Cross sections of Cedrus libani stem wood.
a Cambial zone (cz) during dormancy at the beginning of March with cambial initials and derivates, mature tracheids (m) of the previous year with thick secondary walls, and phloem (p) (b) Cambial zone during the growing season in June, enlarging cells (ec) (c) Wall thickening cells. The black arrow points at the intact protoplast of the cell (d) Enlarging cells which are not birefringent (black arrow) and wall thickening cells which are birefringent (red arrow) under polarized light (e) Mature cells with empty cell bodies and completely lignified secondary walls which appear intensely pink. f Resin ducts (rd) in the early wood during June. The bottom of the graphs are towards center of the stem. Scale bars: 50μm