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Secondary Growth-2

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Diagrams contrasting Primary and Secondary Growth: Note the increase in width that accompanies Secondary Growth.

Significant amounts of Secondary Phloem are produced by woody species.

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Cross-sections of Tilia stems: Note the thick layer of Secondary Phloem that surrounds the Secondary Xylem.		 TiliaStemXS1YrCropHue250Lac.jpg (152106 bytes)
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The Secondary Phloem of Tilia contains a lot of Fibers. These appear bright under polarized light because they have extremely thick cell walls.

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Secondary Phloem is produced by the Vascular Cambium which lies between the Secondary Phloem and Secondary Xylem

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The Secondary Phloem of Tilia contains a lot of Fibers. These have stained red due to the presence of Lignin. The Fibers protect the thin-walled conducting cells & allows the phloem to work over several years without being crushed.

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Secondary Phloem Fibers have been used by Hawaiians and others to make cloth like kapa (wauke) as well as cordage (hau).
The diagram to the right compares a drawing of Tilia with a photograph of hau.

The hau image was taken with polarized light. the Phloem Fibers and Xylem are bright orange/red.

Secondary Phloem is known as the Inner Bark.

Wood is Secondary Xylem.

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