According to the calendar, winter began with the winter solstice of Dec. 21. It will end at the time of the vernal equinox March 21.

As we travel through these days of the cold season, we might note that the first week of February is halfway. At this time, we are midway through winter; some Northlanders are looking beyond the second half. Noting this middle time I believe is the actual reason for the Groundhog Day story to be Feb. 2.

I don't expect to see any groundhogs (woodchucks) as I walk in the mid-winter woods. As expected, the temperature is chilly and we have an ample snowpack on the ground.

Woodpeckers drill into trees for a meal; a few chickadees and nuthatches flutter about and overhead are the usual ravens and crows. Silent in early winter, I now hear barred owls calling during nights. Plenty of dear tracks and signs are on the snow. Squirrels have been visiting their caches and I find trails of mice and shrews among the fallen branches. And the coyotes leave tracks telling of their breeding season.

But as I pause to look around, I see more.

Many of the trees hold green, blue-green, gray and even yellow patches of lichens. These hardy growths deal with winter, cold and dry, right out in the open. Also on the trees are small growths of mosses and their cousins: liverworts. Both are very shriveled and dry now, but still alive.

But the largest growths on the trees at this time are the shelf, or bracket fungi.

The term "shelf fungus" is a collective name of the various kinds of fungi, related to mushrooms, which grow out from the bark of trees at a right angle. Under the bark, often penetrating deep into the wood of the tree, are the mycelia of these fungi.

Mycelia are like threads and gather the needed nutrition and moisture for the fungi to survive. The part that we see sticking out from the trees, like a shelf, is the reproductive part. Like mushrooms, they produce spores within tiny openings on the undersides.

Unlike mushrooms, these reproductive parts of the shelf fungi are very robust, almost like the wood that it grows on. Most of us have seen enough mushrooms to note that they are rather soft, easy to break, smash or bite into.

And the typical mushrooms last only a few days to a week. Shelf fungi are perennial and often years old. The flesh of these strange fungi is solid and dry.

Though there are several kinds in the woods, I see three that stand out of note. On birch trees, grows a whitish-gray one that has many pores (holes) underneath. And so, it is called birch polypore (piptoporus).

Another gray one is about the same size and shape of a horse's hoof and is known as horse-hoof fungus (fomes).

But the largest ones that I find are brown with concentric growth rings - not to be confused with annual rings - on the top, white below. Because the white underside can be written or drawn upon, this fungus is often called artist fungus (gamoderma). It is not uncommon to see these fungi complete with excellent drawings in museums or novelty shops.

They don't look like much now, just bland solid structures on the sides of trees, but these fungi will survive the winter and live for years to come, growing larger each year.

Now, in mid-winter, they are prepared for the coming growth time.

Retired teacher Larry Weber, a Barnum resident, is the author of several books, including "Butterflies of the North Woods," "Spiders of the North Woods," "Webwood" and "In a Patch of Goldenrods." Contact him ℅ Katie Rohman at krohman@duluthnews.com.