Bursaria spinosa is a small tree or shrub in the family Pittosporaceae. The species occurs mainly in the eastern and southern half of Australia and not in Western Australia and the Northern Territory. Reaching 10 m (35 ft) high, it bears fragrant white flowers at any time of year but particularly in summer. A common understorey shrub of eucalyptus woodland, it colonises disturbed areas and fallow farmland. It is an important food plant for several species of butterflies and moths, particularly those of the genus Paralucia, and native bees. Description Bursaria spinosa has a variable habit, and can grow anywhere from 1 to 12 m high. The dark grey bark is furrowed. The smooth branches are sometimes armed with thorns, and the leaves are arranged alternately along the stems or clustered around the nodes and have a pine-like fragrance when bruised. Linear to oval or wedge-shaped (ovate, obovate or cuneate), they are 2–4.3 cm long and 0.3–1.2 cm wide with a rounded apex. The fragrant flowers can occur at any time of year, but mainly appear in the summer. They are arranged in leafy pyramid-shaped panicles. Taxonomy and naming First collected by Europeans in the vicinity of Port Jackson, Bursaria spinosa was first formally described by Antonio José Cavanilles in 1797 in his book, Icones et Descriptiones Plantarum. It is known by many common names, including Australian blackthorn, blackthorn, Christmas bush, mock orange, native blackthorn, native box, native olive, prickly box, prickly pine, spiny box, spiny bursaria, sweet bursaria, thorn box and whitethorn. Summer flowering has given rise to the name (Tasmanian) Christmas bush in Tasmania and South Australia (not to be confused with Prostanthera lasianthos). Indigenous names recorded include kurwan in Coranderrk, Victoria, and geapga from Lake Hindmarsh Station. Bursaria spinosa is highly variable in appearance and habit, as are other species within the genus, and there have been several attempts at classification since their discovery. For example, in 1893, Jules Alexandre Daveau, in Désiré Georges Jean Marie Bois's Dictionnaire d'Horticulture, described varieties inermis (meaning "without spines") and macrophylla ("large leaves"), but var. macrophylla was a nomen illegitimum because it had already been used by William Jackson Hooker in 1834. A 1999 revision of the genus recognised only two subspecies and the names are accepted by the Australian Plant Census: Bursaria spinosa subsp. lasiophylla (E.M.Benn.) L.Cayzer, Crisp & I.Telford has shorter, wider leaves and smaller flowers than the autonym,