Do Plants have a Vascular System?

Yes, you read that correctly: vascular plants have their own version of a circulatory system. Understanding this system is essential for a gardener.

The Basics

Plants have a complex network of tissues that transport water, nutrients, and other substances through the plant. The system is consists of xylem and phloem.

  • Xylem transports water from the roots to the leaves of the plant. Unlike animals, plants don’t have a heart to pump water up to the leaves. While some plants are capable of a pumping action, those that can’t rely on the cohesive properties of water to move it through the plant. When water evaporates from the leaf (i.e., transpiration), it creates negative pressure that pulls more water upward from the roots (the Cohesion-Tension (C-T) mechanism).
  • Phloem moves carbohydrates created from photosynthesis, hormones, and sap both up and down the plant. Read more about phloem here.

These tissues are arranged differently across plant species. Some trees are a subcategory of flowering plants called dicots (a.k.a. eudicots). Read more about dicots here. In dicots, these tissues form in separate bands. Phloem is on the outside, and xylem is on the inside. Have you ever nicked a tree with weed wacker or mower deck and the tree died? The issue may have been caused by girdling, a.k.a., ring barking, which damages the phloem of the plant and prevents the tree from moving nutrients within the plant. While plants can compartmentalize damage, they cannot “heal” like animals. Once the damage is done, the plant cannot repair and replace vascular tissue. If the damage is significant enough to be detrimental to the transport of water and/or nutrients, which depending on the plant species may be just under the bark, the plant will die. 

Learn more here.

See the phloem in red in this cross section, the xylem is the tissue underneath the phloem in this plant, or the inner bark. Illustrations, PowerPoints or photos by Edward F. Gilman, Professor, Environmental Horticulture Department, IFAS, University of Florida.

Beyond the Basics

Using Herbicides

Always fully read the entire label of any herbicide you plant to use. It is required by law to follow the instructions, dosage, and restrictions specified on the herbicide’s label.

Type of Herbicide

Systemic herbicides are designed to be absorbed by the plant, once the chemical infiltrates the vascular system, it can affect the growth process and lead to the death of the plant. This is not a contact herbicide, this process takes more time. So if you don’t see immediate change, do not reapply.

Active Growth

These chemicals are typically applied when the plant is actively growing, meaning when it is actively translocating water and nutrients within itself, which is essential for the success of these types of herbicides.

Environmental Conditions

It is also important to keep an eye on the weather when using these chemicals. Cold and dry conditions hinder the metabolic activity of some plants, which may slow down the water and nutrient movement, and ultimately, the herbicide. On the other hand, make sure you plan around rain. If the herbicide washes away before the plant can absorb it, it will not be effective. This can also lead to harmful runoff, which can cause unwanted consequences. Herbicides are subject to application restrictions, such as buffer zones around water bodies, to prevent environmental contamination.

Read more about herbicides here.

Pruning and Grafting
  • Pruning: It is important to keep in mind that plants do not heal. When you prune a plant, you are damaging it while encouraging new growth at the same time. Making the right cuts with the proper sterilized materials is important. You risk damaging important vascular tissue that could stunt the plant’s ability to transport water or nutrients and infecting the plant with improper techniques and tools. Read more about pruning here.
  • Grafting: This is a technique that combines the xylem and phloem of two different plant parts. To be successful, the understanding of how these vascular tissues align is crucial. Read more about vegetable grafting and fruit tree grafting.
Landscape Design

Selecting the right plant for the desired location is imperative, think about the water and light requirements of the plant. This is principle #1 of the Florida-Friendly Landscaping™ Program. Plants should be chosen based on how well their needs align with the environment where they will be planted. Additionally, trees that are classified as dicots tend to grow tall and wide due to the expansion of their vascular system and root structure. The xylem (wood) and phloem (inner bark) continue to grow with the tree (this also applies to the roots). So you may not want to plant an oak tree right next to the foundation of your home.

Have a question?

If you have any questions about gardening in Central Florida, please contact UF/IFAS Extension Pasco County at 352-518-0156. For more information on UF/IFAS Extension Pasco County Community Gardens, and how you can join one, visit http://sfyl.ifas.ufl.edu/pasco/. Supervising agent: Dr. Whitney Elmore.

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Julia Sirchia, Program Assistant at UF/IFAS Extension Pasco County
Posted: January 21, 2025


Category: Florida-Friendly Landscaping, Home Landscapes, Horticulture, UF/IFAS Extension
Tags: #RightPlantRightPlace, Botany, Dicot, Efficient Irrigation, Full Sun, Herbicide, Herbicides, Monocot, Phloem, Photosynthesis, Plant Vascular System, Sunlight, Water, Xylem


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