Microsporogenesis, microgametogenesis, and pollen morphology of Ambrosia artemisiifolia L. in China

Ambrosia artemisiifolia L. from Ambrosia of the Heliantheae of the Asteraceae family is a recognized harmful weed worldwide and one of the major invasive foreign plants in China. In this study, we investigated its reproductive features, focusing on its microsporogenesis, microgametogenesis, and pollen morphology. The results show that (1) Ambrosia artemisiifolia L. is a dicotyledonous plant and has spherical, tricolpate pollen grains with spiny outer wall; (2) its anther wall comprises four layers, namely epidermis, endothecium, middle layers, and amoeboid tapetum; (3) cytokinesis of microspore mother cells is successive; (4) most of tetrads are tetrahedral; and (5) mature pollen grains are three-celled. In conclusion, although Ambrosia artemisiifolia L. is a dicotyledonous plant with tricolpate pollen, its microsporogenesis is successive, which is different from typical dicots.