InAs self-organized quantum dots (QDs) and quantum dashes (QDHs) were grown by molecular beam epitaxy on GaAs (211)B substrates. QDs with bimodal size distribution were formed at lower growth temperatures, whereas QDHs were observed at higher growth temperatures. Photoluminescence (PL) intensity and peak position of QDs and QDHs showed similar temperature dependence, whereas the excitation density dependence of the PL peak intensity and the PL peak energy of the two nanostructures was different. The blue shift in QDH peak energy with the increase of the excitation density is suggested to be due to the existence of the piezoelectric field in InAs QDHs.