Are fungi plants?

Imagine you’re on a hike in the woods. Tall trees shade you from the Sun, and the ground beneath you is speckled with flowers and the occasional mushroom. While it’s growing out of the soil just like the flowers, a mushroom is not a plant. It’s a fungus. So, what’s the difference between plants and fungi? For centuries, fungi were included in the plant kingdom. The taxonomic kingdom Fungi was not established until the mid-1900s to distinguish them from plants—based on a few key differences. First, fungi don’t have chloroplasts. Chloroplasts are structures inside plant cells that contain chlorophyll, a green pigment responsible for converting light energy into chemical energy during photosynthesis. Plants are autotrophs and produce their own food through photosynthesis. Fungi are heterotrophs, meaning they rely on plants or animals for nutrients. They secrete digestive enzymes into the surface on which they are growing, such as a fallen log or a piece of old bread. Then the enzymes break down carbohydrates and proteins they encounter, and the fungi absorb these nutrients through their hyphae, the branching, filament-like structures that form much of the fungal body. Second, the cell walls of fungi and plants are made of different materials. Fungi were originally classified as plants because their cells have cell walls, unlike animal cells. However, most fungi cell walls contain chitin, a white substance that also makes up the outer skeletons of insects, crabs, and lobsters. Plant cells have walls that contain cellulose, a carbohydrate that, while not digestible by humans, provides nutrition for many herbivores, including cows and horses. Lastly, while plants reproduce sexually by means of seeds, fungi reproduce sexually or asexually through microscopic, unicellular spores, often dispersed by the wind or animals. When a spore lands, it germinates and forms a new fungus, similar to the way a seed might take root and grow into a new plant. Despite similarities between plants and fungi, fungi are actually more closely related to humans than they are to plants. Some food for thought on your next hike—humans share nearly half of their DNA with fungi!