Fig. 1

a Examples of diterpenoids reported from E. denticulata subsp. trisulcata: 8,17-dihydroxyserrulat-14-en-19-oic acid (1) [52]; E. drummondii: 7,8-dihydroxy-16-caffeoyloxyserrulat-19-oic acid (2), 7,8-dihydroxyserrulat-14-en-19-oic acid (3) [19]; E. lucida: 5-hydroxyviscida-3,14-dien-20-oic acid (4), (3Z, 7E, 11Z)-15-hydroxycembra-3,7,11-trien-19-oic acid (5) [18]. Bright field images of Eremophila spp. leaf cross sections: b E. denticulata subsp. trisulcata, (c) E. drummondii and (d) E. lucida. Arrows indicate resin layer coating the leaf surface, filled arrowheads indicate glandular trichomes, empty arrowheads indicate raised stomata and stars indicate internal oil glands. Scale bar = 100 μm