Leaf Structure

Leaf Structure and Terminology

• Types of Leaves

  • Simple Leaf

    • Contains one continuous lamina (the flat part of the leaf).

  • Compound Leaf

    • The lamina is divided into smaller leaflets.

    • Terminology:

      • Rachis: the extension of the petiole to which the leaflets attach.

      • Pinnae: individual leaflets in a compound leaf.

• Compound Leaf Structures

  • Pinnate:

    • Leaflets grow on either side of a central rachis.

  • Bipinnate:

    • Further division of leaflets into smaller pinnules.

  • Palmate:

    • Leaflets radiate out from a single point, resembling a hand.

• Key Features of a Leaf

  • Petiole:

    • The stalk that attaches the leaf to the stem.

  • Leaf Tip:

    • The end of the leaf.

  • Margin:

    • The edge of the leaf.

  • Lamina (Leaf Blade):

    • The broad, flat part of the leaf.

  • Venation:

    • The arrangement of veins within the leaf, including various patterns.

  • Mid Rib:

    • The main vein that runs through the center of the leaf, often an extension of the petiole.

  • Axillary Bud:

    • Bud found at the junction between the stem and the leaf, often visible along with the leaf features.

• Note:

  • It's acceptable not to remember all terminology; focus on recognizing features and using descriptive words to identify them when studying plants. If uncertain, utilize resources to look up specific terms and characteristics as needed.