The Genus Leccinum: Global Advances in Taxonomy, Ecology, Nutritional Value, and Environmental Significance

<i>Leccinum</i> is an ecologically significant and taxonomically complex genus of ectomycorrhizal fungi widely distributed across boreal, temperate, Mediterranean, and selected tropical regions. Despite its ecological, nutritional, and applied importance, no comprehensive review has previously synthesized global knowledge on this genus. This work provides the first integrative assessment of <i>Leccinum</i> research, combining a bibliometric analysis of 293 peer-reviewed publications with an in-depth qualitative synthesis of ecological, biochemical, and environmental findings. Bibliometric results show increasing scientific attention since the mid-20th century, with major contributions from Europe, Asia, and North America, and dominant research themes spanning taxonomy, ecology, chemistry, and environmental sciences. The literature review highlights substantial advances in phylogenetic understanding, species diversity, and host specificity. <i>Leccinum</i> forms ectomycorrhizal associations with over 60 woody host genera, underscoring its functional importance in forest ecosystems. Nutritionally, <i>Leccinum</i> species are rich in proteins, carbohydrates, minerals, bioactive polysaccharides, phenolic compounds, and umami-related peptides, with demonstrated antioxidant, immunomodulatory, and antitumor activities. At the same time, the genus exhibits notable bioaccumulation capacity for heavy metals (particularly Hg, Cd, and Pb) and radionuclides, making it both a valuable food source and a sensitive environmental bioindicator. Applications in biotechnology, environmental remediation, forest restoration, and functional food development are emerging but remain insufficiently explored. Identified research gaps include the need for global-scale phylogenomic frameworks, expanded geographic sampling, standardized biochemical analyses, and deeper investigation into physiological mechanisms and applied uses. This review provides the first holistic synthesis of <i>Leccinum</i>, offering an integrated perspective on its taxonomy, ecology, nutritional composition, environmental significance, and practical applications. The findings serve as a foundation for future mycological, ecological, and biotechnological research on this diverse and understudied fungal genus.