In(x)Ga(1-x)As wurtzite nanoneedles are grown without catalysts on silicon substrates with x ranging from zero to 0.15 using low-temperature metalorganic chemical vapor deposition. The nanoneedles assume a 6 degrees - 9 degrees tapered shape, have sharp 2-5 nm tips, are 4 microm in length and 600 nm wide at the base. The micro-photoluminescence peaks exhibit redshifts corresponding to their increased indium incorporation. Core-shell InGaAs/GaAs layered quantum well structures are grown which exhibit quantum confinement of carriers, and emission below the silicon bandgap.