Ninety six varieties of Ricinus communis, L. were studied as for their growth habit, height, length and number of internodes from the base of the plant to its first inflorescence, types of branching, color of branches and various characters of leaves, inflorescences, fruit clusters, fruits and seeds ; earliness ; yielding capacity and porcentage of oil in the seeds. The description of several of the quantitative characters is supplemented by numerical data, which are also presented graphically. The extreme variability of Ricinus offers excellent opportunities not only for genetical studies but also for breeding new and better varieties for cultivation.

In the introduction to this article data are presented to show the growing economic importance of the cultivation of Ricinus in Brasil and particularly in the State of São Paulo. Following general statements regarding the botany, the origin and the geographic distribution of this genus, the investigations are outlined which are carried out by the Divisions of Genetics and Oil Plants of the Instituto Agronômico of the State of São Paulo, Brasil, to improve this important crop plant. Summarising, these investigations deal with the following subjects : a) Organisation of a large collection of types ; b) Investigations concerning the variability of the genus Ricinus c) Genetic analysis; d) Regional variety trials ; e) Improvement of the best varieties by individual selection and progeny trials ; f) Regional strain tests ; g) Breeding of improved varieties through hybridisation. In spite of the fact that these investigations have only been carried out for a few years, they are already furnishing results of economic importance, as seeds of superior varieties are already on sale to the farmers.