FACT
Confocal
microscopy is an
advanced kind of
microscopy which
allows us to stain
various cell types or
structures with
different colours,
and visualise them
in 3D, using special
lasers and computer
software.with the xylem and phloem tissues of the root. Its functions are the formation of lateral roots
and the formation of a lateral meristem to allow secondary growth (thickening) to occur in
the root.
The phloemtissue is responsible for transporting food from the leaves of the plant to the
cells of the root. Thecambiumseparates the xylem and phloem tissues from each other.
This is the area where secondary growth of xylem and phloem tissues occur.Xylemtissue is
responsible for transporting water and dissolved mineral salts to the xylem tissue of the stem
and leaves. These cells are strengthened with lignin for support. The pits in the cell walls
allow for the lateral movement of water. Figure 6.9 shows stained root tissues visualised by
confocal microscopy. It shows the internal structure of root cells, including the epidermis,
cortex, endodermis and pericycle.
Figure 6.9: Stained root tissues as visualised by confocal microscopy. Colour key: brown, epidermis;
red, cortex; blue, endodermis; green, pericycle.
Stem anatomy DUMMY
Stems usually grow above the soil surface and towards the light from the sun. Depending
on the hardness of the stem, we can distinguish betweenherbaceousstems, which are leafy
non-woody structures, andwoodystems. Woody stems are harder than herbaceous stems.
Stems have four main functions.
- Support for the plantas it holds leaves, flowers and fruits upright above the ground.
Stems keep the leaves in the light and provide a place for the plant to keep its flowers
and fruits. - Transportof fluids between roots and shoots in the xylem and phloem.
- Storageof nutrients.
- Production of new living tissue: stems contain meristematic tissue which generates
new tissue.
The main stem develops from theplumule of the embryoand the lateral branches develop
from the buds. Nodes and internodes are regions found on the stem. Nodes are the regions
from which leaves and lateral branches develop, and the regions between nodes are known
as internodes (shown in Figure 6.10).Stomata, or pores, can be found in stems of younger
plants. We will subsequently discuss the tissues present in the dicot stem. The trunk of a
tree (shown in Figure 6.11) is the stem.
Chapter 6. Support and transport systems in plants 163