Friday, December 25, 2015

Willow Pine Cone Galls

Snow crunched under my tires and bare trees whizzed by as I coasted down the hill on my fatbike. Cold air stung my cheeks, but my hands were warm in brand-new, homemade pogies that wrapped around my hands and bike handlebars like old-fashioned muffs. At the bottom of the hill, we passed through a wetland with dried grasses and shrubs frozen into the ice.

In the slightly drier ground next to the graveled forest road grew sparsely elegant clumps of willows. This was an unusual willow, though, that looked like it had hybridized with a pine tree. At the tip of most of the twigs perched a compact little “pine cone,” about the size and shape of a young, tightly-closed cone from a red pine tree.

These cones don’t hold any tree seeds, however. Instead, they harbor the “seeds” of a gall-midge called Rhabdophaga strobiloides. These are willow pine cone galls.

Like most galls, these began in early spring during the active-growth period for the plant and the egg-laying season for the midge. The adult midge laid an egg on the tip of the twig, right where a single, dunce-cap-like bud scale protected baby leaves. The larva hatched in early May and started burrowing into the willow stem. Some combination of the chewing action and saliva of the newly hatched larva triggered an increase in plant growth hormones. Cells grew bigger and more plentiful, but the stem did not extend. Instead, leaves once destined to flutter along a twig now layered together in the cone-like structures that caught my eye.

What’s fascinating is just how much the larva can control the plant. One study found that the twigs hosting a gall were larger in diameter than twigs with no gall—even if the twig did not have leaves. Bigger stems were correlated with bigger galls, and bigger galls were correlated with bigger larvae. This confirms the hypothesis that the larva somehow draws in the products of photosynthesis from other (probably un-galled) twigs in order to spur the growth of the gall, the hosting twig, and the larva itself.

This type of control may seem creepy, but it is frighteningly common in the world of parasites. Parasitic cordyceps fungi force ants to climb a plant and attach there before they die, providing a breezy platform for dispersal of the fungal spores. A brain parasite causes rats to be attracted to cats so that the parasite can complete its life cycle in a feline host. Horsehair worms drive zombie crickets to a watery death. In comparison, a tiny larva causing a plant to grow some extra tissue is pretty tame.
It is still amazing. All summer, the larva—eating stolen nutrients from the plant—grew within the protective walls of the gall. Late last May, the larva would have expanded enough that it needed to shed its skin, thus entering its second instar developmental stage. By late July, the growing larva shed its skin once more. Its next task before winter was to construct a cocoon and leave it open at the top.

So, there we are. Inside each of these cone-like galls by the side of the road is a little larva in a cocoon sleeping bag, steeling itself against the cold. The loosely packed structure of the gall may provide some insulation, but it isn’t nearly as good as my homemade pogies. The dormant larva doesn’t have the benefit of my fiery metabolism fueled by regular eating to keep it warm. In these situations, some creatures allow themselves to freeze. Wood frogs are one incredible example.

These larvae take a more daring route. By concentrating glycerol (once used in cars as antifreeze) in their bodies, the larvae can supercool their liquids down below the freezing point of water without them becoming solid. In extreme examples, larvae have safely supercooled to negative 76 degrees Fahrenheit. This requires a delicate balance. A disturbance in the system could cause the larvae to freeze and die instantly.

If a larva survives the winter, it will pupate inside the pre-formed cocoon early next April, and the adult gall-midge will squeeze out between the layers of the cone and fly away. 

Or not. Thirty-one other creatures might be illicit squatters in the loosely packed scales of the pine cone gall. These gall apartments are in such demand that during one study the scientist found 564 individual insects in just 23 galls. Most of the beetles, caterpillars, sawflies, and eggs of meadow grasshoppers are relatively harmless. The wasps, however, beat the gall-midges at their parasitic game by raising their wasp larva on the tender flesh of midge larva.

Who would have thought that the scales on those strange “pine cones” could be hiding such drama?

Photo by Dana at

Friday, December 18, 2015

The Elegant Simplicity of Moss

Slushy snow gave way to bare, squishy gravel as I crested the hill. The Yaktrax grippers on my running shoes instantly became annoying instead of essential with the surface change. Peering wistfully through the damp, brown woods, I could just make out the wide clearing of the Birkie ski trail. But my skis are still in the basement, waiting for real snow.

Brown, brown, brown. The forest appeared drab and dead. But as I looked up from the effort of the hill climb, vibrant greens glowed into view. A scattering of small boulders, probably dumped here by the glaciers, and later excavated when the road was built, hosted emerald carpets of life. Then, squish. One moment of distraction and my foot found a puddle.

It seems like distractions have plagued the climate talks in Paris, too. The negotiations seem hopeful, though, or at least better than nothing. Of course, even though this is the warmest fall on record across the globe, we can’t directly blame our warm weather on climate change. Climate is what you expect. Weather is what you get. They don’t very often match up perfectly in our day-to-day lives.

That’s why we have to be ready for anything. Moss is. It’s thriving today in the cold mist. Just like the balsam fir, the persistent, evergreen leaves of mosses are able to take advantage of favorable growing conditions in any season. Even when drought withdraws the water they need for growth, mosses are preparing for life in the future. Essential functions shut down and prepare for dormancy. Cell membranes shrink like a vacuum-sealed freezer bag. And, with amazing “forethought,” the mosses synthesize and store away the enzymes of cell repair that will manage the damage of desiccation. Like the Red Cross or FEMA, mosses like to have a stash of medical supplies ready to go. All of this groundwork pays off. In just 20 minutes, bone-dry moss can return to full vigor. This resilience of mosses is mostly due to their amazing ability to live thriftily and within their means.

Robin Wall Kimmerer, a botanist who recently won the Sigurd Olson Nature Writing Award for her book Braiding Sweetgrass, wrote an earlier book called Gathering Moss. In this ballad of love to the mosses, she writes, “They are the most simple of plants, and in their simplicity, elegant.”

Elegant indeed. Resourceful, one-cell-thick leaves allow water to soak in directly to where it’s required, without the need for constructing expensive distribution systems. Moss doesn’t even have roots. They don’t need to suck resources out of the ground. Their tiny rhizoids only serve to anchor them to the substrate. Never mind interior water, moss needs a film of rain, or melting snow, to cover the outside of the leaf, too, and act as a conduit for carbon dioxide to enter the leaf from the air.

“Like a jealous lover,” writes Robin, “the moss has ways to heighten the attachments of water to itself and invites it to linger, just a little longer.” Living in tightly packed clumps improves moss’s water-holding efficiency. So does arranging their branches and leaves so that each space is the perfect size to trap a water droplet using capillary action. Leaf surfaces are textured or pleated or sculpted into hills and valleys to grab water. “This elegant design is a paragon of minimalism, enlisting the fundamental forces of nature, rather than trying to overcome them,” Robin observes.

Part of the moss’s minimalism is in their size. By staying small, mosses take advantage of the microclimate inside the boundary layer; which, “like a floating greenhouse hovering just above the rock surface,” traps water vapor, heat, and carbon dioxide. On a sunny, winter day, when the air is appropriately below freezing, the boundary layer often provides moss with liquid water. Waste gasses emitted from bacteria and fungi on rotting logs can increase the carbon dioxide in the boundary layer to 10 times the amount in the ambient atmosphere. Thus, moss ensures that it has access to a steady supply of raw materials for photosynthesis. 

Mosses are confined to this boundary layer. They thrive within it and cannot survive beyond it. In similar fashion, humans are restricted to a thin zone of habitable conditions that surrounds our Earth. We aren’t as good as the mosses at living within our means, though.

Robin, with her Potawatomi heritage, talks about stories from the oldest days, “when all beings shared a common language.” Not anymore. That language is forgotten. Instead, she says, “We must learn each other’s stories by looking, by watching each other’s way of living. [Mosses] have messages of consequence that need to be heard.” The big question is, both in Paris and in my mind, when will we listen?

For over 45 years, the Cable Natural History Museum has served to connect you to the Northwoods. Come visit us in Cable, WI! Our new exhibit: “Lake Alive!” opened May 1, 2015, and will remain open until March 2016.

Find us on the web at to learn more about our exhibits and programs. Discover us on Facebook, or at our blogspot,

Mosses have engineered elegant, water-holding characteristics into every aspect of their lives. They thrive within their means. We could learn much from them.
Photo by Emily Stone.

Friday, December 11, 2015

Calling All Artists! Announcing Natural Connections Cover Art and Illustration Contests with the Cable Natural History Museum!

Blogger Emily Stone is publishing a book of her Natural Connections articles as a fundraiser for youth programming at the Cable Natural History Museum. Since kids and artists in the community are often the inspiration for her articles, the Museum is conducting TWO art contests!
The first art contest is for kids to illustrate each of the 52+ chapters with a black-and-white line drawing based on an animal. 
The second is an contest for adults to illustrate the cover of the book. More details, and entry forms, can be found at:

Balsam fir

The quietness of the woods wrapped around me as I paused for a moment to listen. Under the combination of sunshine and fresh snow, the world gleamed. As my sphere of awareness widened, I realized that the woods weren’t as quiet as I’d first thought. My local flock of chickadees chattered and scolded in a birch tree. A woodpecker drummed nearby. And behind it all was the soft patter of twigs releasing their snow load and the plopping of the damp clumps onto the ground.

A clinging, wet snow had blanketed everything. While the snow-lined twigs of deciduous trees made artful black-and-white designs against the sky, it was a grove of small balsam firs—their pliable boughs drooping gracefully under the icy frosting—that perfected the winter scene.

Most of the year, balsam firs aren’t highly sought-after. Their wood is soft and brittle. It doesn’t hold nails. Pulpwood or light frame construction is about all they are good for.

It’s this time of year—with snow clinging to everything and holiday carols on the radio—that balsams prove their worth. Their conical shape, dark green color, and long-lasting needles make balsams ideal Christmas trees—whether or not they ever make it to your living room. Those characteristics also make them ideally adapted to winter. The graceful droop of their boughs is no accident; that’s an adaptation to living in areas with lots of snow. Better to bend than to break. The beautiful green of their needles means that they can extend their growing season to the max by being ready to photosynthesize whenever conditions are favorable.

A slight breeze through the treetops initiated a cascade of snow plops onto the trail—and down my neck. That got me hiking again. As I pushed aside a drooping branch, the movement released some of the fir’s wonderful perfume. I inhaled deeply and closed my eyes. The smell conjured up memories of a warm cup of tea on a cool morning in the Boundary Waters. Balsam fir tea is a lovely beverage, with several potential medicinal uses. I distinctly recall my ethnobotany professor, Ojibwe Elder Joe Rose, mentioning balsam fir as a laxative. If I remember right, he told us that when horses in the old logging camps would get constipated, they’d get a dose of balsam fir. And then, “Don’t stand behind them!” Joe warned. Luckily, it doesn’t seem to affect humans quite that abruptly.

One of balsam’s gentler benefits is its high levels of vitamin C. In fact, there’s a possibility that balsam was used to prevent and cure scurvy, instead of or in addition to northern white cedar, the tree we usually think of as Arbor Vitae.

After that fragrance- and memory-filled moment, my eyes opened just inches away from the twig. Two layers of needles spread out on either side. Each tiny sprig of green was flattened in cross-section. I knew from experience that if I picked off a single needle, I couldn’t make it roll between my fingers. Spruce needles, in contrast, are square in cross section, and spinning them between your thumb and forefinger is a nice way to fidget.

“Firs are flat and friendly,” was one of the first mnemonics I learned in botany class. As we gained confidence with technical terms, the professor added “and they have racing stripes like a fir-rari!” It’s true that if you turn a fir needle over, there are two light-colored stripes spanning its length. These are the stomata, which are the pores that allow carbon dioxide in, and oxygen and water vapor out.

I stepped back to admire the tree again. Just taller than me, it would be the perfect size to decorate for a home. To achieve this height might have taken it nine or ten years. But it could live 200 more, if all goes well. The tiny seed it grew from must have found plenty of water in the soil, and just enough light to grow. Balsams are one of the most shade-tolerant trees in the whole forest, and a seedling only needs 10 percent of full sunlight to get started and 50 percent of full sunlight to thrive.

While firs are synonymous with the holidays, they do lack one important decorative item: cones. That’s because the seed that produced this fir grew in a cone with deciduous scales, a cone that fell apart. If you are lucky enough to visit a fir grove in early fall, the mature trees will have clusters of beautiful, upright, purple cones perched near their crown.

Chickadees, nuthatches, squirrels, and porcupines eat the seeds. Moose, deer, and grouse eat the needles. Hungry red squirrels nip buds off the tips of twigs and throw the rest onto my early spring ski tracks. Balsam firs are important wildlife trees all year round.

The trail brought me home, red-cheeked and happy. On the front table sat my Charlie Brown Christmas tree—a scraggly little balsam fir that I felt no guilt about cutting. But when I closed my eyes and inhaled, it too became the “perfect” tree.

Sometimes it's nice to look at a familiar plant from a different perspective. Photo by Emily Stone.