Cross Section
of Pine Wood 400x Detail of a Growth RingCross Section
of Pine Wood 400x Detail of a Growth RingWood produced in late summer has small cells with thick walls. Spring wood has large cells with thin walls. Where these meet represents where the vascular cambium was dormant during one winter.
Based on this information you should be able to tell that the center of this tree is up.
Note the three xylem rays.