Two Trees and a Rock on a Trail

First, the Weather Report.

It's time for a final report about the trees I followed this year. But they haven't changed since last month, and it's cold and wicked windy. I'd rather think about that nice October day when I met two trees and a rock on the trail to Lamoille Lake, in the Ruby Mountains in northeast Nevada.

Rock huggers.

I imagined these gnarled old trees as seedlings emerging above ground in a protected spot next to the giant boulder. For years they grew taller from apical buds, and wider by adding new vascular tissue (plant nerds—see diagram further on). They were symmetrical saplings until they bumped into the rock. But they kept growing anyway, taller and wider ... except where they couldn't.

Limber pines, Pinus flexilis (named for tough flexible branchlets).

Trees grow taller at the top, not from the base (a common misconception).

This is my contribution to the monthly gathering of Tree Followers kindly hosted by The Squirrel Basket. Consider joining us for some low-key good times (more here). Now I need to go find another tree!

Visiting an Old Tree Friend

Five years ago, I came across a blog post about a young sycamore (maple in the USA) emerging from a street drain! It was discovered by Lucy Corrander, a member of a loose-knit group of tree-followers. Lucy informally “led” the group by periodically listing recent tree-following posts. Anticipating tree camaraderie, I decided to follow a limber pine (Pinus flexilis). Like Lucy’s sycamore, it started life in a dark out-of-the-way place—a five-foot-deep crevice in a granite outcrop. That must have been many hundreds of years ago, judging by its situation and size.

Sycamore (maple) emerging from its dark wet home in 2012. Lucy reports it’s still growing there!

Limber pine emerging from a granite crevice near Blair Picnic Area in the southern Laramie Mountains.

There were enough tree-followers that Lucy organized monthly gatherings facilitated by Mister Linky, now hosted by The Squirrelbasket. In the years since, I’ve followed a cottonwood, a willow and a serviceberry—always interesting and fun.

Consider joining us!

Though there’s no obligation, I’ve mostly been diligent in my monthly reporting … until this year. That’s because I decided to follow a Powell palmetto, which has been extinct for millions of years. The beautiful fossilized frond in a hallway in the Geology building was irresistible. But I soon ran out of palm and fossil stories, and work and weather have kept me from visiting its lithified habitat on the other side of Wyoming. In the meantime, I’ve wandered from tree to tree. This month I visited my old friend, the limber pine.

From the approach, it hardly looks impressive—half dead and leaning severely. But up close, it’s spectacular! What character!! I like to look at the big scarred tree leaning against the rock and imagine its early years, back when it was a slender youngster living down where the sun rarely shone and snow melted late each spring. It couldn’t have grown more than a minuscule amount each year!

When the sapling reached the rim of the crevice, did it experience a growth spurt? Maybe relatively-speaking. The growing season is short (8000 feet elevation), though being evergreen, a limber pine will photosynthesize in winter if there's a “warm” day.

Surely the Wyoming wind blew the supple young tree against the rock on a regular basis. Maybe that’s why there’s a large bark-less scar where it meets the crevice rim …

… or maybe not. On the other side, the bark joins tightly with the granite.

In addition to the scar at the rim, strips bare of bark wind up the trunk. Several large roots are exposed and vulnerable, if not already dead. A good portion of the crown is dead. But the remaining live branches are healthy, their branchlets thick with needles.

The limber pine looks healthiest viewed from above.

As for change … there were some obvious ones. Several minor branches covered in green needles five years ago are now brown.

Five years ago my field assistant was Sparky, who was always happy to pose when I pulled out the camera. Now Spark is gone, replaced by Emmie, who still hasn’t figured out what a camera’s for, even after three years of fieldwork.

And those aches and pains I felt scrambling up to visit the tree this year, were they around five years ago? Hmmm. You know, I don’t remember …

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 …

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.

Jack can turn even the most mundane object into a thing of beauty … like a mud puddle:

Thanks to Beth of Plant Postings for the inspiration to look for plants on rocks in midwinter: It's Only a Rock Wall ... Or Is It?

Autumn Tree Strategies II

Note leaning limber pine emerging from large fissure in granite outcrop, near center of lower left quarter of photo (click on image for better view, or see photo at end of post).

I’m following two trees.  One is a weeping birch that grows in my yard, subject of a recent post.  All summer long its leaves collected sunshine and carbon dioxide, cranking out carbohydrates to keep the birch healthy and growing.  Then about a month ago, after turning a pretty gold, they died and fell off.  Just as well ... thin flimsy birch leaves would freeze in winter.  Now the tree is dormant.

Weeping birch, Betula pendula, native to Europe and Asia.

My other tree is a limber pine (Pinus flexilis) in the Laramie Mountains east of town.  It grows out of a deep fissure in a large outcrop of 1.4-billion-year-old Sherman granite.  I went up there just last week to see what it’s doing.  These are the perks of tree-following, going to nice places and seeing and learning things I probably wouldn’t otherwise.

All the quaking aspen along the trail were bare.  They got rid of their worthless leaves over a month ago.

Below, approaching the limber pine.

This tree appeals to me because of where it grows, and because it’s big, rugged, gnarled and scarred.  Unfortunately, the location makes it difficult to photograph.  The photo below was shot from the best place to see most of it.  I’m always impressed by the large half-dead tree growing out of the rocks.

The tree got its start in a fissure 4-5 feet deep.  How did it survive down there in the shade for so long?  Did it take off once it was tall enough to bask in sunshine?

Some of the larger branches are dead and others are missing bark, but no bother.  The pine keeps growing, a little bit each year.

Below is the tree from above.  I walked along the top of a large granite fin, peeking over the edge until I saw it.

It's November, so what has the limber pine been doing to get ready for winter?  Not much it appears.  The long flexible branchlets still have green needles and in fact they will all winter, for limber pines are evergreen.

This is one of several common but confusing tree terms:

Evergreen -- with leaves year-round; most conifers and many broadleaved trees.

Deciduous -- leafless part of the year when conditions are inhospitable to growth; a few conifers and many broadleaved trees.

Conifers -- Gymnosperms, with naked exposed seeds frequently in cones (no flowers); e.g. pine, spruce, Douglas fir, redwood.  Leaves usually needle-shaped or scale-like, but sometimes broad.  A more primitive group evolutionarily.  Also called “softwoods”.

Broadleaved trees -- Angiosperms, with developing seeds housed inside ovaries in flowers; e.g. magnolia, maple, eucalyptus, beech, weeping birch.  Leaves usually broader than needles but not always.  A more advanced group evolutionarily.  Also called “hardwoods”.

Below, a compact and durable conifer needle, followed by part of a thin flimsy but more productive broad leaf.  Source (modified).  Photosynthesis takes place in the mesophyll.

Fortunately the limber pine has needles instead of broad leaves, a much better choice for winter.  They shed snow more readily and have less sap that could freeze.  They lose less water (big issue in winter) because the ratio of surface area to volume is smaller.  Their thick epidermis covered with a waxy cuticle also protects from desiccation.  These are all very good adaptations but ... they aren’t enough for frigid winters in the mountains.

Limber pine needles are five to a cluster.

Turns out the limber pine has been getting ready for winter, for some time now.  It went through a pre-dormancy stage as it does every year.  Resting buds were formed, growth stopped, metabolism slowed, and various chemical changes took place -- for example increasing salts and sugars in cells to lower the freezing temperature.  Now it can rest through the winter.

Dormancy ends in spring after a sufficiently long period of sufficiently cold weather.  It’s then that the benefit of keeping needles all winter becomes apparent.  The limber pine won’t have to grow a whole new set of leaves, it can get to work photosynthesizing and making tree food right away!

Some conifers even photosynthesize at low rates during warm spells in winter, another advantage of keeping needles on.  Can a limber pine do this?  I don’t know.

I'm following a tree ... are you?

This is the second post in a short series about autumn tree strategies.

Sources  (in addition to links in post)

Havranek, WM and Tranquillini, W.  1995.  Physiological processes during winter dormancy in Smith, WK and Hinckley, TM, eds.  Ecophysiology of coniferous forests.  Academic Press.

Thomas, P.  2000.  Trees:  their natural history.  Cambridge University Press.