A new variety of the weed Borreria densiflora DC. (Rubiaceae)

Abstract

The weed, known commonly as vassourinha de botão (buttonweed), is present in several crops in northern and north‐eastern Brazil. Its occurrence is common in sugarcane and soybean crops in the states of Goiás, Tocantins, and Maranhão. However, there is no published information in the literature about its taxonomic classification. Thus, this research aimed to classify taxonomically this species in order to develop a classification key based on the morphological characteristics among varieties of Borreria densiflora DC., as well as to illustrate it and provide a palynological basis to classify this species as a new variety. For the classification process, data from the literature, morphological characteristics, and palynological evidence were considered. In this article, we describe a new variety, B. densiflora DC. var. latifolia E.L. Cabral & Martins. The new variety possesses a terrestrial habitat and it is a simple perennial weed species. These results show the importance of an accurate identification, as well as an understanding of the evolutionary changes inherent to weeds (like intraspecific variability), breeding system, genetic potential, and ecological studies. Those factors are essential to the beginning of a long‐term weed management strategy.