Silicon (Si) is the second most abundant element in soils and a major component of plant life. It is readily absorbed by plants, often reaching concentrations of 1% to 10% of dry matter. Despite its abundance, Si is not considered an essential nutrient for most terrestrial plants, except for members of the Equisetaceae family. However, evidence suggests that Si plays a significant role in plant growth, mineral nutrition, mechanical strength, and resistance to diseases and environmental stresses. In solution cultures, plants are often deprived of Si, leading to experimental artifacts that may distort results in studies of plant nutrition and stress responses. Si is commonly present in nutrient solutions as a contaminant, and its absence can lead to deficiencies in plants. Studies show that Si can mitigate nutrient imbalances, enhance growth, and improve resistance to fungal diseases, herbivory, and abiotic stresses like salinity and heavy metals. Si is deposited in plant tissues, primarily in cell walls, and contributes to the structural integrity of plants. It also plays a role in light interception and photosynthesis. In soil-grown plants, Si applications have been shown to improve crop yields, reduce disease incidence, and enhance resistance to pests and environmental stresses. The inclusion of Si in nutrient solutions is recommended to better reflect natural conditions and to avoid experimental biases. Silicon's role in plant biology extends beyond nutrition, influencing plant anatomy, taxonomy, and even archaeological and medical applications. Overall, Si is a critical component of plant biology, with significant implications for plant health and productivity.Silicon (Si) is the second most abundant element in soils and a major component of plant life. It is readily absorbed by plants, often reaching concentrations of 1% to 10% of dry matter. Despite its abundance, Si is not considered an essential nutrient for most terrestrial plants, except for members of the Equisetaceae family. However, evidence suggests that Si plays a significant role in plant growth, mineral nutrition, mechanical strength, and resistance to diseases and environmental stresses. In solution cultures, plants are often deprived of Si, leading to experimental artifacts that may distort results in studies of plant nutrition and stress responses. Si is commonly present in nutrient solutions as a contaminant, and its absence can lead to deficiencies in plants. Studies show that Si can mitigate nutrient imbalances, enhance growth, and improve resistance to fungal diseases, herbivory, and abiotic stresses like salinity and heavy metals. Si is deposited in plant tissues, primarily in cell walls, and contributes to the structural integrity of plants. It also plays a role in light interception and photosynthesis. In soil-grown plants, Si applications have been shown to improve crop yields, reduce disease incidence, and enhance resistance to pests and environmental stresses. The inclusion of Si in nutrient solutions is recommended to better reflect natural conditions and to avoid experimental biases. Silicon's role in plant biology extends beyond nutrition, influencing plant anatomy, taxonomy, and even archaeological and medical applications. Overall, Si is a critical component of plant biology, with significant implications for plant health and productivity.