Due to exceptional chemical stability and excellent mechanical, thermal, and electro-optical properties, the InGaN ternary alloy is a material of a choice for light emitting diodes (LEDs) and lasers operating in UV or near-UV spectral range. The usefulness of the material also stems from bandgap tunability; energy bandgap can be adjusted over broad range by proper choice of In concentration. For strained InGaN thin films grown on GaN, as the In concentration increases above ~10%, formation of structural defects and compositional disorder have been observed by high resolution TEM and atomic force microscopies, and by X-ray diffraction. On the other hand, for GaN semiconductor, it has been already demonstrated that shift from planar two-dimensional (2D) geometry of films to one-dimensional (1D) wires substantially suppresses the density of defects. So far, our attempts in growing ternary InGaN wires by MBE with ~20% In composition (suggested emission peak ~530 nm) uniformly distributed along the growth axis yield unexpected results. While the SEM micro-photographs unambiguously demonstrate successful non-catalytical growth of wires, low temperature photoluminescence (PL) studies, performed on wire ensembles, revealed broad emission spectra covering 360-700 nm range. In contrast, photoluminescence of a ~200 nm thick InGaN thin film with ~20% In content is well centered around 530 nm. At room temperature, a broad emission of wires collapses into 500-550 nm spectral range. To pinpoint the origin of a broad photoluminescence of wire ensembles, single wire PL and energy dispersive X-ray (EDX) measurements have been carried out. In PL experiments, substantial variations of the InGaN emission spectra of individual wires have been observed. While some wires show exhibit strong single peak emission, weaker and multiple peak emission of another wires indicates the essential intra-wire fluctuations of the In composition. On a separate set of single wires, EDX revealed gradual changes of In composition along the growth axis with the maximum concentration peaked near the wire tip. The EDX data in conjunction with scanning transmission electron microscopy and atomic force microscopy allowed us to estimate low temperature emission quantum yield of single wires. The estimates resulted in QY >10% and indicated that the surface of InGaN wires does not terribly quench the emission. The room temperature QY is about 10 times less than that measured at 4K. Currently, the development of a growth model for graded InGaN wires is in the progress, but, nevertheless, our data distinctly demonstrate the successful synthesis of compositionally graded InGaN wires using plasma assisted MBE. These defect-free wires offer not only a potential solution for a material suitable for the green emission but have potential applicability to broadband emission devices possibly as integrated phosphors.