How mushrooms get their food without sunlight
A green plant is a food factory: it uses sunlight to turn air and water into organic matter, which is why plants are called producers. Mushrooms do not do this. As one review notes, mushrooms do not produce organic matter the way common green plants do [1]. Instead, they live on organic matter that already exists.
The way they get it is by breaking it down. Mushrooms possess enzyme complexes that let them attack plant cell walls, which is why they can grow on a wide variety of lignocellulosic materials — essentially dead plant material like straw, wood, and crop residues [2]. In plain terms, a mushroom is a decomposer: it digests its surroundings outside its body and then absorbs the nutrients. That is a fundamentally different way of life from a plant's.
Why the difference matters beyond biology
This feeding strategy is not just a curiosity; it is what makes mushrooms useful to people. Because they can grow on plant waste, edible mushrooms can be cultivated on materials that would otherwise be discarded, turning low-value residues into food [2]. That ability comes directly from the enzymes that let them break down plant cell walls.
The same review that contrasts mushrooms with green plants frames their global impact on human welfare as a 'nongreen revolution' [1]. The phrase captures the point: mushrooms contribute to food and medicine through a completely different route than green plants, one based on recycling organic matter rather than creating it.
What the evidence does and doesn't settle
The supplied sources agree that mushrooms differ from plants in how they produce organic matter and in their ability to break down plant cell walls [1][2]. However, these are brief summaries rather than full comparative studies, so they do not detail every difference — for example, cell wall composition or genetics — that a biologist would include. The core answer, though, is clear: mushrooms are fungi, not plants, and they make their living by decomposition rather than photosynthesis.
Sources used in this answer
Global impact of edible and medicinal mushrooms on human welfare in the 21st century: nongreen revolution
Mushrooms differ from common green plants in that they do not produce organic matter, and their global impact on human welfare has been described as a 'nongreen revolution.'
Edible mushrooms: attributes and applications
Mushrooms possess enzyme complexes that let them attack plant cell walls, enabling them to grow on a wide variety of lignocellulosic materials.