A general understanding of phloem-protein bodies is hampered by the difficulties in investigating their function and structure in vivo. Phloem-proteins have been widely regarded as a wound response mechanism. However, preparation artifacts revealed in micrographs suggest that structural relationships are susceptible to misinterpretation and that phylogenetic relationships drawn between phloem protein constituents reveal that the diverse nature of these bodies calls for further consideration across more plant taxa. This thesis work presents a high-resolution micrograph of Citrus sinensis sieve elements preserved using cryogenic fixation followed by freeze-substitution for reduced disruption of their ultrastructure. In addition, seven putative Citrus sinensis Sieve Element Occlusion-Related (SEOR) phloem proteins were bioinformatically characterized, which revealed homologs related to the SEOR1 and SEOR2 subfamilies. Based on annotations provided by the Arabidopsis thaliana SEOR protein family, the putative CsSEOR2 protein is predicted to play a more direct role in defense response while the putative CsSEOR1 protein may play a more general role in phloem wounding. Both CsSEOR1 and CsSEOR2 are predicted to play a role in phloem filament formation; however, functional studies are still needed. Finally, the phylogenetic diversity of Citrus sinensis SEORs and their malvid relatives illuminates the expansion of this family of proteins that necessitates further consideration. As referenced in the third chapter of this thesis, additional tables and figures were submitted as a single supplementary file at the time of submission.