The N. E. Hansen Papers document the life, career, and plant exploration work of Niels Ebbesen Hansen (1866–1950), a horticulturist, botanist, explorer, and professor at South Dakota State College. Hansen was renowned for developing hardy fruits and forage crops suited for the Great Plains, and this comprehensive collection spans from the late 19th to the mid-20th century, reflecting his pioneering plant-breeding research and global botanical expeditions.

The collection includes correspondence, field notes, manuscripts, publications, journals, plant specimens, photographs, and research files. Early field notebooks and ledgers document Hansen's experimental work in alfalfa, clovers, and grains at the South Dakota Agricultural Experiment Station. Plant introduction records from Russia, Siberia, Turkestan, and China are extensively represented through travel logs, USDA contracts, expense reports, and photographs. Plant specimens and related horticultural data span multiple decades and continents, offering insight into his breeding strategies and selection processes.

Hansen’s manuscripts and publications explore topics such as breeding for cold resistance, disease tolerance, ornamental and edible plant development, and his views on Soviet agricultural practices. Of particular note are his multi-part manuscript series “Russian as Observed by an Agricultural Explorer” (1934–1937), which offers a critical and highly detailed commentary on Soviet collectivization, agrarian policies, and scientific developments. Numerous addresses and lectures document his national and international engagements with scientific and farming communities, including the Dry Farming Congress and State Horticultural Society.

Extensive correspondence from 1873 to the 1940s details his professional relationships with fellow horticulturalists such as Luther Burbank, institutional partners like the USDA, and international contacts including Soviet agronomist N.I. Vavilov. Clippings and biographical files document his recognitions, public reputation as the “Burbank of the Plains,” and memorials in his honor, including his 1949 South Dakota State College tribute and posthumous induction into the South Dakota Hall of Fame.

Photographs in the collection provide vivid documentation of Hansen’s expeditions, including images of him and his assistants in Manchuria, Siberia, and the Da Hinggan Mountains searching for hardy fruits. Other images depict South Dakota State College greenhouses, plant displays, and early experimental plots. Journals from his student years (1879–1883) and professional career reflect his early interests and scientific development.

This collection is a resource for studying early 20th-century plant exploration, American-Soviet agricultural exchange, Great Plains horticulture, and the role of land-grant institutions in shaping regional agricultural adaptation and innovation. Hansen’s impact on food systems, especially through breeding hardy fruits, grasses, and legumes, continues to influence breeding programs worldwide.

Aceraceae Neck. Acer Ginnala Max. Plant specimen from the maple family collected by N.E. Hansen, 1924. N.E. Hansen (1866-1950) was a Danish-American horticulturist and botanist who was a pioneer in plant breeding. Hansen came to South Dakota in 1895 and became the first head of the Horticultural Department of South Dakota State College. He also served as agricultural explorer for the United States Department of Agriculture. He searched for hardy grasses, fruits, and other plants throughout Europe and Asia and brought them back to the United States to raise or crossbreed with American varieties to produce hardy plants. Specimen is mounted on an 11.5 x 16.5 inch herbarium sheet accompanied by a label printed in Russian in Cyrillic letter with hand-written notation in black ink.

Aceraceae Neck. Acer Mairunduense ? et Mey.. Plant specimen from the maple family collected by N.E. Hansen, 1924. N.E. Hansen (1866-1950) was a Danish-American horticulturist and botanist who was a pioneer in plant breeding. Hansen came to South Dakota in 1895 and became the first head of the Horticultural Department of South Dakota State College. He also served as agricultural explorer for the United States Department of Agriculture. He searched for hardy grasses, fruits, and other plants throughout Europe and Asia and brought them back to the United States to raise or crossbreed with American varieties to produce hardy plants. Specimen is mounted on an 11.5 x 16.5 inch herbarium sheet accompanied by a label printed in Russian in Cyrillic letter with hand-written notation in black ink.

Aceraceae Neck. Acer Mons Max. Plant specimen from the maple family collected by N.E. Hansen, 1924. N.E. Hansen (1866-1950) was a Danish-American horticulturist and botanist who was a pioneer in plant breeding. Hansen came to South Dakota in 1895 and became the first head of the Horticultural Department of South Dakota State College. He also served as agricultural explorer for the United States Department of Agriculture. He searched for hardy grasses, fruits, and other plants throughout Europe and Asia and brought them back to the United States to raise or crossbreed with American varieties to produce hardy plants. Specimen is mounted on an 11.5 x 16.5 inch herbarium sheet accompanied by a label printed in Russian in Cyrillic letter with hand-written notation in black ink.

Aceraceae Neck. Acer Tomentosum Max. Plant specimen from the maple family collected by N.E. Hansen, 1924. N.E. Hansen (1866-1950) was a Danish-American horticulturist and botanist who was a pioneer in plant breeding. Hansen came to South Dakota in 1895 and became the first head of the Horticultural Department of South Dakota State College. He also served as agricultural explorer for the United States Department of Agriculture. He searched for hardy grasses, fruits, and other plants throughout Europe and Asia and brought them back to the United States to raise or crossbreed with American varieties to produce hardy plants. Specimen is mounted on an 11.5 x 16.5 inch herbarium sheet accompanied by a label printed in Russian in Cyrillic letter with hand-written notation in black ink.

Caprifoliaceae Vent. Lonicera edulis Turcr. Plant specimen from the honeysuckle family collected by N.E. Hansen, 1924. N.E. Hansen (1866-1950) was a Danish-American horticulturist and botanist who was a pioneer in plant breeding. Hansen came to South Dakota in 1895 and became the first head of the Horticultural Department of South Dakota State College. He also served as agricultural explorer for the United States Department of Agriculture. He searched for hardy grasses, fruits, and other plants throughout Europe and Asia and brought them back to the United States to raise or crossbreed with American varieties to produce hardy plants. Specimen is mounted on an 11.5 x 16.5 inch herbarium sheet accompanied by a label printed in Russian in Cyrillic letter with hand-written notation in black ink.

Caprifoliaceae Vent. Lonicera Maacki Turcr. Plant specimen from the honeysuckle family collected by N.E. Hansen, 1924. This plant is native to temperate western Asia, specifically in northern and western China south to Yunnan, Mongolia, Primorsky Krai in southeastern Russia, Korea, and, albeit rare there, central and northern Honshu, Japan. N.E. Hansen (1866-1950) was a Danish-American horticulturist and botanist who was a pioneer in plant breeding. Hansen came to South Dakota in 1895 and became the first head of the Horticultural Department of South Dakota State College. He also served as agricultural explorer for the United States Department of Agriculture. He searched for hardy grasses, fruits, and other plants throughout Europe and Asia and brought them back to the United States to raise or crossbreed with American varieties to produce hardy plants.

Pinus pungens, also called Table Mountain Pine, hickory pine, prickly pine or mountain pine. This small pine is native to the Appalachian Mountains in the United States. Plant specimen collected by C.S. Sargent, 1912, first director of the Arnold Arboretum, Herbarium of Iowa College of Agriculture and Mechanic Arts, Ames, Iowa. N.E. Hansen graduated from Iowa State College with a bachelor's degree in horticulture in 1887. It is likely Hansen obtained this specimen during his time at the college. N.E. Hansen (1866-1950) was a Danish-American horticulturist and botanist who was a pioneer in plant breeding. Hansen came to South Dakota in 1895 and became the first head of the Horticultural Department of South Dakota State College. He also served as agricultural explorer for the United States Department of Agriculture. He searched for hardy grasses, fruits, and other plants throughout Europe and Asia and brought them back to the United States to raise or crossbreed with American varieties to produce hardy plants. Specimen is mounted on an 11.5 x 16.5 inch herbarium sheet accompanied by a label with hand-written notation in pencil ink.

Primulaceae Vent. Primula. Plant specimen collected by N.E. Hansen, 1924. N.E. Hansen (1866-1950) was a Danish-American horticulturist and botanist who was a pioneer in plant breeding. Hansen came to South Dakota in 1895 and became the first head of the Horticultural Department of South Dakota State College. He also served as agricultural explorer for the United States Department of Agriculture. He searched for hardy grasses, fruits, and other plants throughout Europe and Asia and brought them back to the United States to raise or crossbreed with American varieties to produce hardy plants.

Prunus persica. Dbl. fl. Peach. Kaises VII. Plant specimen collected by N.E. Hansen, 1924. The peach (Prunus persica) is a deciduous tree native to the region of Northwest China between the Tarim Basin and the north slopes of the Kunlun Shan mountains, where it was first domesticated and cultivated. N.E. Hansen (1866-1950) was a Danish-American horticulturist and botanist who was a pioneer in plant breeding. Hansen came to South Dakota in 1895 and became the first head of the Horticultural Department of South Dakota State College. He also served as agricultural explorer for the United States Department of Agriculture. He searched for hardy grasses, fruits, and other plants throughout Europe and Asia and brought them back to the United States to raise or crossbreed with American varieties to produce hardy plants. Specimen is mounted on an 11.5 x 16.5 inch herbarium sheet accompanied by a label with hand-written notation in pencil ink.

Rosaceae B. Juss. Micromeles alnifolia Koehne. Plant specimen collected by N.E. Hansen, 1924. N.E. Hansen (1866-1950) was a Danish-American horticulturist and botanist who was a pioneer in plant breeding. Hansen came to South Dakota in 1895 and became the first head of the Horticultural Department of South Dakota State College. He also served as agricultural explorer for the United States Department of Agriculture. He searched for hardy grasses, fruits, and other plants throughout Europe and Asia and brought them back to the United States to raise or crossbreed with American varieties to produce hardy plants. Specimen is mounted on an 11.5 x 16.5 inch herbarium sheet accompanied by a label printed in Russian in Cyrillic letter with hand-written notation in blank ink.

Rosaceae B. Juss. Prunus padus L. Plant specimen collected by N.E. Hansen, 1924, also known as bird cherry, hackberry, hagberry, or Mayday tree, is a species of cherry, native to norther Europe and northern Asia. N.E. Hansen (1866-1950) was a Danish-American horticulturist and botanist who was a pioneer in plant breeding. Hansen came to South Dakota in 1895 and became the first head of the Horticultural Department of South Dakota State College. He also served as agricultural explorer for the United States Department of Agriculture. He searched for hardy grasses, fruits, and other plants throughout Europe and Asia and brought them back to the United States to raise or crossbreed with American varieties to produce hardy plants. Specimen is mounted on an 11.5 x 16.5 inch herbarium sheet accompanied by a label with hand-written notation in pencil ink.

Rosaceae B. Juss. Pyrus ussuriensis Max +P. Sinensis Lindl. Plant specimen collected by N.E. Hansen, 1924, also known as the Ussurian pear, Harbin pear, and Manchurian pear, is a species of flowering plant in the family Rosaceae. It is native to Korea, Japan, and the Ussuri River area of far eastern Russia. N.E. Hansen (1866-1950) was a Danish-American horticulturist and botanist who was a pioneer in plant breeding. Hansen came to South Dakota in 1895 and became the first head of the Horticultural Department of South Dakota State College. He also served as agricultural explorer for the United States Department of Agriculture. He searched for hardy grasses, fruits, and other plants throughout Europe and Asia and brought them back to the United States to raise or crossbreed with American varieties to produce hardy plants. Specimen is mounted on an 11.5 x 16.5 inch herbarium sheet accompanied by a label printed in Russian in Cyrillic letter with hand-written notation in blank ink.

Rosaceae B. Juss. Spirea Chamaedrifolia L. Common name germander meadowsweet or elm-leaved spirea. Plant specimen collected by N.E. Hansen, 1924. Spiraea chamaedryfolia is a shrub reaching a height of 1–1.5 meters (3 feet 3 inches–4 feet 11 inches). Branchlets are brownish or red-brown. Leaves are simple, oblong or lance-shaped, toothed on the edges, 40–60 millimeters (1.6–2.4 inches) long and 10–30 millimeters (0.39–1.18 inches) wide, with a petiole of 4–7 millimeters. The white flowers of 6–9 millimeters in diameter grow in spike-like clusters at the ends of the branches. Flowering period extends from May to September. N.E. Hansen (1866-1950) was a Danish-American horticulturist and botanist who was a pioneer in plant breeding. Hansen came to South Dakota in 1895 and became the first head of the Horticultural Department of South Dakota State College. He also served as agricultural explorer for the United States Department of Agriculture. He searched for hardy grasses, fruits, and other plants throughout Europe and Asia and brought them back to the United States to raise or crossbreed with American varieties to produce hardy plants. Specimen is mounted on an 11.5 x 16.5 inch herbarium sheet accompanied by a label printed in Russian in Cyrillic letter with hand-written notation in black ink.

Rosaceae B. Juss. Spirea Chamaedrifolia L. Common name germander meadowsweet or elm-leaved spirea. Plant specimen collected by N.E. Hansen, 1924. Spiraea chamaedryfolia is a shrub reaching a height of 1–1.5 meters (3 feet 3 inches–4 feet 11 inches). Branchlets are brownish or red-brown. Leaves are simple, oblong or lance-shaped, toothed on the edges, 40–60 millimeters (1.6-2.4 inches) long and 10-30 millimeters (0.39-1.18 inches) wide, with a petiole of 4-7 millimeters. The white flowers of 6-9 millimeters in diameter grow in spike-like clusters at the ends of the branches. Flowering period extends from May to September. N.E. Hansen (1866-1950) was a Danish-American horticulturist and botanist who was a pioneer in plant breeding. Hansen came to South Dakota in 1895 and became the first head of the Horticultural Department of South Dakota State College. He also served as agricultural explorer for the United States Department of Agriculture. He searched for hardy grasses, fruits, and other plants throughout Europe and Asia and brought them back to the United States to raise or crossbreed with American varieties to produce hardy plants. Specimen is mounted on an 11.5 x 16.5 inch herbarium sheet accompanied by a label printed in Russian in Cyrillic letter with hand-written notation in black ink.

Rosaceae B. Juss. Spirea media Schmidt. Plant specimen collected by N.E. Hansen, 1924. N.E. Hansen (1866-1950) was a Danish-American horticulturist and botanist who was a pioneer in plant breeding. Hansen came to South Dakota in 1895 and became the first head of the Horticultural Department of South Dakota State College. He also served as agricultural explorer for the United States Department of Agriculture. He searched for hardy grasses, fruits, and other plants throughout Europe and Asia and brought them back to the United States to raise or crossbreed with American varieties to produce hardy plants. Specimen is mounted on an 11.5 x 16.5 inch herbarium sheet accompanied by a label printed in Russian in Cyrillic letter with hand-written notation in blank ink.

Saxifragaceae Dumort. Deutzia parviflora Bunge. Plant specimen collected by N.E. Hansen, 1924. Saxifragaceae are found mostly in the Northern Hemisphere, with centers of diversity in the Himalayas, East Asia, and Western North America. N.E. Hansen (1866-1950) was a Danish-American horticulturist and botanist who was a pioneer in plant breeding. Hansen came to South Dakota in 1895 and became the first head of the Horticultural Department of South Dakota State College. He also served as agricultural explorer for the United States Department of Agriculture. He searched for hardy grasses, fruits, and other plants throughout Europe and Asia and brought them back to the United States to raise or crossbreed with American varieties to produce hardy plants. Specimen is mounted on an 11.5 x 16.5 inch herbarium sheet accompanied by a label printed in Russian in Cyrillic letter with hand-written notation in blank ink.

Saxofragaceae Dumort. Ribes manshuricum (Max.) Kom. Plant specimen collected by N.E. Hansen, 1924. Saxifragaceae are found mostly in the Northern Hemisphere, with centers of diversity in the Himalayas, East Asia, and Western North America. N.E. Hansen (1866-1950) was a Danish-American horticulturist and botanist who was a pioneer in plant breeding. Hansen came to South Dakota in 1895 and became the first head of the Horticultural Department of South Dakota State College. He also served as agricultural explorer for the United States Department of Agriculture. He searched for hardy grasses, fruits, and other plants throughout Europe and Asia and brought them back to the United States to raise or crossbreed with American varieties to produce hardy plants. Specimen is mounted on an 11.5 x 16.5 inch herbarium sheet accompanied by a label printed in Russian in Cyrillic letter with hand-written notation in black ink.