wpeD4.jpg (28436 bytes) This micrograph shows the beginning of secondary growth within the Bougainvillea stem. Note the cambial zone (CZ) immediately beneath the starch sheath (SS), and the central part of the stem which is occupied by primary bundles, within which secondary growth is occurring.

The internal vascular bundles are associated with conjunctive tissue. The primary bundle (encircled) has been formed by the vascular cambium.


Cells to the outside (exarch of) the phloem in this primary bundle are termed conjunctive tissue -- they remain meristematic and the cambial cells so formed, produce new secondary growth.

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