Flowerlike silicon particles are obtained by chemical etching of polycrystalline silicon polyhedrons using a mixture of hydrofluoric acid and nitric acid. The etched flowerlike particles show stable bright red photoluminescence under UV irradiation. The formation of pores with diameters of 3, 5.5, and 20 nm is revealed during etching. The etched particles exhibit superhydrophobic behavior with a contact angle of 158 degrees because of the sharp tips of their "petals". The source silicon polyhedrons are shown to possess radial grain boundaries. Preferential etching along the radial grain boundaries of the polyhedrons is thought to be the key reason for the formation of flowerlike porous silicon particles.