I recently had a neighbor ask me to come over and try to identify some sort of strange, alien thing that was growing out of her lawn. She had been finding these weird entities for about a week, and had been picking them out and disposing of them when she remembered I knew a lot about pests and plants. As I approached the oddity, a strange growth about 6 inches long with a white tubular base and a brownish top, I got a whiff of a nasty smell that triggered a name in my mind. What my neighbor was finding was a mushroom called a "Stinkhorn", which I had read about but had never actually seen myself in the field. As so many mushrooms do, these things grow at a remarkable speed when they shove this "fruiting body" up to produce the spores, akin to the seeds of higher plants. What was not there two days before now was nearly six inches long.
There are many kinds of stinkhorn mushrooms in the world, most from tropical countries, and it is felt that this particular species - the Lizard's Claw Stinkhorn, Lysurus cruciatus, most likely is an import from a tropical part of the world. With only a little imagination we recognize that the distinctive shape of many of the species is similar to a particular part of male anatomy, and in fact one species is given the scientific name of Phallus impudicus. All species deserve their common name of "Stink" horn, because they spread their spores in a most unappealing way - they draw blow flies to do the work for them. The spores are contained in a slimy brown ooze on the very top of the mushroom, and it is this substance which gives off the awful odor that reminds us of a mixture of fresh dog manure and a dead corpse - just the stuff that blow flies and flesh flies go for, and go for it they do. As the flies walk around on this slimy spore-mass they pick it up on their feet and transfer it to their next stop, potentially spreading the invasion of the mushroom to new places.
The visible mushrooms we see, including the Stinkhorns, are a very temporary part of a fungus growth. The actual fungus is growing happy and healthy below ground, feeding as thread-like mycelia on some kind of decaying organic material. However, when the fungus matures it can afford to spend some energy producing more of its kind, and the mushroom then rapidly shoots up above ground to produce and release the spores. For most of our typical mushrooms the spores are released as dry powder that is carried with the wind. However, nature being incredibly diverse and interesting as it is, some species have developed their own unique mechanisms, and the stinkhorn does what stinkhorns do. They employ the flies.
How Do They Grow?
The spore of a fungus serves the same function as the seeds of other kinds of plants, and if the microscopic little spore manages to land on a surface that offers it the food and moisture it needs, it can begin to grow. The stinkhorns may be spread into new environments in planting materials, landscape materials such as bark, or in some other transport mechanism involving bringing in garden materials. Of course, within a small area it also is then spread yard to yard by the flies. Perhaps, as in this case, some neighborhood dog may have left its calling on the lawn first, attracting flies to the lawn and enabling them to deposit the spores to this new place. Subsequent watering of the lawn then washed the spores down to the soil, where they found adequate decaying organic material to feed on, such as thatch buildup or buried wood in the form of old tree roots.
The process of producing the mushroom, in the case of stinkhorns, begins with a large "egg" shaped blob on the soil, which can grow to the size of a golf ball. Then, the surface of the egg ruptures and the elongating stinkhorn emerges from it, rapidly growing above the level of the turf. This part of the fungus is referred to as the "fruiting body" or sporophore, and the spores are produced to spread the species to new places. It is said that these mushrooms are edible in that egg stage, and appear to be considered a delicacy in some Chinese cultures. However, a few people have related their experiences in attempting to eat a stinkhorn, and the results to them were most unpleasant. Not only did they receive a foul taste, but the texture of the mushroom also was disagreeable, and a lingering sliminess remained in their mouths for several hours. So, they are not poisonous, but they are not attractive either, and to most of us getting past the awful odor would be difficult.
How Do We Control The Problem?
It is very likely that you cannot control these mushrooms, other than removing them as you see them and disposing of the mushroom itself. Since the great part of the fungus is growing beneath the turf and the surface of the soil, on buried wood materials, getting a chemical fungicide down to that area would be difficult. If the mushrooms seem to be clustered around a specific point you might consider that some large object is their food resource, and digging down and removing this could be helpful. However, more often the mushrooms just seem to pop up here and there throughout a lawn or garden, and a general invasion is likely to be the case.
Typical mushrooms that are found growing in a lawn really pose the same problem, and spraying chemicals onto mushrooms in the belief that this will kill the fungus invasion is not realistic. The mushroom is not the fungus infection, it is just one small part of the fungus doing one specific function. Good garden sanitation, properly preparing the soil for a lawn, regular removal of thatch buildup, and proper watering practices will all help to prevent fungus problems. Fungi rely on moist conditions and rotting plant materials for their survival, and if the soil is dry they cannot thrive. Lawns that are excessively watered may be more prone to fungus problems and the resulting mushrooms than are lawns that are watered correctly.
So, as embarrassing and socially unacceptable as it may be to be the person in your neighborhood with "stinkhorns" growing in your lawn, once they are there you may have few options to get rid of them permanently. And, if you end up having a lot of the mushrooms themselves poking up out of the lawn you may receive odd looks from passersby who wonder why your front lawn smells so very, very bad. On the bright side, you are also the one with these unusual, exotic plants growing in your yard that have such an intriguing life style to them, so be proud.