Edgar Shannon Anderson (1897 – 1969) was an American botanist and plant geneticist, a Professor of Botany at Washington University, a Director of Missouri Botanical Garden, and Lecturer in Botany at Harvard and Columbia Universities.
Tradescantia Andersoniana Group is named after Anderson who studied the species and discovered the parentage of many of the hybrids found in the United States and Europe.
Following his ten year long scientific study, Anderson published A Cytological Monograph of the American Species of Tradescantia in the Botanical Gazette in March 1936 which is probably the most intensive and detailed study of the species to date.
Subsequently, as well as Iris, Anderson also studied Tradescantia virginiana as part of his work on his 1949 paper titled Introgressive hybridization, “the spread of genes of one species into the gene complex of another as a result of hybridization between numerically dissimilar populations in which extensive backcrossing prevents formation of a single stable population”. Put more simply, different species of Tradescantia in the wild crossed and repeatedly back crossed with their parents which created a range of interspecific hybrids. Anderson isolated the three main species responsible as Tradescantia virginiana, Tradescantia ohiensis (formerly reflexa) and Tradescantia subaspera (formerly pilosa) which all have overlapping ranges across the mid-west of the United States.
Initially, these interspecific hybrids became erroneously known as Tradescantia × andersoniana but were later properly assembled into a plant group which was officially named Tradescantia Andersoniana Group. This Group has grown as new plants have been discovered, named, and added over the years, and now includes cultivars specifically bred to produce differing leaf and flower colours, plant heights and form. It is estimated that the Andersoniana Group could now number more than 75 cultivars excluding synonyms. A lot of further work needs to be done to locate, verify and record these cultivars, particularly in North America.
I have been lucky enough to obtain a copy of Anderson’s book published in 1952 titled Plants, Man & Life, in which he describes the scientific study on Tradescantia virginiana and other closely related species carried out over a ten year period with his colleague Dr Karl Sax, and his former student, Dr, R.E Woodson, resulting in their authoritative monograph published in 1936. The book provides a fascinating insight into their botanical field research, desk research and conclusions, but written in a very readable and non-technical style. As my Collection develops, I will be quoting extensively from the book to support a lot of facts and theories about Tradescantia which have hitherto gone unnoticed or unexplained.