Leaf Surface

Leaf Surface Overview

• Purpose of Leaf Surface

  • Absorbs and releases gases (CO2, O2)

  • Conserves water; release of water is necessary for water transport through xylem

  • Balances water exchange in the plant to prevent dehydration

• Mechanism of Water Control

  • Plants must not release more water than they absorb

  • Special structures exist on leaf surfaces to manage water loss

  • Adaptations vary based on environment:

    • Plants in wet areas handle water differently than those in arid regions

• Surface Features of Leaves

  • Coatings that aid in water conservation:

    • Cuticle: Often a waxy surface to prevent water loss

    • Oil glands: Visible in some plants (e.g., Eucalyptus, St. John’s Wort)

    • Can often be seen under light or felt by hand

• Examples of Leaf Surface Features

  • St. John's Wort: Clearly visible oil glands when backlit

  • Eucalyptus: Commonly exhibits oil glands that can be touched and smelled for identification

• Leaf Surface Descriptions

  • Glabrous: Smooth surface without hairs

  • Glaucous: Waxy texture with a bluish appearance, common in Australian natives (e.g., Eucalypts)

    • Touch reveals blue wax that can rub off

  • Pubescent: Slightly hairy or fuzzy texture; not coarse like 'hairy'

  • Vestiture: The general term for leaf surface texture

• Visual Identification

  • Glaucous surfaces often show where plants have rubbed against each other causing wax to wear off

  • Pubescent leaves exhibit a distinct fuzzy texture; e.g., Verbascum thapsis is an example of a plant with such features