De la Rosa-Tilapa A., Vázquez-Sánchez M., Terrazas T., Stem anatomy of Turbinicarpus s.l. (Cacteae, Cactaceae) and its contribution to systematics, Plant Biosystems, 2019, 153(4):600-609, doi: 10.1080/11263504.2018.1527791
A comparison of stem anatomy in 35 taxa historically assigned to Turbinicarpus. It describes the epidermis, stomata, hypodermis, parenchymatous tissues, vascular bundles, xylem, phloem and periderm. The distribution of crystals and fibres in cortical bundles supports recognition of three evolutionary lineages. It also shows species-level exceptions, including bundle structure in T. alonsoi, T. lophophoroides and the current Rapicactus subterraneus.