American botanist. Howard Irwin was born in Louisville, Kentucky, but grew up in Long Island, New York. After graduating from the College of Puget Sound in 1950, he spent four years in Guayana, from 1952-1956, as a Fulbright instructor in biology at Queen's College in Georgetown. While there, he made several excursions into the interior of the country and travelled to Brazil to lay the groundwork for his PhD dissertation, a systematic study of Cassia (now Chamaecrista sect. Xerocalyx (Benth.) H.S. Irwin & Barneby). In his spare time, he was a stringer for Time magazine, submitting articles on tropical agriculture and forestry, and assisted photojournalist Alfred Eisenstaedt with the volume on rain forests for the "World We Live In" series.

Throughout his doctoral studies at the University of Texas, Irwin participated in the Venezuelan expeditions mounted by the New York Botanical Garden (NYBG). After receiving his PhD in 1960, he was invited to join the Garden by the head curator, Bassett Maguire, who was organising several simultaneous expeditions to the Guyana Shield. As a research associate, and then as curator, Irwin continued work on Cassia, with the intention of producing a comprehensive monograph of American representatives of the genus, and between 1960 and 1972 participated in eight expeditions to Brazil and the Guyanas. The first, in 1960, was an expedition to the headwaters of the Rio Oiapoque, the boundary between Brazil and French Guiana, with Joăo Murça Pires of Instituto Agronômico do Norte and Water Egler of Museu Goeldi, which resulted in the collection of several thousand numbers from the Tumuchumac range. The following year NYBG sent two expeditions to Amapá: one to Rio Araguarí, led by Pires with NYBG graduate student Gary Irvine, and the other with Irwin and Egler to the Rio Jarí. The Jarí expedition ended disastrously when Egler was killed after his boat lost power and went over a waterfall. Before being allowed to return to the United States, Irwin was detained in jail for nearly three weeks by Brazilian police, who were unconvinced Egler's death was accidental. At the airport, on his way home, he received a telegram with the news that his house had been gutted in a fire. After a year spent resurrecting his house, and working on Cassia at the herbarium, Irwin returned to the field in 1963 to lead a three-month expedition to the Wilhelmina Gebergte in Suriname. In the party were Smithsonian agrostologist Thomas Soderstrom, NYBG graduate student Noel Holmgren, Ghillean Prance, field personnel of the Suriname Forest Department, and several Djuka tribesmen.

Irwin was attracted by the diversity of legumes, especially Chamaecrista and Mimosa, in the Central Brazilian Highlands, or Planalto do Brasil. In 1964, he mounted a long series of expeditions to the region, which continued until 1975 and over the years included scientists from Kew, the Royal Geographical Society, the Smithsonian, Southern Illinois University, University of Michigan, Museu Nacional in Rio, and Universidade de Brasilia, as well as NYBG. As most of the sites on the Planalto expeditions had been little explored previously, the participants on these expeditions contributed to a general, comprehensive collection as well as pursuing their own taxonomic interests. Each collection was made in sets of 10, when possible. Irwin determined the itineraries by reviewing the collection data of early workers, such as Pohl and Glaziou, and matching those sites with recently published road maps. The aim was to recollect important legume material and record habitat information, which was mostly lacking from historical data, as well as to make a more general inventory of the region's flora. In 1972, William Anderson from the University of Michigan replaced Irwin as leader. In all some 225,000 specimens and 35,000 numbers were recorded. The Planalto collections supported numerous monographic and other studies worldwide and were the basis for Irwin and Barneby's American Cassiinae and Barneby's Sensitivae Censitae Mimosa.

In the early 1970s Irwin was instrumental in establishing the Mary Flagler Cary Arboretum in Millbrook, about 75 miles north of NYBG, and afterwards found himself increasingly caught up in the Garden's administration. As a result his research came to a standstill. He was promoted from head curator to executive director in 1972, to vice-president a year later, and shortly afterwards succeeded Bill Steere as president. For the next nine years he administered the NYBG through its most difficult financial period. Near collapse, he resigned in August 1979 and left the Garden the following year. He never returned to his taxonomic research. Instead, after some private consultation projects and a teaching position at Long Island University, he joined the Brooklyn Botanic Garden, where he was involved in the revival of its suburban branch, Clark Botanic Garden, in Nassau County, near his boyhood home.

Sources:
H.S. Irwin, 1996, "Memories of the New York Botanical Garden, 1960-1980", Brittonia, 48(3): 365-371
J. Kallunki, 2007, Ȫn interview with Howard Irwin and William R. Anderson", New York Botanical Garden:
http://sciweb.nybg.org/science2/hcol/planalto/interview.asp.html
NYBG Archives and Manuscripts Collections, 2000, "Howard S. Irwin Records":http://library.nybg.org/finding_guide/archv/irwin_rg4b.html.