Monoterpene synthase (TPS) involved in the biosynthesis of monoterpene natural products of the 'cineole cassette', volatile compounds present in floral scent (PubMed:21527560). Catalyzes the conversion of (2E)-geranyl diphosphate (GPP) into alpha-terpineol and, as minor products, sabinene, beta-myrcene, limonene and 1,8-cineole (PubMed:21527560). (2E)-geranyl diphosphate + H2O = (S)-alpha-terpineol + diphosphate (2E)-geranyl diphosphate = diphosphate + sabinene (2E)-geranyl diphosphate = beta-myrcene + diphosphate (2E)-geranyl diphosphate = diphosphate + limonene (2E)-geranyl diphosphate + H2O = 1,8-cineole + diphosphate Binds 3 Mg(2+) or Mn(2+) ions per subunit. Secondary metabolite biosynthesis; terpenoid biosynthesis. Monomer. Confined to flowers. In flowers, present in pistils and in the adaxial and abaxial epidermis of the petals (PubMed:21527560). Maximal enzyme activities are reached at the second day after anthesis when flowers are fully opened (PubMed:21527560). Enzyme activity levels follow a circadian oscillation, reaching a maxima at the transition from day to night (diurnal rhythm). The Asp-Asp-Xaa-Xaa-Asp/Glu (DDXXD/E) motif is important for the catalytic activity, presumably through binding to Mg(2+). Belongs to the terpene synthase family. Tpsb subfamily.