Exocarpos gaudichaudii presents as small, polygamous trees or sometimes shrubs, typically standing 2–5 meters tall, though they can reach up to 7 meters. The stems are green, densely branched toward the tips, stiff, and erect. The leaves are simple, primarily scale-like, with a few foliaceous ones interspersed, and are sessile. When foliaceous, the leaves are alternately arranged, rarely sub-opposite, and range from narrowly to broadly elliptic or obovate, measuring 38–60 mm in length and 16–30 mm in width. The base is attenuate with entire margins, and the secondary veins arise at the leaf base, running parallel to the midrib. Floral characteristics include terminal and axillary spikes featuring bisexual (perfect) and unisexual flowers on polygamodioecious plants (one plant has female and bisexual flowers, and another has male and bisexual flowers), with no calyx present. The corolla comprises 4–6 green to yellowish green petals, each 0.5–1 mm long. The stamens number 4–5 and are uniform in shape. The ovary is partly superior, embedded in a fleshy receptacle, with one ovule embedded in the placenta and scarcely differentiated from it, appearing as a single massive ovule. The fruit is a drupe, green to greenish-yellow at maturity, ellipsoid, and measures 8–10 mm long, with the exposed portion above the receptacle being 5–7 mm long. The rounded apex features a small terminal beak or three inconspicuous indentations and is partially embedded in a bright red, fleshy receptacle. It is found on ridges in mesic forests and shrublands, occasionally venturing into wet forests’ open, drier areas between 300-920 meters, reaching up to 1,550 meters on Hawai’i Island and as low as 250 meters on Lānaʻi.