Unformatted text preview: The phloem rays often connect to xylem rays. Since the phloem consists of thin-walled sieve tubes and their companion cells, the older phloem gets crushed and compacted with the lateral expansion of the stem. New cork cambium tissue is formed from non-functioning phloem parenchyma and forms new periderm layers to separate older phloem from newer phloem. The older phloem and periderm layers are eventually sloughed off. Dilated phloem rays Phloem Older Phloem and Cork...
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- Fall '09
- Plant anatomy, Vascular cambium, phloem Secondary phloem, Phloem Secondary