Serjania stem


In this cross section, one can clearly see that this stem has a well-developed periderm (Per) beneath which is a broad band of sclerenchymatous phloem fibres (Sc). At least three bands of phloem are evident in this section each of which is associated with darkly-staining tanniniferous and or mucilaginous cells. Beneath the secondary phloem (2P), is a narrow cambial zone (CZ) separates the cambium from the secondary xylem (2X). The large xylem vessels within the secondary  are solitary, occurring in  files, and surrounded by bands of lignified fibres as well as lignified parenchymatic elements. The parenchyma within the secondary xylem occurs in narrow concentric zones or bands, varying from narrow strands, to completely encircling the solitary large-diameter secondary xylem vessels. This is described as aliform-confluent paratracheal parenchyma.


Apotracheal means parenchyma bands that are mainly independent of the vessels;

Paratracheal means parenchyma associated with vessels.

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