CHROMOSOME NUMBERS IN UMBELLIFERAE. V.

Chromosome numbers are reported for 167 collections representing 100 taxa of Umbelliferae. More than four-fifths of the counts apply to members of subfamilies Hydrocotyloideae (29) and Saniculoideae (50); the remaining 21 belong to Apioideae. Chromosome numbers of plants belonging to 68 taxa are published here for the first time; chromosome numbers are verified for 23 taxa; and chromosome numbers differing from those published previously are reported in nine instances. No chromosome counts have previously been reported for 19 of the genera included. Polyploidy has been established for Azorella, Mulinum, Coaxana, Enantiophylla, and Zozimia. THE ORIGINAL FORMAT for this series of papers reflected the view that each taxon could have its chromosome number recorded once and for all. Thus, each paper of the series was planned to include 100 hitherto unreported chromosome numbers of different taxonomic entities. It quickly became apparent that this scheme was insufficiently flexible to allow for the variation in chromosome number found to occur in many taxa and did not permit the recording of important cytological data on different geographical populations of the same taxon, some of them on different continents. The doctrine of "one taxon, one chromosome number" has proved to be a gross oversimplification! We have gradually been altering our procedure to permit presentation of numbers at variance with our own earlier reports and those of other authors, and to allow for a richer geographical sampling, particularly with regard to Latin America. We continue to report on the genus Eryngium in somewhat greater detail because of the cytological diversity revealed in this cosmopolitan group. We have not figured a chromosome count unless it appears to be new or unless it differs from one hitherto published. A voucher specimen for each report is preserved. Most of these Recelved for publication 3 February 1971. Mr. Constance wishes to express his appreciation to the National Science Foundation (Grant GB-6741), to I. N. T. A. , Instituto de Botinica Agricola, Castelar, Argentina, and to The Regents, University of California, for enabling him to conduct field work in Argentina in 1967-68, and to the many Argentinian botanists who made this trip an unforgettable experience. The three earlier papers in this series (Bell and Constance, 1957, 1960, 1966) provided a rationale for our program of investigating chromosome numbers in Umbelliferae as well as a series of progress reports. The same general methods of investigation and presentation have been emp oyed in this fourth installment except that we have felt it unnecessary to illustrate all counts reported. The great majority of the counts offered here have been made by Mr. Chuang. vouchers are housed in the Herbarium of the University of California, Berkeley, with duplicates in the Herbarium of the University of North Carolina, Chapel Hill, or at Illinois State University, Normal. The vouchers for counts of Tierra del Fuegan plants, made from buds furnished by Mrs. Goodall of Ushuaia, are in her personal collection, surely the most southerly herbarium in the world. Whereas the last paper dealt primarily with data obtained by Mr. Bell and his associates during the course of field work in Mexico, the present one combines results obtained from both American continents and elsewhere and emphasizes Hydrocotyloideae and Saniculoideae. We are very grateful for the generous efforts of the many contributors listed. This particular paper has benefitted especially from the contributions of Dennis E. Breedlove, Robert W. Cruden, Rae Natalie Goodall, Antonio Krapovickas and Carmen Cristobal de Krapovickas, Reid Moran, T. Myndel Pedersen, P. Raulino Reitz, Hans Sleumer, Otto T. Solbrig, and the late Elwood Molseed. The staff of the Jardmn Botanico, Montevideo, Uruguay, has been especially generous with significant material. Through the courtesy of Paul C. Hutchison, who organized the trip and collected the material, and of Marion S. Cave, who made the counts, we are privileged to publish data obtained by the 7th University of California Botanical Garden Expedition to the Andes, 1963-64. We have, of course, freely availed ourselves of botanical garden seed lists, and express our appreciation to these rich sources of material. More than 1,250 seed samples of Umbelliferae have now been planted and grown in the University of California Botanical Garden in the past ten years. (The "Constance numbers" below 3,000 in the third column of the table were assigned to materials furnished by the senior author that were grown in the Garden.) It is