[IB Plant Science at GHS]

External Structure of the Stem

of a Typical Dicotyledonous Plant


Stem Function:

a. Support of main body of plant & leaves.

b. Conduct water & food.

c. Photosynthesis in new green stems.

Leaf Scar: Heart-shaped scar on twig where last years leaf grew.

Node: Growth region on stem. Region around bud or leaf stem.

Bundle Scar: Tiny bumps in leaf scar where veins enter the leaf from the stem.

Terminal Bud: Bud on end of a branch, where all of next years length (of branch) is added.

Lateral Bud: Small buds along length of branch that develop into leaves, lateral branches, or flowers.

Apical Dominance: The terminal bud dominates all other lateral buds by giving off hormones. If the terminal bud is cut off, the lateral buds will grow longer.

Girdling: Cutting of bark around tree into cambium layer kills tree (no sap to roots!).

[External Features of the Leaf]

Long & Slichter