Asa Gray's report on the botany of the Wilkes Expedition, with plates illustrating plants collected by the first scientific expedition conducted by the United States Navy. Report is specifically on the "phanerogamia", seed plants or flowering plants collected during the four year voyage. Gray was one of the most acclaimed botanists of his time. Not on the expedition itself, he was afterwards asked to study the gathered specimens and produce this report, which took him 3 years. At first Gray planned on a two-volume text report and an atlas with 300 folio plates. Eventually it was whittled down to one large text volume and this atlas with 100 plates drawn by the talented botanical artist Isaac Sprague. The specimens come primarily from throughout the Pacific Rim eg. Hawaii, Singapore, Philippines, Australia, New Zealand and several countries in South America, mainly Chile and Brazil. Title page of this volume states "By Authority of Congress." Total number of volumes published was 24. Spine of this book states it is Vol. XV. This is the official version of the report, as published by Sherman & Son of Philadelphia in an edition of only 100 copies each of text and plates, making this a scarce volume indeed. An official edition was issued by Putnam of New York in an edition of 150 copies. Either edition is now rare on the market as most were intended for research libraries.