Vascular Bundles

Vascular bundles are similar to the human circulatory system. They are the visible veins seen on the back of leaves, but vascular bundles also make up the majority of a plant’s structure.

Deciduous leaves have veins that are easy to see

Parts of the vascular bundle

Vascular bundles are made up of the xylem and the phloem. The xylem carries water and dissolved minerals up from the soil, through the roots, to stems and leaves. The phloem carries dissolved food, especially sugars, down, from the leaves, to storage tissues in the stems and roots.

Vascular bundle - xylem carrying water and minerals up and the phloem carrying products of photosynthesis down into the plant. (Nefronus) CC BY-SA 4.0

There are various arrangements of vascular bundles, depending upon the type of plant. ​

Dicot vascular bundles are arranged in a circle, while monocot veins are scattered (CNX OpenStax) CC BY 4.0

Diseases of the vascular system

The flow of water and nutrients is critical to a plant’s health. Many pests and diseases take advantage of this fact. Damage to the vascular bundle can cause wilting, chlorosis, or even death. Common pests and diseases of vascular bundles include:

• Fusarium wilt (Fusarium oxysporum f. sp. chrysanthemi and f. sp. tracheiphilum)
• Verticillium wilt (Verticillium dahliae)
• Hollow stem (Erwinia carotovora)

Fun with the vascular system

You're never too old to enjoy this one and your kids are sure to enjoy it - put some celery stalks in a cup of water with food coloring and watch the dye move through the stalk's vascular system. Try it with other plants and show us pictures!  ​