Pterocactus valentini

Structure and sites

Segments are light brown, cylindrical and tuberculate. Areoles lack dense woolly hairs. Central spines are cylindrical and about 4–5 mm long in the species comparison. The flower develops at the segment tip. [Las Peñas and Bernardello 2021, Table 2]

The 2021 study included material from Río Negro. The species was classified among southern representatives of Monte. In the chloroplast analysis it belonged to the group also containing P. reticulatus and P. tuberosus. [Las Peñas and Bernardello 2021]

Pollen shape

Gotelli and coauthors described anther and pollen-grain development under the name Pterocactus valentinii (now Pterocactus valentini). Among the four species compared, this plant's pollen was more flattened than the nearly spherical grains of the others, and its outer wall was thicker. [Gotelli et al. 2009] [2-WWW]

The mature grain had numerous pores and small spines on the perforated wall surface. At release it contained a vegetative cell and a generative cell. The authors did not observe division of the latter before release, linking the next stage with pollen tube development. [Gotelli et al. 2009]

Scope of epidermal observations

In the paper comparing Pterocactus epidermis, only one specimen of this species was available for assessment. It lacked papillae and was excluded from the main comparison. The authors considered a link between this trait and developmental stage. A single observation remains narrower than a diagnosis of the whole species. [Faigón et al. 2011]