Plant material and source of explants Shoot-tips (approximately 5 mm) from L. angustifolia Mill. cv. Provence Blue were surface sterilized by immersion in 70% ethanol for 20 seconds, followed by immersion in 1% sodium hypochlorite containing two drops of Tween-20® per 100 mL for 20 min under manual agitation, followed by three rinses in distilled and autoclaved water. Explants were incubated on MS medium (Murashige and Skoog 1962) containing 3% sucrose, 0.6% agar (Vetec®) and the pH was adjusted to 5.8. After five weeks, the explants presented greening shoots. The shoot multiplication was carried out on MS medium