Sánchez D., Terrazas T., Grego-Valencia D., Arias S., Phylogeny in Echinocereus (Cactaceae) based on combined morphological and molecular evidence: taxonomic implications, Systematics and Biodiversity, 2018, 16(1):28-44, doi: 10.1080/14772000.2017.1343260
The phylogenetic analysis combines 44 morphological characters and six chloroplast DNA regions. It includes 59 Echinocereus species and ten comparative taxa. Eight main lineages were recovered and a corresponding sectional classification was proposed, with discussion of data congruence and the problematic placement of E. poselgeri.