Evans L. S., Macri A., Stem surface injuries of several species of columnar cacti of Ecuador, Journal of the Torrey Botanical Society, 2008, 135(4):475-482, doi: 10.3159/07-RA-020R1.1
A field comparison of directional changes in stem surfaces in four species from Ecuador. It includes the accumulation of wax layers and a brown covering in grooves between ribs, and an analysis of exposure relative to compass directions. Two Jasminocereus populations on Santa Cruz and San Cristóbal show different degrees of directionality. The paper also presents purposive plant selection criteria and compares the combined result with a model of annual light exposure.