Virus Reactions and Taxonomy

Abstract

WE have tried to find some logic in the confusing issues of experimental host ranges of plant viruses^1–4, and this involved an investigation of the group susceptibility of major taxonomic sub-divisions in the Dicotyledons to a number of viruses. Infection data were collected from published sources and grouped according to Hutchinson's classification of flowering plants⁵. In the division Herba-ceae a number of mechanically inoculated viruses consistently infected large proportions of tested species in a few families, notably Solanaceae, and small proportions in others. In general, susceptible families were advanced but not climax families. More primitive families were on the whole less susceptible, unless one of them included the natural field host of the tested virus. The host range data were made more consistent by arranging the tested species according to Hutchinson and by examining them statistically. This suggested that regularities in the data so arranged may provide a test of relationship between plant families. The evidence so far is fragmentary and cannot carry much weight unless it agrees with evidence from other sources, but several examples may be of interest.