Type of Roots: Each root system below is defined or dominated by one root type, hence their names. Some tree species are more likely to have one root system than another, but keep in mind that site conditions are just as important. Most urban trees have lateral root systems due to shallow topsoil layers and frequent, shallow irrigation. Let’s discuss about type of roots in details.

Type of Roots

Taproot System

• Dominated By: Tap root.
• Stability: Tap root systems are very stable, but extremely rare in mature trees.
• Common Species: Some oaks and pines, hickory, sweet gum, tupelo, walnut.

Lateral Root System

• Dominated By: Lateral roots.
• Stability: Lateral root systems obtain their stability from tree weight and root spread. These root systems don’t necessarily have a lot of root mass, but because the roots are so widespread, the tree can be supported without investing so much in roots. About 80% of tree species and most urban trees have lateral root systems.
• Common Species: Ash, birch, cottonwood, hackberry, maple.

Heart (aka Oblique) Root System

• Dominated By: Heart (aka oblique) roots.
• Stability: Heart root systems obtain their stability from root ball weight and soil resistance. The tree is held up by the weight of its root ball counteracting the weight of its aboveground parts and the strength of the soil around it. Heart root systems are prone to failure in wet soils. Once the soil is wet, wind and gravity can make the tree rotate in the ground, much like a ball-and-socket joint.
• Common Species: Honey locust, red oak, sycamore. More common in Mediterranean and arid climates.

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By Team Learning Mantras