thallus
/ˈθæləs/
noun
- A simple plant body that is not divided into roots, stems, and leaves, found in algae, fungi, and lichens.
- Under the microscope, the thallus of the seaweed looked like a flat, green ribbon.
- The lichen's thallus clung tightly to the surface of the old stone wall.
- Mushrooms are the fruiting bodies of a fungus whose thallus lives underground.