Historical review of terminology applied to cambial variants in Nyctaginaceae

Premise of research. The alternative patterns of secondary growth (vascular cambial variants) in stems of Nyctaginaceae are outstanding and has been widely investigated since late 19th century. However, there are controversial interpretations in the literature regarding the existence of one or two types of cambial variants (successive cambia vs. interxylary phloem). Thus, this study aims to explore the morphological diversity of stems in Nyctaginaceae, to unravel the real nature of the cambial variant present in most species of the family.

Methodology. Altogether we analyzed 60 species, focusing on 18 from 12 genera, which were used for the developmental studies. Anatomical and ontogenetic features were characterized from images produced by standardized plant techniques for macro and microscope analyses.

Pivotal results. Our analyses reveal that most species of Nyctaginaceae present stems with polycyclic eustele, which later develop a single cambium that produces secondary xylem a...