The Auriculate Pollen Grain of Hymenocallis Quitoensis Herb. (Amaryllidaceae) and Its Systematic Implications

The pollen grain of Hymenocallis quitoensis Herb, is examined with scanning and transmission electron microscopy. The very large, monosulcate grain is characterized by a coarsely reticulate exine surface and solid, auriculate appendages at the equatorial facies. Surface morphology of the pollen grain of H. quitoensis is compared with other representative species of Hymenocallis and supports the inclusion of H. quitoensis within the genus. Meridional exine dimorphism in other species of Hymenocallis is interpreted as a reduction from the well‐defined auriculae of H. quitoensis. Surface morphology of the pollen grain of Hymenocallis sects. Artema Traub and Elisena (Herb.) Traub exhibits divergence from that of sects. Hymenocallis and Ismene (Herb.) Traub. Phylogenetic and paleobotanical implications of the auriculate pollen grain are briefly discussed.