Excised embryos of barley were cultured on a synthetic medium and their growth rate was determined to be at least equal to that of natural embryos in vivo. Embryos, 0.4 mm when excised, averaged 3.5 mm in length after 10 days’ culture. Morphogenetically, the development of cultured embryos and proembryos (0.15–0.25 mm) duplicated normal embryogenesis. Some embryos continued to grow in culture and became up to 4.5 times larger than natural embryos, but most of the increase was due to scutellar overgrowth. Proembryos of 0.1 mm length or less did not follow normal development patterns but formed protocorm‐like embryos with several shoots and roots. It is suggested that embryonic form in barley may be determined in later stages of proembryonic growth, since earlier proembryos exhibited morphogenetic plasticity in culture.