Stem Structures, Functions, and Growth

ray

a continuous line of parenchyma cells running from the secondary xylem to the secondary phloem

vascular cambium

a single layer of meristem tissue between the xylem and the phloem that produces the secondary xylem (wood) and the secondary phloem (inner bark)

meristem

a specialized area where plant growth takes place and where cells divide and differentiate

stem

an organ that serves as the main stalk of a plant or that supports a plant part, such as a leaf, a flower, or fruit

apical meristem

dividing tissue found at the end of a stem and at the tip of a root

bud primordia

embryonic buds

leaf primordia

embryonic leaves

cork cambium

lateral meristem that produces cork cells and cork parenchyma

periderm

secondary tissue consisting of cork-producing tissue, the cork cells, cork parenchyma, and remnants of primary tissues that become the outer bark

heartwood

the darker and older inner wood of a tree

primary growth

the increase in the length of a plant; it occurs in an area called the apical meristem

secondary growth

the increase in the width of a stem due to activity in the lateral meristem, which is tissue found on the sides of stems and roots

node

the location where a leaf attaches to the stem

internode

the space between nodes

sapwood

the younger and lighter-colored wood circling the heartwood of a tree

pith

tissue composed of large, thin-walled parenchyma cells that makes up the core of a dicot stem

cortex

tissue composed of large, thin-walled parenchyma cells, collenchyma cells, and sclerenchyma cells found to the inside the epidermis and on the outside of the vascular tissues