Metrosideros polymorpha var. pseudorugosa is a shrub with characteristic bark that is usually rough and fissured, peeling away in thick flakes and sometimes smooth, peeling in long, thin strips. The vegetative buds are obovoid in shape. The leaves are simple and opposite, with blade shapes that range from obovate to orbicular and sometimes elliptic, broadly ovate, or ovate, measuring 1–8 cm in length and 1–5.5 cm in width. The apex is rounded or sometimes shifts to obtuse or acute, while the base varies from cuneate to cordate. The upper surfaces are glabrous, while the lower surfaces may be glabrous, woolly, or display appressed pubescence. Margins are entirely revolute to flat, featuring several pairs of raised veins emanating from the base. Petioles are typically short, usually much less than ⅓ the length of the blades, measuring 1–16 mm in length and 1–3 mm in width. Stipules are either vestigial or absent. The flowers are arranged in inflorescences consisting of 2–5 pairs of cymules, which can be glabrous, appressed, or woolly pubescent; peduncles measure 7–18 mm in length and 1–3 mm in width, while pedicels range from 2–8 mm long and 1–2 mm wide. Bracts are broadly ovate to suborbicular, measuring 5–10 mm long and 3–5 mm wide; the hypanthium is 3–7 mm high and 3–8 mm wide. The flowers, displaying colors from red to pink and orange, are bisexual (perfect) and actinomorphic (radially symmetric). Sepals are rounded to triangular, measuring 1.5–4 mm in length and 1.5–3 mm in width. Petals are obovate to orbicular, measuring 2.5–5 mm long and 2–4.5 mm wide. Stamens range from 1–3 cm in length. The ovary is nearly superior, with a style length of 1.3–3 cm. The fruits are capsules that are slightly included to exerted, with a fruiting hypanthium measuring 3–8 mm in length and width, which can be either pubescent or glabrous. It is found in high-elevation bogs.