Are the leaves of the ligustrum poisonous?
The answers in internet are not very precisely: “The leaves and berries of Ligustrum species are poisonous and possibly fatal particularly L. vulgare, the toxicity of this species has not been confirmed (Everist 1974; Shepherd 2004). The species pollen may cause some allergies (Cariñanos et al 2002).” http://www.dpi.vic.gov.au/dpi/vro/vrosit… But it is sure that liguster leaves have a bitter taste and your chocolate leaves might have too. Therefore it could be better to chose atoxic neutral or even spicy leaves like bay leaves e.g. for pattern. They have distinct decorative veins and will give the chocolate a delicate and surprising taste. One day later: Length of liguster leaves is about 5 cm, length of bay leaves 2.5 to 7.5 cm and they are 1.6 to 2.5 cm in breadth. You should find large ones in a good shop for spices.
