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Karl Sax (1892-1973) papers, 1938-2001.


The papers of Karl Sax were compiled primarily during his tenure as Director of the Arnold Arboretum from 1946 to 1954, though their contents reflect both his administrative work and his research in cytology, horticulture, and genetics. Originally from Washington, Sax spent many years studying and researching in Maine and Massachusetts. Sax’s tenure at the Arboretum was filled with challenges, as his administration dealt with both the controversial “Bailey Plan” and redeveloping a collection neglected during World War II. Sax’s collection spans the years 1938-2001, covering his time as a professor and as director of the Arnold Arboretum and including collection-related correspondence from Edward A. Sax.


  • 1938-2001

General Physical Description note

(23 boxes and 2 oversize folders)

(23 boxes and 2 oversize folders)

Terms of Access

This collection is open for research. Researchers seeking to examine archival materials are strongly encouraged to make an appointment. The Director, or an office of origin, may place restrictions on the use of some or all of its records. The extent and length of the restriction will be determined by the Director, office of origin, and the Archivist and will be enforced equally for all researchers.

Terms of Use

The copyright is held by The President and Fellows of Harvard College for the Arnold Arboretum Archives of Harvard University. The copyright on some materials in the collection may be held by the original author or the author's heirs or assigns. Researchers are responsible for obtaining written permission from the holder(s) of copyright and the Arnold Arboretum Archives prior to publishing any quotations or images from materials in this collection.

Photocopies may be made at the discretion of the Arnold Arboretum Archives staff. Permission to make photocopies does not constitute permission to reproduce or publish materials outside the bounds of the fair use guidelines.


5 linear feet
This collection spans the years from 1938-1959, and primarily reflects Sax's research in cytology, horticulture, and genetics, but also includes his administrative work as director of the Arnold Arboretum from 1946-1954. Sax's objections to the Bailey Plan are noted in letters that date from 1949 to 1954. In addition to correspondence, there are logbooks of detailed data on experiments, notes on nursery plants, a crossing index, cytological reviews, Arboretum plant accession books 1939-1942, and records with notes on fertilization, planting, and plant propagation. In 2011, descendants of Sax donated several certificates and pieces of correspondence to the collection.

Biographical note

Karl Sax served as the third director of the Arnold Arboretum (1946-1954). Both a research scientist and an administrator, Dr. Sax had the challenging responsibility of leading the Arboretum through a difficult transitional period. His administration dealt with the results of deferred maintenance of the living collection due to the labor and materials shortages caused by World War II. Also during his tenure as director, Sax had to address the controversy caused by the “Bailey Plan” to reorganize Harvard's Botany Department and remove resources from the Arboretum's Hunnewell Building and library by transferring herbarium specimens and books to a new building in Cambridge. Arboretum funds would also be used in the Department of Biology, and the interest in horticulture and the living collections would be lessened. Many people connected with the Arboretum were concerned that this move would compromise the work of the institution. In 1953, the Association for the Arnold Arboretum was incorporated and initiated a suit questioning whether the proposed organizational changes, with the funds of the Arboretum used within the Department of Biology, would be a breach of the trust under which the Arboretum was founded. Dr. Sax did not approve of the reorganization plan and refused to implement it without legal review. He resigned from his administrative duties in 1954.

Karl Sax (1892-1973) was born in Spokane, Washington and received a B. S. in agriculture from Washington State in 1916. He earned an M.A. in biology from the Bussey Institution of Harvard University in 1917 and served in the US Army from 1917 to 1919. Sax joined the staff of the Agricultural Experiment Station at the University of Maine, and earned a D.Sc. from the Bussey Institution in 1922 while serving at Maine until 1928. In 1928, Dr. Sax was appointed Associate Professor of Plant Cytology at the Arnold Arboretum, faculty at the Bussey Institution, and became a full professor in 1936. When Elmer D. Merrill retired as director of the Arnold Arboretum in 1946, Sax was appointed acting director and director the following year. After stepping down as director in 1954, he remained as Professor of Biology until his retirement in 1959.

Dr. Sax was a pioneer researcher in cytology and genetics, focusing on chromosomal studies and their application to cross breeding of agricultural varieties. His studies of the methods of chromosome breakage used experimental exposure to X-rays and other types of radiation. His influential 1938 paper, "Chromosome aberrations induced by X-rays" opened up a new area of investigation subsequently developed by other scientists. His contributions in horticultural plant breeding produced many hybrid plants, which he named. After Sax left Harvard in 1954 he served as Visiting Professor of Botany at Yale University and spent the following year in Oxford, England as recipient of a Guggenheim Fellowship

Sax became concerned about the problems of feeding an ever-expanding world population. He was a spokesman for the Planned Parenthood organization, and wrote a book on population problems, Standing Room Only. In his retirement years, Sax received grants from the National Institutes of Health to support his study of the radiometric effects of common products like coffee, cola drinks, drugs, and food additives.

In 1987 the National Academy of Sciences published a biographical memoir of Dr. Sax written by Carl P. Swanson and Norman H. Giles.

Sax wrote many articles for the Arboretum’s journal Arnoldia which are available to read online:
Missing Title
  1. “Plant Hybrids.” Arnoldia 3: Vol. 5, 1931 (
  2. “Flowering Habits of Trees and Shrubs.” Arnoldia 3: Vol. 6, 1932 (
  3. “Plant Breeding at the Arnold Arboretum.” Arnoldia Vol. 7, No. 2, 1947 (
  4. “The Bussey Institution.” Arnoldia Vol. 7, No. 3, 1947 (
  5. “Rootstocks for Lilacs.” Arnoldia Vol. 10, No. 9, 1950 (
  6. “Dwarf Trees.” Arnoldia Vol. 10, No. 12, 1950 (
  7. “Plant Breeding at the Arnold Arboretum.” Arnoldia Vol. 15, No. 2, 1955 (
  8. “Paste the Poison Ivy.” Arnoldia Vol. 16, No. 2, 1956 (
  9. “The Juvenile Characters of Trees and Shrubs.” Arnoldia Vol. 18, No. 1, 1958 (

Arrangement note

Missing Title
  1. Series I: Biographical Material
  2. Series II: Correspondence
  3. Series III: Manuscripts
  4. Series IV: Plant Records and Research


The Karl Sax papers were compiled during Sax’s tenure at the Arnold Arboretum. This collection was then transferred from the Arnold Arboretum’s departmental holdings to the Arboretum’s Archives in 1986 when the Archive was established. Supplemental correspondence from Edward A. Sax to Robert Cook in 2001 was added in 2004. In 2011, descendants of Sax donated several certificates and pieces of correspondence to the collection.

Related Archival Materials note

For additional material related to the Arnold Arboretum Controversy, see I A-3 “The Controversy” records, 1945-1966.

Processing Information note

June 2003, revised 2005. Updated April 2011, Kayleigh Hinckley. Revised April 2012, Liz Francis.
Karl Sax (1892-1973) papers, 1938-2001.
Finding aid prepared by Liz Francis

Repository Details

Part of the Arnold Arboretum Archives Repository

The Arnold Arboretum Horticultural Library is a specialized collection devoted to the study of temperate woody plants. We collect works on botany, horticulture, floras, urban forestry and taxonomy. The library contains more than 25,000 volumes and 40,000 photographs, and includes an archive that both documents the Arboretum's history and is a repository for 19th, 20th, and 21st century horticultural and botanical collections.

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