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Annual rings in pinewood (transverse section)

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1  annual ring
3  false growth ring
4  resin ducts
2  growth rings

English name: Pine
Scientific name: Pinus sp.
Familia: Pinaceae
Classis: Coniferopsida
Phylum: Gymnospermae
Regnum: Plantae
Annual rings in this cross-section of the stem appear clearly because of the difference in “density” between spring wood and summer wood. Spring wood has a lighter color than summer wood since tracheids formed in spring have a large diameter (seen radially) and a thinner cell wall. The formation of cells with a larger lumen (opening) and a thinner cell wall is an adaptation that enables sufficient supply of water for the tree. (Remark: the cell wall in this specimen have been stained with a red dye to emphasize contrast. However, also unstained material shows a distinct transition between spring and summer wood).
View a detail of a cross-section

last modified: 5 Jun 2014