Alepidea macowani is a robust, erect, perennial herb that can grow up to 1 m in height. The stem is hollow, grooved and branched, with numerous, slightly fleshy, large, aromatic rootstocks arising from an underground rhizome, 15 to 40 mm in diameter. The roots are thick, 2–5 mm in diameter, and swollen at the base. The leaves are triangular and simple, typically numbering between 10 and 20. They are mostly found at the base, forming a loose rosette, although some grow along the stem. Leaf sizes range from 100–380 mm in length and 20–135 mm in width, with shapes varying from elongated and spoon-shaped to oval or broad. The leaves are smooth, with reticulate veins that are slightly depressed on the upper surface, and the tips are either rounded or pointed. The leaf margins are variable, toothed and lobed, with 1–10 coarse teeth per lobe and pointed tips. The leaves narrow at the base into thin, membranous wings, 1–7 mm wide, along smooth, ribbed stalks. The inflorescence is located at the tip of a long scape (flower stalk), which arises directly from the roots and can grow up to 1.8 m high. The inflorescence is much branched below the middle, racemose or paniculate, with lateral branches that are short or long in the upper parts, and with prominent fine hairs on the upper portions. The star-shaped flower heads, approximately 20 mm in diameter, consist of many small flowers surrounded by five large, petal-like bracts. These bracts are white to pale yellow on top, green below, and sometimes have fine hairs at the base. The bracts are triangular with small alternating teeth. Flowering occurs from late summer to autumn (January–April). The fruits are small, egg-shaped schizocarps (dry fruits that split into single-seeded parts), smooth, with one flat surface and the opposite curved, turning dark brown when ripe.