Growth Process in Plants

Discuss growth processes in plants with special consideration of primary and secondary growth.

Growth in all plants is made possible by tissues called meristems.

Primary growth in plants - is the growth and length in roots and shoots.

Secondary growth - is growth in the thickness in the roots and shoots. Also it is produced by vascular cambium or cork cambium.

In order for plants to grow they need water and food and in order to get water and food they need meristems. Meristems produce the three basic tissues within the plant body: The procambium, produce the vascular tissue--the transport tissue xylem (water/nutrients) and phloem (food); ground meristems produces the ground tissue (the pith); and the protoderm produces the outer layer of tissue (the epidermis). These are considered the primary growth. They are responsible for the height and deep roots of the plant.

The secondary meristems regions, named so because the primary growth has to occur first, produce secondary growth. The vascular cambium which produces vascular tissue and cork cambium which produces bark which replaces the epidermis that the protoderm produces. They are responsible for the girth (width) of the plant.

Primary and secondary meristems divide differently. The primary meristems divide by stacking cells one on top of another (increasing length) and secondary meristems divide by stacking cells side-by-side (increasing girth). So to summarize a plant need both the primary and secondary growth in order to survive. Without the primary growth we'd have short, fat plants and without the secondary growth we'd have tall, thin, spindly plant.