This collection of studies focused on characterization of maize and teosinte starches, creation of a model system for studying starch crystallinity, and examination of cyanobacterial glycogen accumulation in various media conditions. Chalco teosinte, BSSS maize, BSSS maize-Chalco teosinte cross, and commercial normal maize starches all exhibited A-type X-ray diffraction patterns, similar degrees of crystallinity, amylopectin molecular weights, and amylose contents. Chalco teosinte starch granules were small, broken, or hollow; other starch granules were spherical or polygonal. Average branch chain length was smallest for Chalco teosinte starch (degree of polymerization (dp) 23.5) and largest for commercial normal maize starch (dp 25.3). Differential scanning calortimetry analysis showed that Chalco teosinte starch had the lowest onset gelatinization temperature (610C) and enthalpy change of gelatinization (11.4 J/g), but the highest rate of retrogradation (56.2% in 7 days). Pasting properties determined using a Rapid Visco Analyzer differed widely. Chalco teosinte starch had the lowest peak viscosity (135.8 RVU), and BSSS maize-Chalco teosinte cross starch had the highest (187.3 RVU). Starch is cold-water insoluble and semi-crystalline, but glycogen is considered cold-water soluble and non-crystalline. Starch crystallinity was studied with a starch model system prepared from amorphous waxy-maize starch and highly crystalline normal-maize starch Naegeli dextrin (83% crystalline). These components, and mixtures thereof, were analyzed by X-ray diffraction and differential scanning calorimetry (DSC). Degree of crystallinity, determined by X-ray diffraction, increased linearly with increasing amounts of Naegeli dextrin. However, enthalpy change of melting and melting temperature, determined by DSC, demonstrated a second order relationship. Glycogen production by cyanobacteria (Synechocystis PCC 6803) was studied using media conditions that varied in glucose and nitrogen contents, and glycogen was extracted with ethanol only or ethanol and trichloroacetic acid. Glycogen accumulation was the highest in glucose-abundant nitrogen-deficient media (30 mg/L), but growth rate was the highest in glucose and nitrogen-abundant media. Average branch chain length ranged from dp 9.5 (glucose and nitrogen-abundant media) to dp 11.2 (glucose-abundant nitrogen-deficient media). Thus, media nutrient content influenced cyanobacterial growth rate, amount accumulated, and molecular structure of glycogen. Minor differences were observed between glycogen samples extracted with ethanol only and with ethanol and trichloroacetic acid.