A meta-analysis of local adaptation in plants reveals that local plants generally perform better than foreign plants at their site of origin, with this being true in 71.0% of studied sites. However, local plants perform better at both sites of a pairwise comparison in only 45.3% of cases, indicating divergent selection and thus evidence for local adaptation. Local adaptation is more common in large plant populations (>1000 flowering individuals) than in small ones (<1000 flowering individuals), where it is rare. The degree of local adaptation is independent of plant life history, spatial or temporal habitat heterogeneity, and geographic scale. The study suggests that local adaptation is less common in plant populations than generally assumed, and that population size plays a fundamental role in evolutionary theory. Small populations are less likely to adapt to changing environments due to reduced genetic diversity and increased inbreeding. The results highlight the importance of population size for evolutionary theory and the ability of small populations to cope with environmental changes. The study also shows that local adaptation is independent of species, habitat, and study characteristics, and that geographic distance does not significantly affect the strength of local adaptation. The findings reinforce the importance of population size for evolutionary theory and the need for further research on the factors influencing local adaptation.A meta-analysis of local adaptation in plants reveals that local plants generally perform better than foreign plants at their site of origin, with this being true in 71.0% of studied sites. However, local plants perform better at both sites of a pairwise comparison in only 45.3% of cases, indicating divergent selection and thus evidence for local adaptation. Local adaptation is more common in large plant populations (>1000 flowering individuals) than in small ones (<1000 flowering individuals), where it is rare. The degree of local adaptation is independent of plant life history, spatial or temporal habitat heterogeneity, and geographic scale. The study suggests that local adaptation is less common in plant populations than generally assumed, and that population size plays a fundamental role in evolutionary theory. Small populations are less likely to adapt to changing environments due to reduced genetic diversity and increased inbreeding. The results highlight the importance of population size for evolutionary theory and the ability of small populations to cope with environmental changes. The study also shows that local adaptation is independent of species, habitat, and study characteristics, and that geographic distance does not significantly affect the strength of local adaptation. The findings reinforce the importance of population size for evolutionary theory and the need for further research on the factors influencing local adaptation.