Anatomical confirmation of root parasitism in Brazilian Agalinis Raf. species (Scrophulariaceae)

摘要

Agalinis Raf. consists approximately of 60 species, 14 of which occur in Brazil. The genus presents predominantly american distribution and the Brazilian species appears mainly in high areas of Minas Gerais. The North-American species are refered as hemiparasites, but there is no anatomical data about it in relation to the Brazilian species. Anatomical studies were conducted to verify whether the Agalinis species from Brazil were root parasites or not. The eight species analysed were presented haustoria which varied in shape, arrangement and size. They were generally elliptic or globose structures and mostly were tightly sticked to other roots in a solitary or clustered manner. The seriate sections of haustoria showed that there was a xylem connection between them and the roots in which they were attached. This fact has confirmed for the first time the occurrence of parasitism in the Brazilian species of Agalinis.