Secretory Structures and Essential Oil Composition in Santolina chamaecyparissus L. Cultivated in Northern Italy

Santolina chamaecyparissus L. (Asteraceae), cultivated at the Ghirardi Botanic Garden (Toscolano Maderno, Brescia, Northern Italy) of the University of Milan, was investigated adopting a multidisciplinary research approach: micromorphological and histochemical, with special attention on the secretory structures producing secondary metabolites; phytochemical, with the analysis of the essential oil (EO) composition from the air-dried, flowered aerial parts gathered once per year across two consecutive years (2021 and 2022); bio-ecological, focusing, based on literature data, on the biological activity and ecology of the main EO compounds; didactic–educational, with the ex novo realization of an interpretative apparatus at the study site. Two distinct types of secretory structures were described: biseriate glandular trichomes and secretory ducts, both producing an oleoresin rich in flavonoids. Phytochemical analysis revealed stable EO profiles across the two years with regards to the total number of compounds (39 vs. 40), the main chemical classes (oxygenated monoterpenes (72.67% vs. 78.61%) and monoterpenes hydrocarbons (15.06% vs. 10.48%) and the key single components (artemisia ketone, 52.74% vs. 55.67%; camphor, 13.00% vs. 16.18%). The literature data on the bio-ecology of the main compounds allowed us to confirm antimicrobial, antioxidant, and anti-inflammatory properties. Concerning the dissemination actions, the outcomes of this multidisciplinary work were integrated into a new interpretive apparatus for S. chamaecyparissus at the Ghirardi Botanic Garden. The research results enhance our understanding of this species, supporting its potential EO application in medicine and agriculture.