Localized surface plasmons within silver nanocubes less than 50 nm in size were investigated using high-resolution cathodoluminescence hyperspectral imaging. Multivariate statistical analysis of the multidimensional luminescence data set allows both the identification of distinct spectral features in the emission and the mapping of their spatial distribution. These results show a 490-nm peak emitted from the cube faces, with shorter-wavelength luminescence coming from the vertices and edges; this provides direct experimental confirmation of theoretical predictions.