Stems and Leaves

Stem internal structure

A vascular bundle is a cord of xylem and phloem running through the stem (it’s thesame one that is found in the root)

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Stem Internal Structure

Inside each bundle, the phloem is often positioned facing the stem surface; the xylem is positioned facing the stem center.

Stem Internal Structure

The vascular bundle is surrounded by ground tissue.

Dermal tissue is on the outside of the stem.

LeafLeaves represent a large surface area that is exposed to sunlight and carbon dioxide for photosynthesis

Leaf Internal Structure

Leaf Internal Structure

The cuticle helps to prevent water loss.

Leaf Internal Structure

Mesophyll is parenchyma specialized for photosynthes

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Leaf Internal Structure

The palisade layer is exposed to direct sunlight

Cells in the lower part of the leaf are loosely arranged in the spongy layer (air sacs participate in gaseous exchange)

Leaf Internal Structure

Veins (vascular bundles of xylem and phloem) form a network for movement of water, solutes and photosynthetic products throughout the mesophyll

Leaf Internal Structure

Stomata are located mostly on the lower epidermis.

Leaf Internal Structure

Stomata are surrounded by two guard cells which open and close to regulate transpiration.

Leaf Internal Structure

Stomata are typically more abundant on the lower surface of the leaf, and sometimes only found there (except for floating aquatic plants like water lilies)