Terrazas T., Escamilla-Molina R., Vázquez-Sánchez M., Variation in the tracheary elements in species of Coryphantha (Cacteae-Cactoideae) with contrasting morphology: the bottleneck model, Brazilian Journal of Botany, 2016, 39(2):669-678, doi: 10.1007/s40415-016-0249-z
A study of conducting elements in the stem axis and tubercles of six Coryphantha groups with different morphologies. It compares vessels, wide-band tracheids and cortical bundles. It considers vessel narrowing in tubercles as a model of restricted water transport and discusses wood heterogeneity.