AASP Primary Records Program

A. Orville Dahl 1910 - 2003

A. Orville Dahl received his doctorate in botanical cytology and geneticsfrom the University of Minnesota in 1938. His graduate studies there includedlong-term analyses of atmospheric pollen in relation to pollinosis.

After completing his graduate work, he served as Instructor of Biologyfor six years at Harvard University where, in his stimulating associationwith Irving W. Bailey, he conducted an intensive survey of pollen morphologyof the Icacinaceae. From Harvard, he returned to the University of Minnesotaas Professor where, for a decade, he was Chairman of the Botany Department.Orville held a Professorship of Botany at the University of Pennsylvania,Philadelphia from 1967 until 1978 when he was named Professor emeritusfollowing mandatory retirement.

He was one of the pioneers in atmospheric pollen and spore studies andmaintained collection stations for more than 30 years. His interest inpollen morphology, beginning in a serious way with work on the Icacinaceae,was continued with many species throughout his life. Emphasis, especiallyin his teaching, was on living or well-preserved microspores and theirdevelopment into pollen grains. His interest was in teaching what laterwould be called pollen biology. He and other broadly experienced botanistsand biologists, among them Johs. Iversen, Knut Faegri, Stanley Cain, A.Traverse, E.S.Barghoorn, J. William Schopf, L.R.Wilson, influenced a generationof men and women who contributed greatly to studies of pollen and sporedevelopment, many aspects of archeology, palaeoecology and hydrocarbonexploration. Micrographs of Orville's thin sections of Tradescantia pollenare the first transmission electron illustrations of sectioned pollen.

For many years Orville made histological and cytological observationsas part of a NASA space biology program. He studied the effect of gravitationfields on Arabidopsis and its morphologenesis in controlled G-environments.He also studied the vascularization of the primary flowering stem undercontrolled G-environments.

Orville spent many summers in the Stockholm area living with specialpleasure, when possible, in Vaxholm in the Stockholm Archipelago and commutingto Stockholm by boat. He was an avid horticulturist and filled our seasidegarden with exotic plants. Three of the varieties of grapes that he plantedhave survived ten or more of our winters and now form an extensive arbor.

Orville was welcomed as a visiting scientist at Stockholm Universitywhere we worked together in the Botany Department on many long-term projects.

Orville died this year on January 21st at Lakeshore Lutheran Home, Duluth,Minnesota. He would have been 93 on April 18th. Shortly before his deathhe spent a good Christmas in the company of his niece Karen, her husbandDr. Thomas Holm, their three sons and their families.

Orville much appreciated the good things in life — classical music,art, good food and visiting new places. He was a generous, kindly and loyalfriend, a source of inspiration and information.

- John and Joanne Rowley

Some Published Papers:

Dahl, A. O. and Ellis, R. V. 1942. The pollen concentration of the atmosphere.Public Health Reports 57: 369-377.

Fernández-Morán, H. and Dahl, A. O. 1952. Electron microscopyof ultrathin frozen sections of pollen grains. Science 116: 465-467.

Dahl, A. O. 1965. Pollen physiology and fertilization. Science. 147:602.

Dahl, A. O., Rowley, J. R., Stein, O. L. and Wegstedt, L. 1957. Theintracelular distribution of mass during ontogeny lof pollen in TradescantiaL. Experimental Cell Research 13: 31-46.

Dahl, A. O. 1962. The story of pollination. Science 136: 528.

Dahl, A. O. 1964. The fine structure of pollen. Proc. 10th InternationalBotanical Congress, Edinburgh. p. 221.

Rowley, J. R. , Dahl, A.O. and Skvarla, J. J. 1973. Localization ofATPase activity in pollen grains. Norwegian Journal of Botany 20: 31-50.

Dahl, A.O. 1976. A commentary on the evolutionary significance of theexine. Edited by I.K.Ferguson and J.Muller. Linnean Society Symposium SeriesNo. 1: 561-571.

Brown, A. H., Dahl, A.O. and Chapman, D. K. 1976. Morphology of Arabidopsisgrown under chronic centrifugation and on the clinostat. Plant Physiology57: 358-364.

Brown, A. H., O'Dowd, P.O., Loercher, L. Kuniewicz, R. and Dahl, A.O. 1979. Serendipitous solution to the problem of culturing Arabidopsisplants in seled containers for spaceflights of long duration. (COSPAR)Life Sciences and Space Research 17: 37-43.

Rowley, J. R., Dahl, A. O., Walles, B. and Huynh, K.-L. 1983. Viscinthreads considered as connective structures between pollen grains and tapetalcells. Proceedings of the 7th International Symposium of Fertilizationand Embryotgenesis in Ovulated Plants. High Tatra, Slovak Academy of Sciences,Veda, Bratislava: 89-92.

Dahl, A. O. 1986. Observation on pollen development in Arabidopsisunder gravitationally controlled environments. Pollen and Spores: Formand Function. Edited by S.Blackmore and I.K.Ferguson. Linnean Society SymposiumSeries No. 12:49-59.

Dahl, A. O. and Rowley, J. R. 1991. Microspore development in Calluna(Ericaceae). Exine formation. Annales Sciences Naturellers, Botanique,Paris, 13 serie 11: 155-176.