The hairy gardenia is a straggly, woody, rainforest shrub growing up to 4 or 5 m (13 or 16 ft) tall.[7] The stems, leaves and fruits are densely covered in soft hairs, hence the common name. Stipules are present and are around 13 mm (0.51 in) long.[5] The lanceolate leaves are simple and opposite or 3-4 whorled, measuring around 18 cm (7.1 in) long by 5 cm (2.0 in) wide, dark green, and have between 11 and 14 lateral veins on either side of the midrib.[5][7][8]
Flowers are pentamerous and actinomorphic, quite fragrant and borne in small terminal groups.[7] The green calyx tube is about 30 mm (1.2 in) long with lobes reduced to small teeth.[5] The corolla is white, the corolla tube is 25–30 mm (0.98–1.18 in) long with five lobes (petals) measuring 20–30 mm (0.79–1.18 in) in length.[5] The anthers, which do not extend beyond the corolla tube, measure about 6–9 mm (0.24–0.35 in) long; the pistil about 20–25 mm (0.79–0.98 in) long.[5]
The fruits of this plant are a densely hairy drupe, somewhat pear-shaped and measuring about 20 mm (0.79 in) in diameter by 30 to 50 mm (1.2 to 2.0 in) long, including the attached calyx tube.[5][8] The body of the fruit is orange and the calyx tube is green. They contain numerous seeds about 7 mm (0.28 in) long immersed in an orange pulp.[5][8]
Flowering occurs from May to November, and fruits ripen from December to August.[8]
In a 1999 revision of the Australian species of Gardenia and Randia, published in Australian Systematic Botany, the Australian botanist C.F. Puttock reassigned this species and gave it the current combination Atractocarpus hirtus.[9]
Etymology
The genus name Atractocarpus is derived from the Ancient Greek terms átraktos, meaning "spindle", and karpós meaning "fruit", and refers to the spindle-shaped fruit of the type species. The species epithethirtus is a Latin word meaning "hairy".[8]
