What Is the Root Structure of Morning Glories?

The Plant

• Wild morning glories have the heart-shaped leaves and the classic trumpet-shaped morning-glory flowers of the big-flowered annual vines, but the wild vine's flowers are white or whitish pink and very small. Native to the Mediterranean and known more commonly as bindweed -- for the way its vines will tightly wrap themselves around and "bind" other plants -- wild morning glory is considered one of the world's most serious weeds. It spreads primarily from seed. Each plant can produce more than 500 seeds, and these seeds can remain viable in the soil for 20 years or more.

Root Structure

• Several features make the morning glory's root system almost indestructible. The very extensive system of cordlike, energy-storing whitish roots features a primary root or taproot that can reach depths of 10 feet. Lateral roots grow out from buds along the taproot and develop rhizomes in early spring, primarily in the top 2 feet of soil. If rhizomes reach the soil surface -- through cultivation or other soil disturbance -- they establish new crowns that can generate new plants.

Preventing Spread

• Morning glory spreads primarily from seed, so do everything possible to prevent established plants from setting seed, especially by hoeing away or otherwise removing top growth regularly. Do not compost it either; throw all vegetation in the trash. Most effective for controlling spread is shading plants -- with competing flowers or crops -- because shaded plants won't flower or produce seed. You can also "outcompete" with a healthy, thick lawn. Don't dig up or cultivate roots unless you use mechanical cultivation as an eradication approach -- a process that takes three to five years when undertaken agriculturally, one that requires total commitment. Cultivating to break up the root system just spreads morning glories -- because rhizomes or pieces of rhizomes that make it anywhere near the soil surface will start countless new plants in the presence of sunlight and water.

Eradicating It

• Killing the roots with a steady suppression campaign is the only way to eradicate wild morning glory -- and this will take a few years. Consistent and careful use of glyphosate herbicide, applying it carefully with a sponge brush to every emerging shoot, will knock each plant out in two or three years. Washington State University Extension suggests starting after cooler weather starts to set in, because plants are starting to pull nutrients back down to the roots and will pull in the herbicide too. At first you'll apply glyphosate weekly, but eventually the worst will be over and you'll only apply it monthly to surviving shoots. Spring application is also effective.