a small waterfall that runs after heavy rains.

Willow Canyon pussy willow two years ago, on February 26.

The willow thrives thanks to great habitat. Water runs off the rock wall, and large junipers provide shade.

I easily walked to the head of the canyon (almost no snow!) and then returned by way of the rim, stopping for a few more views of the willow of Willow Canyon.

Eponymous willow peeks above the canyon rim (center of photo).

Of course, these plants pale in comparison to those being posted by bloggers from warmer zones, where gardens already are filled with color, or from moister climes where walls and nooks are lush with mosses and ferns. But this is southeast Wyoming. This time of year, even the most modest plants thrill us! At the same time, I hope this crazy weather doesn’t prompt more plants to grow and bloom … and then get zapped by repeated hard frosts.Coda
Though it felt like a spring day, winter made its presence known—best of all, in the form of ice art. Jack Frost produces terrific abstracts. Fortunately, several were still in place.