If you are talking about potted plants, it could be a harmless (and common) fungus called saprophytic fungus. It usually results from a combination of over watering, poor drainage, and old or contaminated potting soil. If any or all of those conditions ring true, repot the plant with new soil (and possibly a pot that drains better) and water less frequently.
If you are talking about potted plants, it could be a harmless (and common) fungus called saprophytic fungus. It usually results from a combination of over watering, poor drainage, and old or contaminated potting soil. If any or all of those conditions ring true, repot the plant with new soil (and possibly a pot that drains better) and water less frequently.