Native Plants

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Monday - August 13, 2012

From: Memphis, TN
Region: Southeast
Topic: Drought Tolerant, Trees
Title: Tree to replace Betula nigra (River birch) in Memphis
Answered by: Nan Hampton

QUESTION:

HI Mr. Smarty Pants, I think I need to replace the river birch tree in my west-facing front yard in Memphis, TN. I have sun all day, but it gets really hot in the afternoon. The soil in my yard is generally dry and I think mine may be alkaline as the tree leaves are yellow-tinged and shed all year. It also loses small branches whenever there is moderate wind. Due to our summer droughts, I am afraid the roots have begun to invade the plumbing pipes that run under the front yard from the street. Can you recommend a better type tree to replace it with based on the soil type, hot temperatures and summer droughts? There are no overhead power lines to worry about and I also want one that is non-toxic to pets. Thanks, Anne

ANSWER:

Betula nigra (River birch) doesn't sound like the best tree for your dry, sunny yard. From the information on the species page, I suspect it is the dry conditions that have caused the leaves to turn yellow and fall off. You should contact your University of Tennessee Extension – Shelby County to learn how to get your soil pH tested to help you determine what tree will grow best there. You can choose a tree yourself by going to our Tennessee Recommended page and using the NARROW YOUR SEARCH option to choose "Tree" from General Appearance, "Sun" from Light Requirement and "Dry - no signs of moisture" from Soil Moisture. From this list, here are suggestions that are all native to Shelby County:

Quercus muehlenbergii (Chinkapin oak) requires alkaline soil (pH greater than 7.2)

Quercus rubra (Northern red oak) requires acidic soil (pH less than 6.8)

Quercus alba (White oak) will grow in acidic soil (pH less than 6.8) and in circumneutral soil (pH 6.9 to 7.2)

Carya glabra (Pignut hickory) grows in circumneutral soil (pH 6.9 to 7.2)

The acorns of the oaks can cause gastro-intestinal distress if eaten. Poisonous Plants of North Carolina site says: "CAUSES ONLY LOW TOXICITY IF EATEN." The University of Pennsylvania Poisonous Plants says that Quercus species can cause oak poisoning in cattle, sheep and horses. Quercus species are listed as toxic for cattle on the Canadian Poisoous Plants Information System and Cornell University: Plants Poisonous to Livestock. None of the oak species are listed on the ASPCA list for dogs. Carya glabra is not listed as toxic on any of the toxic plants databases listed below. It is, in fact, listed as "non-toxic" on the ASPCA list for dogs.

Here are toxic plant databases you can search:

ASPCA: Toxic and Non-Toxic Plant List – Dogs

Poisonous Plants of North Carolina

University of Pennsylvania Poisonous Plants

Canadian Poisonous Plants Information System

Cornell University: Plants Poisonous to Livestock

Toxic Plants of Texas