Communication: High-quality Si or SiC nanowires sheathed with SiOx (shown in the Figure; the SiOx sheath is lighter in the transmission electron micrograph) are reported to be produced by direct heating of SiC under CO atmosphere in the presence of iron powder or ferrocene. This simple route is also shown to lead to three-dimensional SiO2 nanoflowers if fine Co power is used as the catalyst instead of iron. Quasi-one-dimensional nanostructures have potential in applied nanotechnology.