Perennials, 10–50(–80+) cm. Stems prostrate or decumbent. Leaves mostly opposite; petioles 5–25 mm; blades rounded-deltate to ovate or elliptic, 20–35+ × 10–30+ mm, 2–3-pinnately lobed, bases cuneate, ultimate margins entire or toothed, abaxial and adaxial faces strigillose. Pistillate heads clustered, proximal to staminates; florets 1. Staminate heads: peduncles 1–2 mm; involucres obliquely cup-shaped, 2–3+ mm diam., strigillose; florets 5–20+. Burs: bodies ± pyriform, 1–2 mm, ± strigillose, spines or tubercles 0–5+, near middles or distal, stoutly conic, 0.1–0.5+ mm, tips straight. 2n = 104.
Ambrosia hispida is an herbaceous perennial, growing along the ground rarely above 20 cm in height, and typically forming mats. The leaves are arranged oppositely, to 9 cm in length and pinnately compound, dividing 2 or 3 times creating a lacy appearance. The leaflets are lanceolate, with an acuminate leaf apex and deeply serrated leaf margin. The vegetative structures are covered with a hispid pubescence that gives the plant a light green to gray appearance. The incomplete, imperfect, monoecious flowers are arranged in racemes of heads subtended an involucre made of 1 series of phyllaries. The actinomorphic flowers occur in the center of the head, each subtended by a bract. The staminate flowers have 5 sepals, 5 unfused stamens, and a non-functional ovary. The carpellate flowers have no perianth or stamens and a single superior ovary that becomes an achene at maturity. The achenes are covered with pubescence and tubercles.
Ambrosia hispida is widely used in the Bahamas for a variety of illness categories including to treat colds and flu, gastrointestinal issues (increasing appetite, diarrhea, indigestion and vomiting), as well as dermatological problems (blisters and general skin irritation). Elsewhere in the Caribbean it is used to treat worms and high blood pressure.