Dihydrodipicolinate synthase (DHDPS) is an oligomeric enzyme that catalyses the condensation of pyruvate and aspartate semialdehyde in the first step of the lysine biosynthesis pathway of bacteria and plants. DHDPS from bacteria adopts a ‘head-to-head’ dimer-of-dimers; whilst the enzyme from plants forms a ‘back-to-back’ structure. Despite the differences in quaternary architecture, the bacteria and plant tetramers are thought to have evolved to attenuate excessive protein dynamics of the functional dimeric unit. It is thus of interest to study the structure and function of primitive plant species, such as the moss Physcomitrella patens (Pp). Interestingly, the genome of P patens shows the presence of two dapA genes that potentially encode DHDPS enzymes. Sequence analysis reveals that the putative protein products of these genes contain all the key residues for enzymatic activity and lysine-mediated allosteric inhibition. This formed the basis of the hypothesis to be examined in this study. Pp-DHDPS1 and Pp-DHDPS2 were cloned, expressed in E. coli, purified to >95% homogeneity, and shown by mass spectrometry to have the correct primary structure. CD spectroscopy and analytical ultracentrifugation studies were then employed to demonstrate that the recombinant enzymes adopt an α/ß structure and surprisingly exist as a mixture of higher-order oligomers in solution. However, enzyme kinetic studies show that the heterogeneous multimeric forms of Pp-DHDPS1 and Pp-DHDPS2 are active and allosterically inhibited with similar kinetic properties of homotetrameric plant orthologues. The results of this study offer insight into the molecular evolution of DHDPS; but many questions arise that will be addressed in future studies, including why are there two functional DHDPS enzymes in P. patens and why do these enzymes adopt non-canonical oligomeric forms but yet retain similar activity to tetrameric orthologues?