Delissea argutidentata is an unbranched treelet or tree that grows to a height of 1–9 meters. The stems are erect or ascending, usually unbranched, and measure 7–20 mm in diameter towards the apex. They are light gray or brown, unarmed, glabrous, with numerous helically arranged leaf scars, and exude white, viscous latex. The leaves are simple, alternate, well-dispersed on the distal stem, or congested into apical rosettes. The blades are narrowly elliptic, 12.5–25 cm long, and 3.5–7.0 cm wide, with an acute or cuspidate apex and a cuneate or attenuate base. The surfaces are glabrous, fleshy when fresh, and membranous to somewhat chartaceous when dry. The margins are serrate or serrulate and undulate. The leaves are pinnately veined and have 5–14 cm long petioles and 1/3–2/3 as long as the lamina. Stipules are absent. The flowers are in several axillary, racemose inflorescences per stem, with 5–15 flowers per raceme. The peduncle and rachis are ascending or spreading, glabrous, with the peduncle measuring 6–25 mm long and the rachis 5–23 mm long. The bracts are triangular or deltate, 0.7–4.0 mm long, and pubescent, persistent, each subtending a pedicel. The pedicels are ascending or spreading, 5–7 mm long, with or without minute knob-like bracteoles at or above the base. The hypanthium is 4.5–7.5 mm long and 3.0-4.8 mm in diameter, obovoid, obconic, or ellipsoid. The flowers are tetracyclic, bisexual (perfect), complete, protandrous, epigynous, resupinate, and pedicellate. The calyx is synsepalous and actinomorphic (radially symmetric), with a tube adnate to the ovary, forming a glabrous hypanthium 1/10–1/3 as long as the corolla. The calyx lobes are 0.9–3.0 mm long, 0.4–1.5 mm wide, glabrous, persistent, distinct, triangular or deltate, and 1/20–1/2 as long as the hypanthium. The corolla is 16–24 mm long, with a tube 9–12 mm long, 1.2–2.0 mm tall at the base, and 1.5–3.5 mm tall above the middle. The dorsal lobes are 7–12 mm long and 0.5–1.1 mm wide, 3/4 as long as the tube. The ventral lobes are 6–10 mm long and 0.5–0.9 mm wide. The corolla is sympetalous, zygomorphic (bilaterally symmetric), bilabiate, greenish (sometimes suffused with purple), and glabrous. The tube is gently curved, 2.3-4.2 mm tall above the middle with a single dorsal knob, and the lobes are 5, linear-triangular, valvate, spreading, equaling or shorter than the tube (rarely somewhat longer), acute or acuminate at the apex, somewhat dimorphic, with the dorsal pair longer and the ventral three usually connate for 1/4–1/2 their length. The stamens are 5, syngenesious, antisepalous, exserted, emerging from the corolla above (rarely between) the dorsal lobes. The filaments are connate, free from the corolla, and inserted on the rim of the hypanthium. The filament tube is 13–18 mm long, and the anthers are connate, dithecal, dehiscing introrsely and longitudinally, 1/8–2/3 as long as the filament tube, with the dorsal three longer than the ventral pair. The dorsal anthers are 4.5–8.0 mm long, 1/3–1/2 as long as the filament tube, and the ventral anthers are 3.5–6.5 mm long, with tufts of hairs 1.0–1.9 mm long at the apex. The anther tube is 1.5–2 mm in diameter, and the surface of the tube is glabrous or sparsely pubescent. The pollen is tricolporate, prolate, and ellipsoidal. The ovary is inferior, 2-loculed, and crowned by an annular nectary, with numerous ovules and axile placentation. The style is slender, terete (cylindrical), with a ring of stiff white hairs near the apex. The stigma is 2-lobed, with the lobes appressed and non-receptive as the style grows through the anther tube, pushing out pollen, after which the stigmas spread and become receptive. The fruit is a small purple fleshy, thin-walled berry, 8–10 mm in diameter, and globose. The seeds are numerous, ~1 mm long, 0.7–0.8 mm wide, grayish white, ellipsoid, compressed, dull, and transversely rugose. It is found in mesic forests between 915–1585 m.