En Español

Q. Who is Mr. Smarty Plants?

A: There are those who suspect Wildflower Center volunteers are the culpable and capable culprits. Yet, others think staff members play some, albeit small, role. You can torture us with your plant questions, but we will never reveal the Green Guru's secret identity.

Help us grow by giving to the Plant Database Fund or by becoming a member

Did you know you can access the Native Plant Information Network with your web-enabled smartphone?


Ask Mr. Smarty Plants

Ask Mr. Smarty Plants is a free service provided by the staff and volunteers at the Lady Bird Johnson Wildflower Center.

Search Smarty Plants
See a list of all Smarty Plants questions

Please forgive us, but Mr. Smarty Plants has been overwhelmed by a flood of mail and must take a break for awhile to catch up. We hope to be accepting new questions again soon. Thank you!

Need help with plant identification, visit the plant identification page.

rate this answer
9 ratings

Friday - July 31, 2009

From: Denison, TX
Region: Southwest
Topic: Shade Tolerant
Title: Shade trees with a tap root
Answered by: Nan Hampton


I need a list of shade trees with a tap root system. I would also like the tree to grow at a medium to fast rate. I will be planting near a concrete wall and do not want the roots to do any damage to it.


Although trees are generally divided into two groups by root type—tap root trees (such as oaks, hickory, walnut, conifers) and lateral, or fibrous, root trees (maples, ash, cottonwood)—this distinction is most evident as seedlings or saplings. Once the tree is planted and begins to mature, the distinctions between the root types become less pronounced. Then, the depth and lateralness of the roots is greatly dependent on the soil condition. Highly compacted soils, soils with low oxygen content and soils where the water table is near the surface are not likely to produce a strong tap root. Their roots are more likely to be lateral and located very near the surface with the majority of the roots located in the top 12 inches of soil. Also, it is important to realize that the spread of the roots can be at least 2 to 4 times greater than the drip line of the branches.

You can read the recommendations from Iowa State University Extension Service for Sidewalks and Trees which bases the distance trees should be planted near pavement on the mature height of the tree. Their recommendations are:

1. trees with a mature height of less than 30 feet, 3-4 feet from pavement,
2. trees with a mature height of 30 to 50 feet, 5-6 feet from pavement,
3. trees with a mature height of greater than 50 feet, at least 8 feet from pavement.

You could consider installing some sort of root barrier between the tree and the wall.  Here is more information about root barriers.

All that said, here are some trees that are recognized as having tap roots.  All of these would be considered medium-sized or small trees with a maximum height of less than 50 feet.

Fraxinus texensis (Texas ash)  has a rapid growth rate and is long-lived, 30 to 45 feet.  It  also has beautiful fall foliage.  Here is  more information.

Acer grandidentatum (bigtooth maple) has both a tap root system and lateral roots, a moderate growth rate up to 50 feet and beautiful fall foliage.  Here is more information.

Juglans microcarpa (little walnut) has a moderate growth rate of 20 to 50 feet.  Here is  more information.

Quercus buckleyi (Buckley oak) has moderate growth of 15 to 50 feet and colorful fall foliage.  Here is more information.

Cercis canadensis (eastern redbud) has a rapid growth rate of 15 to 30 feet.  Here is more information.

Fraxinus texensis

Acer grandidentatum

Juglans microcarpa

Quercus buckleyi

Cercis canadensis




More Shade Tolerant Questions

Ornamental grasses under desert willows from Dallas, TX
September 06, 2013 - I am planning on planting 3 desert willows in full sun, below the power lines at the back of my back yard in the White Rock Lake area of Dallas. I would like to plant some ornamental grasses in the be...
view the full question and answer

Evergreen Deck Plant for Oregon
May 29, 2011 - Need evergreen shrub to grow in shade in container 5ft tall for deck.
view the full question and answer

Deer-resistant, shade tolerant evergreens for privacy in Milford MI
April 12, 2010 - I'm looking for deer resistant evergreens that will be planted in the shade. I need the evergreens to hide an area I don't want to see from my home. Hence, they need to go tall. Can you give me a r...
view the full question and answer

Arborvitae thinning in Bucks County, PA
April 09, 2010 - My arborvitae trees are about 11 ft. tall. I had them put in about 3 years ago. They were 8 to 10 ft. when planted. After the first year, I have noticed they are thinning to the point where you can se...
view the full question and answer

Straggler daisy as a ground cover in Florida
April 21, 2015 - I live in Hillsborough county,FL. My yard has two large oak trees and is very shady. I am looking for a shade resistant ground cover that will do well for a yard used by children to play. I was told...
view the full question and answer

Support the Wildflower Center by Donating Online or Becoming a Member today.
© 2016 Lady Bird Johnson Wildflower Center