Vitex rotundifolia is a low, branched shrub with procumbent stems that often root at the nodes, forming several-meter-diameter mats. In contrast, side branches ascend to erect, typically measuring 10–30 cm long. Its leaves are simple or rarely compound (palmate), opposite or whorled (3 per node), with blades ranging from obovate to suborbicular, 2–6.5 cm long and 1–4.5 cm wide. The leaves feature a rounded apex, with the base attenuating into petioles up to 1 cm long. The upper surfaces are pale green and densely puberulent, while the lower surfaces are grayish white and densely tomentose, emitting a sage-like odor when crushed. The leaves have entire margins and lack stipules. Flowers are typically grouped in threes within narrow paniculate inflorescences 3–7 cm long, exhibiting a white or grayish tomentose appearance with linear bracteoles 1–2 mm long. The bisexual (perfect) flowers feature a cup-shaped calyx that is 4–4.5 mm long, enlarging slightly in fruit to about 5 mm, and a bilabiate, bluish-purple corolla that is narrowly funnelform and densely puberulent. The stamens are exserted from the corolla tube, with anthers that open by longitudinal slits. The ovary is superior, initially 2-celled but eventually 4-celled, with one ovule per cell and a style approximately 12 mm long. The fruit is a fleshy, 4-celled drupe that turns from green to yellow and red-tinged, eventually bluish-black at maturity, and measures about 6 mm in diameter. Each cell contains one obovate or oblong seed without endosperm. It typically inhabits sandy beaches, shores, and dunes between 0-15 meters.