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Slime Molds, Bark Lice, and Other Landscape Oddities

Each year I receive a number of questions about odd or “alien” things in the landscape. Most of these organisms are harmless, and all of them are fascinating. Below I’ll highlight just a few of these oddities.

Slime molds are amazing organisms that belong to a ‘primitive’ class of fungi called Myxomycetes – a small group of organisms with only 700 species known worldwide. Slime molds obtain their nutrients from dead or decaying matter and are most prevalent following extended periods of wetness. Slime molds can be found in lawns, flower beds, gardens – anywhere organic matter is present. In Georgia, slime molds vary in color from blue-gray to yellow, orange or black. Slime molds ‘creep’ along slowly but may travel up to several feet a day. Slime molds do not cause any direct injury to plants. As weather conditions dry, the slime mold forms spore-producing structures and spores are blown by the wind to new locations to start the cycle over. These spore masses can appear as gray to black dusts on grasses or other plant materials. My favorite slime molds are the oddest and most descriptive like dog vomit slime mold and wolf’s milk slime mold. All of the slime molds that you may encounter in the landscape are harmless and simply cosmetic. You can wash them away with a garden hose, but they usually disappear on their own with a week or two and are fascinating to watch.

Barklice are tiny soft-bodied insects that feed on lichens and decaying matter. What most people notice in the landscape isn’t the barklice, but the webs they weave. Barklice make extensive webs that cover the branches and trunks of trees. Personally, I think it looks like the tree is wearing white pantyhose. Neither the barklice nor the webs cause any harm to the tree. You are most likely to see these interesting critters between March and October.

Bird’s nest fungus has to be one of the cutest landscape oddities. This fungus feeds on decomposing wood and the fruiting bodies look like miniature bird nests with eggs in them. The fungi are not harmful, and play an important role in recycling nutrients through decomposition. You may see these fungi in large clusters of ten to one hundred fruiting bodies. The “eggs” contain spores which are spread by splashing and rainfall.

Galls often catch the attention of homeowners this time of year. Galls are abnormal vegetative growths, most often seen on trees and shrubs. Galls are caused by the plant isolating or quarantining an intruder similar to how an oyster makes a pearl. The intruder in question is often an insect that is feeding or laying eggs, but in some plant species may be a fungal pathogen. Galls don’t usually cause significant harm and can be pruned out in most cases if you find that more desirable. Keep in mind that many gall causing insects are species of wasps, and many wasp species serve as pollinators and/or predators of garden pests.

Nostoc is a jelly-like substance that is found in overly wet turf. Nostoc is a cyanobacteria that may appear suddenly in in warm temperatures following a period of rain. Nostoc is an indication of overwatering and/or soil compaction. It will dry out and become dormant, but will revive with moisture. While not dangerous to touch, be careful walking over it – it’s very slippery!

Stinkhorns are friendly decomposing fungi. They come in a variety of colors and forms, including tentacles, webbed/baskets, and horns. They use their aroma to attract flies which spread their spores to new areas. Stinkhorns aren’t harmful but they can be a little offensive to the senses if you get too close!

Puffballs are another decomposing fungus that you may encounter in the landscape. Some look like potatoes, while others resemble tiny eggs. These include the common puffball, earthball puffball, and wolf fart puffball. (No, I didn’t make that up.) Puffballs rely on the wind to spread their spores which are emitted like a puff of smoke when triggered by outside forces such as falling rain, or being brushed or stepped on by a passing animal. You can gently squeeze them to see the puff of spores stream out of the top.

There are so many fascinating occurrences and organisms in the landscape throughout the year – and each fills a niche or serves a purpose. I encourage you to take an interest in, instead of an abhorrence to, these “oddities.” As Aldo Leopold once said, “The last word in ignorance is the man who says of an animal or plant: ‘What good is it?”