São apresentados os resultados de quatro expedições, realizadas entre 1962 e 19652, nas quais foram levantadas as formas perenes de algodoeiro existentes em regiões da bacia do rio São Francisco, dos estados nordestinos, do litoral paulista e adjacências, de Mato Grosso, sul de Goiás e Triângulo Mineiro. À maneira de S. G. Stephens, as formas em aprêço são discriminadas, conforme seu modo de ocorrência, em seis categorias: A) selvagem ou asselvajadas; B) semi-asselvajadas; C) domésticas; D) de subsistência; E) cultivares primitivos; F) tipos nativos melhorados. Consideradas em função do desenvolvimento econômico-social, essas categorias articulam-se formando um sistema que se adequa ao estudo da evolução do algodoeiro como planta cultivada. Rim-de-boi (G. barbadense r. brasiliense Hutch), Quebradinho (G. barbadense L.) e Mocó, ecótipo de G. hirsutum r. marie-galante Hutch., os três tipos principais de algodoeiros nativos, são encontrados nas formas B, C, D e E. Apenas o Mocó apresenta-se, também, como linhagens melhoradas (F) e tem real expressão na economia nacional. Vários outros tipos perenes de G. hirsutum e de G. barbadense, êstes últimos distintos dos tipos nativos, ocorrem como formas domésticas (C) e semi-asselvajadas (B). A única forma selvagem ou asselvajada (A) descoberta - "caicoense" - não parece relacionar-se, pelo menos diretamente, com nenhum dos tipos anteriores. Várias hipóteses são aventadas, principalmente sobre origem, evolução e migração dos três tipos mais difundidos, ampliando as perspectivas das investigações. É apresentado um mapa mostrando a distribuição geográfica dos vários tipos e as regiões de maior interesse a serem exploradas no prosseguimento das investigações.

Four expeditions, covering regions of Brazil, located between 5.° and 25.° south, latitude, were performed by the authors, during the period from 1962 to 1965. They were supported by the Fundação de Amparo à Pesquisa do Estado de São Paulo and their aims were: (a) to determine the present geographical distribution of perennial forms of cotton plants; (b) to get samples of these forms to keep them in herbaria and in living collections, at the Instituto Agronômico, Campinas, for further studies. The working program was based on the S. G. Stephens, discrimination of perennial forms of cotton plants according to the mode of their occurrence, namely: wild, semi-feral, commensal, subsistence, primitive cultigen and improved native type. Several regions of the following states were explored in the expeditions: (1st) regions of the São Francisco river basin of the states Minas Gerais, Bahia and Pernambuco; (2nd) the northeastern region, comprising Alagoas, Pernambuco, Paraíba, Rio Grande do Norte and Ceará; (3rd) coastal regions of the state of São Paulo; (4th) regions of the state of Mato Grosso, southern part of Goiás and a region of the state of Minas Gerais, known as "Triângulo Mineiro". Three native types were recognized as being the most largely dispersed: (1) the "kidney" cotton (Gossypium barbadense r. brasiliense Hutch.) found in most of the studied regions. Its center of origin seems to be the northern part of the state of Mato Grosso; the "Quebradinho" (G. barbandese L.) which is found from the inner regions of the states Goiás, Minas Gerais and Bahia as far as the coastal mountains of São Paulo. Although it is admitted that this type has spread south from the state Maranhão, in the 19th century, its center of origin is not known yet; (3) the "Moco", an ecotype of G. hirsutum r. marie galante Hutch., is present in all semi-arid regions of northeastern Brazil. Of these three types, the latter is the only really important one as economic crop and presenting improved strains. Many evidences indicate the Seridó valley as its center of origin. The three cotton types were found as semi-feral, commensal, subsistence, and primitive cultigen forms. A wild cotton was traced near Caicó, Rio Grande do Norte, and named "caicoense", but it does not seem that it is related with any of the above referred types. Several perennial types of G. hirsutum, distinct from "Mocó", were collected as commensal and semi-feral forms in several regions of the northeast. Some types of G. barbadense, different from the native ones, were acknowledged in coastal regions of Alagoas, Bahia, Rio de Janeiro and São Paulo, and also near the border of Paraguay. They probably are remnants of ancient introductions. The results of the expeditions are shown on a map, pointing out the geographical distribution of the cotton types located.