A French botanist and traveller, born at Rochelle; companion of Alexander von Humboldt in his S. American scientific explorations; brought home a large collection of plants, thousands of species of them new to Europe; went out again to America, arrested by Dr. Francia in Paraguay as a spy, kept prisoner there for about nine years; released, settled in the prov. of Corrientes, where he died; wrote several works bearing on plants (1773-1858).