Fungi are an organism of the Kingdom Fungi lacking chlorophyll and feeding on organic matter, according to the Princeton University website. Fungi transplanted to potting soil due to contamination of the soil and from airborne fungal reproductive spores. Typically, fungi located in potted plants such as Leucocoprinus birnbaumii, white mold, and warm weather mushrooms are not harmful to the plant, but can be harmful if eaten or if spores are released in the air.
The common fungi Leucocoprinus birnbaumii fungi grow in potting soil. According to Thomas J. Volk, professor at the University of Wisconsin-La Crosse, the fungi can be identified by their very bright yellow color when they first appear, and then by their pale yellow color as the mushroom cap expands. The mushroom cap releases reproductive spores, which lead to further soil contamination. Leucocoprinus thrives in warm indoor climates, which allows for easy dispersal to other potted plants through the release of spores. This type of fungi is not poisonous to humans in small quantities and does it hurt plants, but they can be unsightly. Common methods of control are to change the potting soil, or to remove the mushroom cap so that reproduction is not possible.
White mold or Sclerotinia disease is caused by the fungus Sclerotinia sclerotiorum, according to the North Dakota State University and U.S. Department of Agriculture website. Sclerotinia sclerotiorum harms a variety of indoor and outdoor ornamental plants, as well as a variety of crops. The fungus causes wilt, rot and blight, which can destroy indoor potted plants quickly without any early symptoms. Symptoms include a dark green greasy appearance of plants, brown to gray lesions on stems and in humid climates, white fluffy mold growth. White mold thrives in poor drainage conditions and humid climates. Common solutions for preventing white mold are to increase water drainage and to place the plant in a nonhumid area, either indoors or outdoors.
Warm Weather Mushrooms
Warm weather mushrooms are a different variety than lawn mushrooms, as they prefer the warm indoor climate as opposed to the cooler outdoor environment. The growth of mushrooms in potted plant soil is not harmful to the plant or to people if not eaten. However, they can cause an unsightly appearance. Contaminated soils carry fungal mushroom spores, which is nearly impossible to identify upon purchase. Common methods of prevention are fungicides and the removal of mushroom caps, which stops reproduction.