A weathered old northern red oak (Quercus rubra) is home to many species of birds and other animals.

A tree’s beauty is easily noticed in three seasons: Spring’s first green haze of buds; summer’s rustling crown of leaves; and autumn’s smoldering colors. Winter uncovers a different kind of beauty: that of bark, interesting shapes, animal shelters and open sky — the guts of things not often seen.

A small stand of northern red oak, at our cabin along the Snake River in Pine County, MN, includes a tree that was sheared off in a summer windstorm two decades ago. Neighboring branches hide the jagged top most of the year, but in winter the scarred wood’s polished grain and shape are revealed, along with hidden nesting cavities. Squirrels, great-crested flycatchers, red-bellied woodpeckers and most recently, pileated woodpeckers have nested and raised their young in this red oak.

Crabapple trees (Malus) provide food for many birds and add winter color.

Crabapple trees, especially those with long-lasting fruit, add warm crimson to the stark black and white landscape. Their small shapes and curving branches remind me of bonsai trees. By late spring, most of the plump fruit will be consumed by cedar waxwings and robins.

The bark of river birch (Betula nigra) is multicolored and has a shredded texture.

Bark patterns and colors are more pronounced in winter with fewer distractions from the rest of the plant world. One of my favorites is the papery bark of the river birch. The colors range from soft brown to salmon, pink and ivory. The bark shreds and flutters in the wind. Paper birch bark (Betula papyrifera) is pretty too, especially at sunrise and sunset when low rays add blush to the tips of twigs and branches.

White spruce (Picea glauca) and other evergreens shelter many creatures.

The white spruce has grayish-red bark with a rough mosaic-like texture. Its evergreen branches shelter cardinals, kinglets, juncos and chickadees. At the end of winter, new burgundy cones appear, like tiny ornaments, on the tips of branches.

New cones form on a white spruce.

Winter trees reveal the hidden face of nature — textures, hues, patterns weathered and worn — and more open sky to view the moon, stars and urban sunsets; beauty to the eye that looks carefully. What do you see?

Winter sunset over Saint Paul, MN, on Feb. 22, 2017.