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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.

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Saturday - March 16, 2013

From: San Antono, TX
Region: Southwest
Topic: Septic Systems, Shrubs
Title: Tree for on top of sewer lines from San Antonio
Answered by: Barbara Medford


I am looking for an evergreen small tree with taproot to plant in a very small front yard near the sidewalk and possibly on top of or nearly on top of sewer lines. Would a Mt. Laurel be the choice? If not, what would you recommend?


We will recommend only trees native not only to North America but to the area of Bexar County TX. This is the commitment of the Lady Bird Johnson Wildflower Center, home of Mr. Smarty Plants, to encourage plants native to an area because those plants will consume less water and other resources, as well as be adapted to the climate and soils there.

Most questions that we get have been asked, in one form or another, before. Here are three previous Mr. Smarty Plant answers to give you a feel for the difficulties you are going to encounter.

Mountain Laurel over sewer lines from Tucson AZ

Tree over lateral lines from Bulverde TX

Trees over leach field from Arkansas

You will notice that in the first one, we point out that Sophora secundiflora (Texas mountain laurel)  has a taproot and is therefore very difficult to transplant. We are often asked for taproot trees that will be near pools or sewer lines; but our customers do not realize that taproot trees still have many feeder roots that go out for some distance and these are the roots that love to go shopping in sewer lines. Another difficulty is your request for an evergreen tree, which the Mountain Laurel is, of course, but there are not many others. Mountain Laurel is considered a shrub or small tree and there are a few other shrubs native to Bexar County that are evergreen and can grow tall enough to be considered trees.  They are still woody plants, of course, but at least maybe not with quite such ferocious roots as trees might have. You will note that some of these are not exactly shade trees, but they are evergreen and provide blooms. Follow each plant link to our webpage on that plant to learn if it needs shade or sun, when it blooms and what its water requiremets are.

Evergreen shrubs for Bexar County:

Chrysactinia mexicana (Damianita)

Garrya ovata ssp. lindheimeri (Lindheimer's silktassel)

Ilex vomitoria (Yaupon)

Leucophyllum frutescens (Cenizo)

Rhus virens (Evergreen sumac)

Sophora secundiflora (Texas mountain laurel)


From the Image Gallery

Chrysactinia mexicana

Lindheimer's silktassel
Garrya ovata ssp. lindheimeri

Ilex vomitoria

Leucophyllum frutescens

Evergreen sumac
Rhus virens

Texas mountain laurel
Sophora secundiflora

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