Stems are composed of nodes and internodes and serve several functions. They support leaves through an internal structure and turgor pressure. Stems also produce carbohydrates through photosynthesis, store materials like starch and water, and transport water and nutrients between roots and leaves via their vascular system.

2.  A stem is a collection of integrated
tissues arranged as nodes and
internodes.
 Nodes are regions where leaves attach
to the stem.
 Internodes are the parts of the stem
inbetween the nodes.

3.  Stems support the leaves. Leaves are
supported by a stem’s internal skeleton
of collenchyma and schlerenchyma.
 turgor pressure in stems provides a
hydrostatic skeleton that supports the
young plant.

4.  Stems produce the carbohydrates. Stems
of some plants are photosynthetic.
 Although it is insignificant compared to
those produced by the leaves, in plants
such as cacti it accounts for most of the
plants CO2 fixation.

5.  Stems store materials.
 Parenchyma cells in stems store a large
amount of starch and water.
 For example, water accounts for as
much as 98% of weight in cacti syems.

6.  Stems transport water and solutes
between roots & leaves. Stems link leaves
with the water and dissolved nutrients of
the soil.
 The vascular sytems of stems maintains
an aquatic environment in leaves and
transports sugars and other solutes
between leaves and roots.