A small to medium-sized evergreen tree, that grows up to 15 m (49 ft) tall, with up to 3 trunks, which are all about 30–60 cm (12–24 in) in diameter.

[2] The leaves are glossy green,[3] alternate (arranged), hairless with slender leafstalks of about 3–5 cm (1–2 in) long.

They are broad and rounded at the base, edges are smooth (and not toothed), and the upper surface is shiny dark green with visible side veining and are paler underneath.

The females have 2–3 scales or bracts at the base and narrow greenish tubular calyx about 6 mm long, which is finely hairy and fragrant.

It has about 20 very small sterile stamens inside the tube and a pistil with a narrow ovary, slender style and enlarged fringed stigma.

The fruit (or seed capsule), is cylindrical, about 4 cm (2 in) long and very narrow, widest below the middle, composed of enlarged calyx with lobes at the apex and many faint lines and enclosing the narrow 1 seeded fruit (or achene) with a style at the apex.

[3] The wood or timber is unused (by natives and woodworkers) and is whitish, soft, very lightweight and porous.

[2][3] The genus name of Rockia is in honour of Joseph Rock (1884–1962), an Austrian-American botanist, explorer, geographer, linguist, ethnographer and photographer.