There remains no truce between me and misteltoe

Published 10:01 am Friday, March 6, 2020

It won’t be long now and one of my landscape peeves will be out of sight and thus out of mind. When the oaks leaf out, the mistletoe will be hidden from view. In the younger green ash yard trees, I’ve done battle with mistletoe for years with no truce in sight.

There are about 1,500 species of mistletoe worldwide and all of them are parasitic to some degree. Most are labeled as hemiparasitic because they do carry out low levels of photosynthesis, making a little bit of their food. But they steal most of their food and water from host plants like trees.

We sometimes say mistletoe has roots growing into tree bark and that’s close to right. The structures mistletoe uses to anchor itself and draw in nutrients from hosts are properly called haustorium.

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As for other parasitic plants known to be in this corner of the world, the vine dodder is one I have seen a few times in the county. Like most plants, there are many species of dodder. Ours is yellow or orange and looks like a large spread out wad of string hanging over another plant. The few I saw were growing over the tops of abandoned fences covered with honeysuckle and other weeds. Dodder doesn’t have leaves or roots. It is all stem. It does flower and make seeds, which is how it spreads and gets started in new places. When a dodder seed germinates, it does send down a single rootlet to get food from the soil. That rootlet lives about a week and if the new vine doesn’t latch to a host by then, it dries up and dies. 

Indian Paint Brush is a plant known mostly for its contribution as a wildflower or meadow flower.

A few years back I drove to Texas hill country during alleged peak bluebonnet bloom and saw a lot more parasitic Paint Brushes than bluebonnets.

So why would such a pretty wildflower be deemed a parasite?

Well, because it gets most of its nutrition by invading other plant species. In the case of Paint Brushes, they have true roots that grow down in the soil until they contact other plants’ roots, which they invade for life, derive what they need and send it upward. For the most part, it is grasses that are parasitized by Paint Brushes. 

Just because one species adheres to another does not mean the first is a parasite.

Spanish moss is certainly not a parasite. It uses trees strictly for physical support. It does no harm to its hosts. The moss gets its needed water and minerals from the air.

And there are lichens that grow on trees and other plants, but do no harm. A lichen is made up of two unrelated things growing together as one structure, those two being a fungus and an algae. Lichen buildup is sometimes more profuse on dying and dead wood, but that “fuzzy stuff” did not kill the plum tree. Lichens just love dead plum and Crepe Myrtle limbs.

 

Terry Rector writes for the Warren County Soil and Water Conservation District.