Why are plants like white bryony harder to control than plants like prickly lettuce?

Question answered by Carson Kantack, Ecologist, INL ESER Program

Prickly Lettuce (top) and Prickly
Lettuce Taproot
Photo courtesy of NC State
University Extension Agency

The main factor really comes down to the different root systems these plants exhibit. Plants like prickly lettuce (Lactuca serriola) tend to have a taproot that is small and simple. This is a characteristic typically exhibited in a lot of common plants that take only 1-2 years to go through their life cycle. So, when you go to pull a plant like prickly lettuce, it should be relatively easy to get most of the root with it which will kill the plant.

Plants like white bryony (Bryonia alba) have a more complicated root system. White bryony has a tuberous root which typically are the size of a one-liter soda and they can be larger or smaller. The root contains the plants food reserves which is why you can’t kill the plant by simply pulling the vines. If you were to just pull or trim away the vines, the plant would just re-sprout new vines from its roots and start over. The truth is that white bryony is a very hard plant to control and it may take a few years before you can

potentially eradicate it. You have to locate the root system, which will be where the vines are coming out of the ground. After you have done this, use a shovel and try to remove as much of the root as possible. Try to get a few inches removed from the root. This will most likely need to be repeated in order to eventually get rid of white bryony.

White Bryony (top)
Photo courtesy of the Idaho
Weed Awareness Campaign
White Bryony Tuberous
Roots (bottom)
Photo courtesy of Post Register

For those that are willing to use a chemical method of control, drilling into the root a few inches and then applying high concentration glyphosate that is labeled for cut-stump treatments have proven to be effective in some cases. If you don’t own a drill, then use a shovel and cut the root a few inches down before applying the herbicide should work too.

Root System Identification
Many edible roots can be found in the produce section of the grocery store.
Yams, beets, parsnips, turnips, rutabagas, carrots, yucca, kohlrabi, onions, garlic, celery root, horseradish, jicama, radishes, and ginger are all considered roots. Because root vegetables grow underground, they absorb a great amount of nutrients from the soil. They are packed with a high concentration of antioxidants, Vitamins C, B, A, and iron.

Can you guess what system of roots the edible roots you find have? Check out the definitions below.

Tap root system: A straight tapering root growing vertically downward, and usually edible.

Tuberous root system: The short, thickened, fleshy part of an underground stem, which can grow new shoots.

Fibrous root system: Forms a dense network of roots that is closer to the soil surface. Grass, wheat and corn are examples of fibrous root system.

Root Hunt

You will need: plastic bag

  • Head outside to gather roots. Pull weeds, grass, and other plants carefully to expose their roots and place them in the bag. Make sure you have permission to pull plants around homes or parks.
  • Spread newspaper on the floor and spread out your collected roots. Try to remove as much soil as possible. Did you gather examples of fibrous roots, tuberous roots and taproots?

Answer Tubers: yams, potatoes, beets, sweet potatoes, ginger and jicama
Taproots: carrots, radishes, turnips, beets

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