The son of Robert and Annie Jack, John Jack was born at Châteaugay, Quebec, Canada. His father was a blacksmith-turned-farmer of Scottish descent, his mother a horticulturist of English descent who wrote articles under the title Garden News.
Jack"s education never extended past high school, and he was largely an autodidact with regard botany. In 1886, Jack joined the Arnold Arboretum as a working student under the direction of Professor C. South. Sargent, who recommended Jack"s promotion to Lecturer in arboriculture five years later in 1891. During this period, Jack also spent two summers working as an agent of the Geological Survey, and the Department of Agriculture, exploring the forests of Colorado and of the Bighorn Mountains in Wyoming.
He went on to serve as an Instructor in Forestry at Harvard, and as Lecturer in Forestry at Massachusetts Institute of Technology before appointment as Assistant Professor of Dendrology at the Arnold Arboretum in 1908.
He retired in 1935. Foreign adventures
Jack travelled widely, visiting Europe in 1891, Canada in 1894, and the Far East in 1905, when he returned with seeds of 650 species and varieties of both wild and cultivated plants, many of them new to the United States of America. Notable introductions included the hardy winter hazel Corylopsis glabrescens, and several rhododendrons including schlippenbachii. In 1926, Jack was asked by Sargent to visit Cuba and collect material for the Arnold Arboretum herbarium from the Atkins Institution plantation at Cienfuegos, a task Jack repeated several times over the next nine years until his compulsory retirement when aged 74.
In 1948, Jack fell from a ladder and broke his hip while tending his orchard. Bedridden thereafter, he died the following year aged 88.
A genus and a number of species were named for Jack:
Sinojackia Hu, Alnus jackii, Amelasorbus jackii Rehd., Betula jackii Schneid., Crataegus jackii Sarg., Juniperus communis var.jackii Rehd., Populus jackii Sarg., Quercus jackiana Schneid., Rosa maximowiczii various jackii (Rehd), Viburnum jackii Rehd.
