To celebrate Father’s Day 2019, here are three photographs of famous fathers and sons in biology and physics.

The careers of Henry Nehling and his son Arlo, pictured together at a 1927 botany conference at Cornell University, epitomize the academic and applied sides of biology. Henry Nehrling (1853-1929) had begun his scientific career as an ornithologist, and became one of the founders of the American Ornithological Society in 1883. By the end of his career, he was one of the most celebrated horticulturists in the United States, and had established major gardening operations in Florida. Nehrling collected hundreds of plants around the world, which found their way into American gardens, and hybridized over 1700 varieties of caladiums. In 1928, noted botanist David Grandison Fairchild (1869-1954), representing the Council of the American Genetic Association, presented Nehrling with the Frank N. Meyer Memorial Medal for his distinguished field work and explorations for the U.S. Department of Agriculture's Office of Foreign Plant and Seed Introduction. It was fitting that the award was given at the annual convention of the Florida Federation of Garden Clubs. Henry's son Arno Herbert Nehrling (1886-1974) eventually left his academic post as Professor of Floriculture at Cornell University, and became director of exhibits at the Massachusetts Horticultural Society. Upon his death, the Boston Globe celebrated Arno as "Mr. Flower Show," for the wildly successful spring exhibitions he had managed for over 30 years.

Henry Nehrling (1853-1929), horticulturist, with his son Arno Herbert Nehrling (1886-1974), Assistan

The Cook family had a similarly linked scientific heritage. As a U.S. Department of Agriculture botanist, Orator Fuller Cook, Jr. (1867-1949) also participated in the great plant collecting activities of the early twentieth century. Cook traveled throughout the world to find new plant species, primarily cotton, rubber, and palms. His wife, Alice Carter Cook (1868-1943), whom Orator had met during their college years at Syracuse University, received the first Ph.D. in botany granted to any woman in the United States in 1888. Alice taught for a few years, went on to earn a second degree in botany at Cornell in 1892, and married Orator the following year. Their son, Robert Carter Cook (1898-1991), followed a less traditional path, with little formal schooling until he attended George Washington University (without graduating). Robert's reputation in the field of genetics grew during the 1920s. In 1922 he was appointed editor of the Journal of Heredity and executive officer of the American Genetic Association; in 1932, he became head of the Population Reference Bureau in Washington and maintained that association for thirty more years.

Two men in jackets lok at one another. They are standing outdoors. The man on the right is older.

Although only two Nobel laureates to date have been mother and daughter (physicist Marie Curie won the prize twice and her daughter, Irène Joliot-Curie, received her own award in 1935), the British physicists William Henry Bragg (1862-1942) and William Lawrence Bragg (1890-1971) were only the first of several father-son Nobel recipients. In 1915, the Braggs jointly received the Nobel prize for their work in x-ray crystallography at the University of Cambridge. William Henry Bragg was knighted in 1920 and became Director of the Royal Institution in 1923. William Lawrence Bragg had been a Fellow at Trinity College, Cambridge, when the award-winning research was done and, after several decades at other institutions, he returned to the university in 1938 to become director of the Cavendish Laboratory. William Laurence Bragg was knighted in 1941, and succeeded his father as head of the Royal Institution, serving in that role from 1954 to 1971.

Two men in suits and with mustaches smile and look at one another.