Hipólito Ruiz López (August 8, 1754, in Belorado, Burgos, Spain – 1816, in Madrid), or Hipólito Ruiz, was a Spanish botanist known for researching the floras of Peru and Chile during an expedition under Carlos III from 1777 to 1788. During the reign of Carlos III, three major botanical expeditions were sent to the New World; Ruiz and José Antonio Pavón Jiménez were the botanists for the first of these expeditions, to Peru and Chile.
After studying Latin with an uncle who was a priest, at the age of 14 Ruiz López went to Madrid to study logic, physics, chemistry and pharmacology. He also studied botany at the Migas Calientes Botanical Gardens (now the Real Jardín Botánico de Madrid), under the supervision of Casimiro Gómez Ortega (1741–1818) and Antonio Palau Verdera (1734–1793).
Ruiz had not yet completed his pharmacology studies when he was named the head botanist of the expedition. The French physician Joseph Dombey was named as his assistant, and the pharmacologist José Antonio Pavón y Jimenez was also appointed. Completing the expedition were the botanical illustrators Joseph Bonete and Isidro Gálvez.
The expedition sailed from Cádiz in 1777, arriving at Lima in April 1778. They explored throughout Peru and Chile for ten years (1778–1788), collecting specimens. The expedition collected 3,000 specimens of plants and made 2,500 life-sized botanical illustrations. When they returned to Spain they brought back a great many living plants.
One of the medical remedies brought back by this expedition was the boiled spouts of the quisoar plant, Buddleja incana, which was used to cure colds or, mixed with urine, to alleviate toothache.
The collections arrived in Cádiz in good order (for the most part) in 1788, and were deposited in the Real Jardín Botánico de Madrid and in the Gabinete de Historia Natural, the precursor of the Museum of Natural History. The discoveries included about 150 new genera and 500 new species, which still retain the names given them by Ruiz and Pavón. Unfortunately, a part of the collection consisting of 53 crates with 800 illustrations, dried plants, seeds, resins and minerals was lost when the ship transporting it was wrecked on the coast of Portugal.