Beginning in late 1934 Allen accompanied
Carroll William Dodge,
Julian Steyermark, and
A. A. Hunter on a 6-month collecting expedition in
Panama. In late 1936, he returned to Panama as the third manager the Missouri Botanical Garden's Tropical Station which had been founded in 1927 by a donation of 7,000 plants from
Charles W. Powell's orchid garden: Powell being the Tropical Station's first manager. When Allen made his trip to Panama as a part of the 1934-35 expedition, A. A. Hunter had taken over as the Tropical Station's second manager and remained in that position as well as Postmaster in Balboa until his death in 1935 at which time Hunter's wife, Mary, took over the Tropical Station's management until a suitable replacement could be found; Allen was selected as that replacement. Allen was the Tropical Stations's third and final manager and filled the position until March 1, 1939, when it was transferred to the Canal Zone Government. "During its almost 13 years of existence, the Tropical Station supplied the greenhouses in Saint Louis with a constant flow of living plants." On March 1, 1939, Allen was jointly hired by the Health Department and the Canal Zone Experiment Gardens. He was to devote five days a week to his work with the Health Department and one day each week, plus such extra time as was required, to outline and supervise the work at the reorganized Balboa Orchid Gardens which was made a branch of the
Canal Zone Experiment Gardens." On September 21, 1939, Allen was transferred from the Health Department to fill the position of Supervisor of Culture, which had been vacant for three years. Allen's work soon expanded to include satisfying the US Army's horticulture requirements for its expansion program in the defense of the Canal. "Between 1937 and 1947, under the auspices of the Missouri Botanical Garden, he was part of 17 expeditions to the forests of Panama and collected over 7,000 species of plants. Allen was 'one of the most meticulous collectors ever to work in Central America.' It would be impossible to name all new species of
Orchidaceae that were discovered by Allen and all of those that were named in his honor." During
World War II, Allen was one of the few American botanists with extensive tropical experience. He joined the
United States Rubber Development Corporation and worked on the collection of rubber from wild
Hevea trees in the
Colombian
Amazon. In 1959 he returned to the United Fruit Company's research department, where he served as the director of the Lancetilla Experimental Station. In 1959 the United Fruit Company launched a major banana breeding project. Allen and
Dutch botanist
J. J. Ochse were selected to lead collecting expeditions to Southeast Asia and the Western Pacific. Between 1959 and 1961 they collected nearly 800 accessions of wild and cultivated species and varieties of bananas from
Taiwan, the
Philippines,
Indonesia,
Malaysia,
Singapore,
Thailand and
Sri Lanka. Thousands of herbarium specimens were submitted by Allen for study and numerous species from different families are named in his honor. Allen's papers are held by the Hunt Institution for Botanical Documentation at
Carnegie Mellon University, together with artwork by his wife, Dorothy. A species of Central American salamander,
Oedipina alleni, is named in honor of Paul H. Allen. ==References==