A tornado that forms from a cumuliform cloud without a mesocyclone is called a landspout.
Landspouts are non-supercell tornadoes. Instead of developing from the organized, rotating updraft of a supercell, they usually form along a surface boundary where winds are already turning or converging. A growing cumulus or cumulonimbus cloud then stretches that low-level rotation vertically, concentrating it into a narrow vortex.
They often appear as slender, rope-like funnels beneath towering cumulus clouds and are especially common in parts of the Great Plains, including eastern Colorado, Wyoming, and New Mexico. Although many landspouts are weak, some can produce significant damage, including EF2 or EF3-level effects.
The main confusion is with a dust devil. A dust devil is a surface-based vortex that is not connected to a cumuliform cloud, whereas a landspout is a genuine tornado connected to a developing cloud. A waterspout is the comparable phenomenon over water; some waterspouts are also non-supercellular, while others form from supercells.