Our local species of fir is Alpine Fir (Picea lasiocarpa).  It is easily recognized among other evergreens by its taut, narrow habit; very vertical, branches very perpendicular, and looking quite stiff overall.  It is a cool, pale, bluey green overall, due to narrow white lines on the green needles.  Even though the needles grow out of their twigs in all directions, they all sweep upward.  The seed cones are held erect at the top of the tree.  My handbook says that in northern subalpine forests, cones are rare; the tree commonly reproduces asexually, by layering.  The trunk is straight and sturdy, with grey bark marked with horizontal bands of pitch blisters.  The tree prefers higher elevations, but will grow at lower elevations in places with cold air outflows.  It is an early post-glacial colonizer.  The pitch and bark are important medicines among interior tribes; and with one group its name means "medicine plant".  Boughs and bedding can be used as incense.

With all of the foregoing, I cannot help but think of a maiden aunt sitting up straight on a hard chair.  Minerva, The High Priestess, the new moon.  Youth, self-confidence, certainty.  Lofty thoughts, idealism, intellect, rationality, order.  One's fruits born of one's head.  Virgin reproduction.  A chaste bed.  Brighid the healer.

In the Celtic tree alphabet, Fir is Ailm, the sound A, and represents winter.  In one source, it represents honesty, truth, and straightforwardness--because it grows "straight and narrow".  In another, it speaks of taking a long view and seeing ahead, because it is a tall tree that can "see" into the distance.  I can agree with those interpretations!