The chapter "Gene Flow in Seed Plants" by Donald A. Levin and Harold W. Kerster explores the dynamics of gene dispersal within and between plant populations, a topic of significant interest to plant breeders and seed producers for decades. Initially, anecdotal evidence suggested extensive gene flow, but more recent studies have revealed that actual gene flow levels are often much lower than previously thought. The chapter aims to organize and synthesize information on potential and actual gene flow, focusing on pollinator foraging, pollen flow in animal-pollinated and wind-pollinated plants, seed dispersal patterns, and the implications for plant population structure. "Potential gene flow" refers to the theoretical deposition of pollen and seeds from a source over a certain distance, while "actual gene flow" refers to the actual incidence of fertilization and establishment of reproductive individuals. There can be a significant disparity between these two measures. Pollen flow is primarily driven by animals or wind, with animal pollination being more efficient and prevalent in closed communities like tropical rainforests, whereas wind pollination is common in open, arid regions such as prairies and temperate forests. The chapter provides insights into the nature and regulation of these processes, highlighting their importance in understanding plant population dynamics and evolution.The chapter "Gene Flow in Seed Plants" by Donald A. Levin and Harold W. Kerster explores the dynamics of gene dispersal within and between plant populations, a topic of significant interest to plant breeders and seed producers for decades. Initially, anecdotal evidence suggested extensive gene flow, but more recent studies have revealed that actual gene flow levels are often much lower than previously thought. The chapter aims to organize and synthesize information on potential and actual gene flow, focusing on pollinator foraging, pollen flow in animal-pollinated and wind-pollinated plants, seed dispersal patterns, and the implications for plant population structure. "Potential gene flow" refers to the theoretical deposition of pollen and seeds from a source over a certain distance, while "actual gene flow" refers to the actual incidence of fertilization and establishment of reproductive individuals. There can be a significant disparity between these two measures. Pollen flow is primarily driven by animals or wind, with animal pollination being more efficient and prevalent in closed communities like tropical rainforests, whereas wind pollination is common in open, arid regions such as prairies and temperate forests. The chapter provides insights into the nature and regulation of these processes, highlighting their importance in understanding plant population dynamics and evolution.