Callistemon citrinus had become established in cultivation in England by 1794 when flowering plants that were more than five years old had been observed at both Kew Gardens and Syon House and younger plants had become available in nurseries.
Callistemon citrinus - locally termed Bottle Brush - native to Australia
Leptospermone is a chemical compound (a β-triketone) produced by some members of the myrtle family (Myrtaceae), such as Callistemon citrinus (Lemon Bottlebrush), a shrub native to Australia, and Leptospermum scoparium (Manuka), a New Zealand tree from which it gets its name.