Iridoids are non-canonical monoterpenoids produced by both insects and plants. The iridoid dolichodial is produced by Teucrium marum (cat thyme) and multiple insect species, but its biosynthetic origin remains unknown. We set out to determine the genomic, enzymatic and evolutionary basis of iridoid biosynthesis in T. marum. We generated a de novo chromosome-scale genome assembly for T. marum using Oxford Nanopore Technologies long reads and proximity-by-ligation Hi-C reads. The 610.3 Mb assembly spans 15 pseudomolecules with a 32.9 Mb N50 scaffold size.