FERRUCCI Maria silvia
Embryological studies of Magonia pubescens (Dodonaeaeae, Sapindaceae): development of male and female gametophytes in both floral morphs and its phylogenetic implications.
GONZÁLEZ V.V.; SOLÍS S. M.; FERRUCCI M.S.
AUSTRALIAN SYSTEMATIC BOTANY
Lugar: Collingwood; Año: 2017 vol. 30 p. 279 - 289
Magonia pubescens A.St.-Hil. (Dodonaeaeae,Sapindaceae) is a monoecious species exhibiting two floral morphs, namelystaminate flowers, with gynoecium reduced to a pistillode, and morphologicallyhermaphrodite but functionally pistillate flowers. It presents the basic typeof antheral wall development. Microsporogenesis is normal, forming tetrahedraland decussate tetrads. Anatomical differences in anthers between floral morphsbecome visible at the stage of callose wall degradation and release of tetrads.In staminate flowers, the endothecium develops fibrous thickening, and the twomiddle layers, the tapetum and the parenchymal septum that separates bothlocule, are degraded. At dehiscence, permanent calymmate tetrads are released.Magonia is the only genus of the family with this type of pollen unit. Inpistillate flowers, the endothecium exhibits fibrous thickening only in threeto five cells on the dorsal loculus, and only the inner middle layer collapses.The septum that separates both locules remains unaltered, the stomium isnon-functional, mature anthers are indehiscent and show collapsed tetrads. Instaminate flowers, the gynoecium is reduced to a tricarpellar pistillode, trilocular,with ovules that degenerate after megasporogenesis. In pistillate flowers, thegynoecium has a tricarpellary ovary, with six to eight ovules per carpel; theyare campylotropous, bitegmic, mixed crassinucellate, and exhibit a well-developedobturator. The phylogenetic implications of these embryological characters arediscussed in the context of the family.