Cyrtandra kaulantha is a shrub typically growing from several stems from a horizontal base. These erect stems range from 1 to 3 meters long and may be unbranched or occasionally have short lateral branches. Both erect and horizontal stems produce adventitious roots and are covered with pubescent multicellular hairs or can be smooth (glabrate). The leaves are simple, opposite, and decussate, clustering on the upper 3 to 6 nodes. Each leaf at a node is slightly unequal and symmetrical, ranging from 30 to 60 cm in length and 10 to 24 cm in width, with oblanceolate to elliptic-oblanceolate shapes. The leaf apex is acuminate, and the base is long-attenuate. The upper surfaces of the leaves are sparsely pilose along the veins, while the lower surfaces are sparsely to moderately short-pilose, especially along the veins. The leaves are fleshy, drying to a thin, chartaceous texture, with serrulate margins and slightly raised veins on the lower surface. The leaves are sessile, without stipules. The flowers occur in dense compound cymes, typically located on the lower third of the erect stems, often at the base, and sometimes on horizontal stems or adventitious roots. The inflorescences are covered in moderately appressed dark brown pilose hairs, with peduncles 2–6 mm long and pedicels 3–11 mm long. The flowers are bisexual (perfect) and feature a zygomorphic (bilaterally symmetric), short-fusiform calyx in the bud, which becomes 16–23 mm long at anthesis. The corolla is usually bilabiate and white, with a narrow funnelform tube that is curved and 17–22 mm long. The stamens are inserted about halfway up the corolla tube, with two upper fertile stamens and the rest being staminodial. The ovary is superior, oblong-ovoid, and has a parietal placentation. The fruit is a fleshy or firm berry, ovoid-ellipsoid to oblong-ellipsoid, and 1.4–1.8 cm long, often with a persistent stylar beak. The seeds are numerous and ellipsoid, with a reticulate surface. It is commonly found in streambeds and on talus slopes within a few mesic valleys between 240-320 meters.