Silva S. C. D. M., Machado S. R., Nepi M., Rodrigues T. M., Structure and function of secretory glochids and nectar composition in two Opuntioideae (Cactaceae) species, Botany, 2020, 98(8):425-437, doi: 10.1139/cjb-2020-0004
The paper compares glochids of four Brasiliopuntia brasiliensis and five Opuntia cochenillifera plants (Nopalea cochenillifera in the publication). Microscopy, histochemistry and HPLC describe secretory function and xylem and phloem at the glochid bases.