Litmus
Used for testing whether a substance is acid or alkaline.
Alcea rosea (Rose trémière) - Alkanna tinctoria (Alcanette) - Iris versicolor (Iris versicolore) - Malva sylvestris (Grande mauve) - Primula parryi - Sambucus nigra (Sureau) - Viola odorata (Violette odorante) - Viola tricolor (Pensée tricolore)