RACHIS
Secondary Growth
Secondary Growth
Secondary growth in the rachis is very
similar to that of secondary growth in shoots.
Rachis XS
The secondary vascular tissues of the
rachis are similar to that of the secondary
shoot, as well. The rachis in the image at left has just begun to
undergo secondary growth. The green bracket indicates the area of primary
phloem. The yellow bracket indicates the area of primary xylem. In the
area between these two brackets, the vascular cambium has begun to produce
secondary phloem and secondary xylem. The red arrow points to an area
of vascular cambium.
Rachis XS
The image at left shows an excellent depiction of a sieve plate between two sieve tube members in the secondary phloem of the rachis. Callose, indicated by the blue thickenings, is surrounding the pores. A polysaccharide, callose develops quickly in response to injury.
Rachis LS
