F.  Vergara-Silva, Espinosa-Matías, S., Ambrose, B. A., Vázquez-Santana, S., Martínez-Mena, A., Márquez-Guzmán, J., Martínez, E., Meyerowitz, E. M., and Alvarez-Buylla, E. R., ?Inside-out flowers characteristic of Lacandonia schismatica  evolved at least before its divergence from a closely related taxon, Triuris brevistylis?, Int. J. Plant Sci., vol. 164, pp. 345 - 357, 2003.