Seed Planning Unit (SPU) geometry is comprised of Seed Planning Zone geometry delineated by elevation ranges. Each SEED_PLAN_UNIT_ID relates to a SEED_PLAN_ZONE for a specific tree species and minimum/maximum elevation in meters. Seed Planning Units only apply to Genetic Class A (orchard/parent tree). Some coastal species also have a latitude range. The geometry can be joined to the SEED_PLAN_UNIT table using SEEED_PLAN_UNIT_ID to determine the Seed Planning Zone, tree species and elevation range.