The leaves are opposite, simple ovate to lanceolate, with an entire or crenate margin; they are often aromatic.

The accidental cross that produced it occurred in the garden of Arthur Simmonds at Clandon, near Guildford, Surrey.

The final selection, however, was made of a self-sown volunteer that appeared under C. mastacanthus, and eventually smothered it.

[7][8] This small, deciduous, aromatic shrub has grey-green leaves and produces masses of blue flowers in late summer.

Like Buddleja, the woody stems can die back in the winter, particularly in colder climates and on heavy soils.