Trees, shrubs or mallees, usually glabrous in adult stage. Lvs opposite for at least the first few pairs on juvenile plants, otherwise alternate, with aromatic oil glands. Fls in single or paired, axillary, usually pedunculate umbelliform cymes, or paniculate and terminal, or occasionally solitary. Bracteoles quickly caducous. Hypanthium wholly or partly enclosing ovary; sepals free or fused to form an operculum. Petals 5, always fused to form an operculum shed at anthesis. Stamens numerous, > petals, in 2 or more whorls, free or clustered into 4 groups; anthers versatile, dorsifixed or sub-basifixed and opening by discrete or confluent slits, or ± basifixed and opening by terminal pores; connective often prominent. Ovary 2-several-celled, surrounded by nectary disc; ovules numerous; style minute and inconspicuous or prominent. Fr. ± woody, composed of capsule and hypanthium, usually with loculicidal dehiscence, and teeth of valves included or exserted from hypanthium rim; viable seeds 2- c. 40.