IF IT HAS WHITE BARK IT'S A BIRCH TREE..WELL,"IT AIN'T NECESSARILY SO..."

QUAKING ASPEN...

... WHITE BARK, BUT NOTE THE GNARLED, GRAY YOUNG TWIGS

PAPER BIRCH...

...WHITE BARK, AND  NOTE THE STRAIGHT, REDDISH YOUNG TWIGS...

...ALSO DORMANT  CATKINS...

....AND CHARACTERISTIC, BUT NOT ALWAYS PRESENT, EXFOLIATING PAPERY BARK

QUAKING ASPEN GROVE; BARK WHITE IN THE WINTER SUN

MIXED PAPER BIRCH AND ASPEN,  REDISH YOUNG BIRCH TWIGS STAND OUT

Sunday, 9:00 AM.  4 degrees F, wind N, light to moderate.  The sky is mostly overcast, with some fog over the channel and Madeline Island. The humidity is 74% and the barometer more-or-less steady, at 30.29".  We are just on the eastern edge of a polar air mass, which has temperatures in northern Minnesota in the -20's again. They can keep it.
   Paper birch, Betula papyrifera, is easy to pick out in the winter landscape because of its white bark!  Well, as the old song says, "It Ain't Necessarily So..."
   I have often been confused as to whether a grove of white-barked trees was paper birch or quaking aspen, Populous tremuloides, especially when viewed from a moving vehicle, or at a distance.  Particularly in bright winter sunlight, with white snow on the ground, trembling aspen can look just as white as paper birch.  And both species have characteristic black markings on the trunk, particularly under branch crotches.  As for the exfoliating bark of paper birch, it is not always present or not very obvious.  To add to the confusion, both may inhabit the same terrain, and often grow mixed together.  So, I have come to rely on other cues for more dependable winter identification, at least if I can't view the trees close up.
   I look to the young branches at the top of the trees.  The birch branches are straight and reddish in color, the trembling aspen are gray or grayish green and gnarled, or crooked.  Once one gets the hang of it it is pretty easy to see the difference, even at a distance and even if the trees are growing mixed together.  Closer up, the birch trees have pendulous dormant winter catkins that can be quite obvious. Birch trees often shed seed during the winter, and the minute, triangular, wafer-like seeds  may be found on the snow beneath the trees.
   Of course, paper birch are so-called because of their exfoliating, papery bark.  The problem is, that characteristic is not always present.  Of course, when it is, the identification is certain.  But if not,  "It Ain't Necessarily So,,,"