Barrelier’s Speedwell (Veronica barrelieri Schott ex Roem. et Schult., Plantaginaceae)—Potential of Free Volatile Compounds for Horticulture

Barrelier’s Speedwell or Veronica barrelieri Schott ex Roem. et Schult. (syn. Pseudolysimachion barrelieri (Schott ex Roem. et Schult.) Holub (family Plantaginaceae) grows on dry grasslands and rocky slopes in southeastern Europe. Because of its attractive blue flowers arranged in dense inflorescences up to 30 cm long, this plant has great potential for horticulture, especially in dry climates. As part of studies on biologically active compounds in this species, free VCs (Volatile Compounds) were analyzed by GC-MS (Gas Chromatography with Mass Spectrometry) and micromorphological features were studied by SEM (Scanning Electron Microscopy). Free VCs from aboveground plant parts collected during flowering were characterized by a considerably high content of oxygenated diterpene phytol, followed by hexadecanoic acids, pentacosane, and caryophyllene oxide. These compounds are most abundant in the composition of VCs isolates of V. barrelieri from all five Croatian localities studied. Non-glandular and two subtypes of capitate glandular trichomes were detected on the stems, leaves and calyx of V. barrelieri. Veronica barrelieri attracts pollinators with its attractive flower appearance and specialized metabolites such as free VCs, which are environmentally friendly and possible natural botanical pesticides.