The George Washington Memorial Parkway is home to lush forests, teeming wetlands, and verdant meadows. However, none of these spectacular ecosystems would function without the vital roles filled by the fungal community. This enigmatic group of organisms not only possess an incredible level of diversity in both form and function, but also plays a key role in maintaining the health and diversity of plant and animal communities.
Although they may superficially resemble plants, fungi occupy a separate taxonomic kingdom, "fungi." During their long, but ongoing, evolution; the ancestors of fungi diverged from the ancestors of plants sometime around one billion years before present, and from animals only slightly more recently. In addition to true fungi, there are also fungus like organisms that (through convergent evolution) have evolved a lifestyle similar to that of fungi; such as slime moulds, and a group of organisms represented by the microorganism that causes potato blight disease in potato crops.
A billion years of evolution has produced many unique features that characterize fungi. Two of their most important features pertain to the way in which fungi grow, and the composition of their chromosomes. Firstly, fungi exhibit two distinct forms of growth. They can grow as hyphae, which are a series of branching root-like filaments that expand by dividing behind the leading tip of individual hypha. The mass formed by these branching hyphae is termed the mycelium. Fungi can also grow as free living yeasts, which grow by fission of individual cells. A few fungi, called "Dikaryotic Fungi" are even capable of switching between these two types of growth. Secondly, the cells of fungi contain haploid nuclei. Unlike the cells of plants and animals (excluding special reproductive cells), fungal cells only contain half the organism's chromosomes at any given time. Despite these unique characteristics; fungi, much like animals, are incapable of producing their own food, and must obtain their food by absorbing it from their environment. Whether it's from the soil, or from the dead or living tissues of plants, animals, or even other fungi, the search for energy continues to drive the evolution of fungi within our ecosystems.