Santalum pyrularium is an evergreen small or shrubby tree, usually reaching 1–5 meters high. It has single or multiple stems. The leaves are simple and opposite, with blades that are narrow to broadly elliptic, ovate, or oblong (rarely conduplicate–falcate), measuring (3.6–)5.4–7.8(–9.4) cm long and (1.2–)2.1–3.2 (–3.8) cm wide. The leaf apex ranges from acute to obtuse (rarely acuminate), and the base is cuneate or rounded. The lower surface is more glaucous and not much paler than the upper surface, with the overall color being medium to dark green and the texture chartaceous to coriaceous. The margins are entire and flat (rarely wavy). The lateral veins are apparent on both surfaces and can be yellowish to bright purple. Petioles are (5.9–)7.8–12.6(–15.7) mm long, and stipules are absent. The flowers are in cymes, sparse, and axillary (rarely terminal), with pedicels (1.0–)1.1–2.7 (–3.1) mm long and bracts 1–4 mm long, not persistent. The flowers are bisexual (perfect). The corolla consists of 4 petals, which can be cream to purple throughout or greenish with a purple interior. The floral tubes are campanulate to cylindrical, measuring 3.6–8.5(–13.0) mm long and (2.6–)2.9–4.3(–4.4) mm wide, with a vertical keel below each lobe. The petals are concave with thickened margins, papillate, and measure (3.4–)4.2–5.6(–5.8) mm long and (2.0–)2.4–3.3 (–3.7) mm wide. There are four stamens, with hairs proximal to the filaments (rarely distal). The ovary is partly inferior (approx. 2/3), with three stigma lobes. The fruit is a drupe, elliptic in shape with a subapical ring, measuring 15–22 mm long. The seeds are muricate, with a pointed beak on one end. It is found in mesic (summer dry) forests and occasionally in wet forest communities and bog margins between 270-1,400 meters.