Proceedings of the American Academy of Arts and Sciences.

VOL. XLII. No. 1.- MAY, 1906.

CONTRIBUTIONS FROM THE GRAY HERBARIUM OF HARVARD UNIVERSITY.

NEW SERIES. No. XXXII.

STUDIES IN THE EUPATORIEAE.

I. Revision of the Genus Piqueria.

II. Revision of the Genus Ophryosporus.

III. The Genus Helogyne and its Synonyms.

IV. Diagnoses and Synonymy of Eupatorieae and of certain other Compositae which have been classed with them.

BY B. L. ROBINSON.

CONTRIBUTIONS FROM THE GRAY HERBARIUM OF HARVARD.

UNIVERSITY, NEW SERIES, NO. XXXII.

STUDIES IN THE EUPATORIEAE.

BY B. L. ROBINSON.

Presented March 14, 1906. Received February 21, 1906.

INTRODUCTORY.

DURING the summer of 1905 the writer spent some weeks in visiting several of the larger herbaria of Europe in order to examine and photograph plants not hitherto authoritatively represented in the Gray Herbarium. In the course of this work considerable attention was given to the tropical American species of the great genus Eupatorium and several allied genera. As must be expected in all such large and difficult groups, which have not been subjected to recent revision, the study of the type-specimens of several hundred species has yielded much new information on the synonymy and proper classification of the group. The collections examined were: (1) the herbarium of the Museum of Natural History in Paris, where the herbaria of Jussieu, Lamarck, and Michaux were consulted, and special attention given to an admirably preserved and well-nigh complete set of the tropical American plants collected by Humboldt and Bonpland and critically described by Kunth in the Nova Genera et Species; (2) the rich private herbarium of the DeCandolle family in Geneva, including the invaluable Prodromus types; (3) the herbarium of the Imperial Museum of Natural History at Vienna, noteworthy among other ways by containing the fullest series available of the species of Jacquin and an excellent series of the plants of Pohl and species of Poeppig and Endlicher; (4) the herbarium of the Royal Botanical Museum at Berlin, remarkably rich in South American as well as in Old World types and in the study of Eupatorieae specially noteworthy by exhibiting to its fullest extent the recent critical work of Dr. Hieronymus ; (5) Professor Urban's large and carefully selected West Indian herbarium; (6) the herbarium of the Botanical Museum of the University of Copenhagen, containing, together with much other material of interest, the extant types of Vahl; (7) the herbarium of the Linnean.

Society of London, where special attention was given to the types of Linnaeus filius and of Sir James Edward Smith; (8) the herbarium of the Royal Botanical Gardens at Kew, noteworthy to the student of the Eupatorieae by exhibiting the very numerous Brazilian types of Gardner, Hooker & Arnott, Bentham, and Baker, as well as the Mexican work of Hemsley; (9) the herbarium of the British Museum of Natural History, including, among many other specimens of high interest, the plants of Clayton, Walter, and Philip Miller.

The writer would here express his sincere thanks to all those in charge of these herbaria for their cordial hospitality, uniform courtesy, and valuable aid during his researches. He is also indebted to Messrs. Oakes Ames and A. A. Eaton for several excellent photographs of type-specimens at Paris, to Mr. H. Hua for a critical comparison of a Peruvian Piqueria in the herbarium of Jussieu, to Miss Mary A. Day, Librarian of the Gray Herbarium, for bibliographical assistance, and to Mr. F. V. Coville and Dr. J. N. Rose for the loan of the material of Piqueria belonging to the United States National Museum.

About four hundred photographs of types were taken in the European herbaria, some important exchanges effected, and many notes and sketches prepared, which it is hoped may form an accurate basis for considerable work on the group concerned. In the present paper only a small part of the results of the summer's investigation can be presented, but as any complete or monographic treatment of so large a group must be delayed for a considerable time, it seems best to record such identities and synonymy as can be at once stated with definiteness, in order that certain traditional errors may not become more fixed by longer usage. The nomenclature adopted is that recommended by the international congress at Vienna.

I. REVISION OF THE GENUS PIQUERIA.

Piqueria is the typical genus of the Piquerinae, a small subtribe of the Eupatorieae. The Piquerinae are chiefly marked by their blunt anthers, which entirely lack the more or less expanded, oblong, or lanceolate prolongation of the connective, which is present almost without exception in other Compositae. In this subtribe the genus Piqueria is characterized by a complete absence or very rudimentary development of its pappus. Its natural affinities are obviously on one hand with Ophryosporus, which scarcely differs save in the presence of a well-developed setose pappus, and on the other hand with Alomia and Ageratum, which are habitally approached by the species of Piqueria belonging to the subgenus Phalacraea. Geographically Piqueria extends from the Sierras of northern Mexico through central