Author:

Keywords:

Ranunculiflorae, Androecium, merosity, reduction, secondary increase, nectar-leaves, petals, Science & Technology, Life Sciences & Biomedicine, Plant Sciences, Evolutionary Biology, 0603 Evolutionary Biology, 0607 Plant Biology, 3104 Evolutionary biology, 3108 Plant biology

Abstract:

Four different evolutionary lines can be recognised for the androecium of the Ranunculiflorae: (1) a progressive reduction in the number of stamens and stamen whorls. (2) The transformation of the outermost stamens into nectar-leaves or petals. (3) Meristic changes of the flower. (4) Secondary increases in the number of stamens. It is shown that the position and inception of the stamens is valuable to understand relationships of taxa. Ranunculaceae occupy a basal position with the greatest androecial diversity and a reductive trend, linked with a shift from trimery to pentamery and the transformation of the outer stamen pairs into (nectariferous) petals. Berberidaceae and satellite families have androecia with an alternation of trimerous (dimerous) whorls and outer staminodial nectar-leaves. In Papaverales the trimerous flower with a polycyclic androecium often becomes dimerous and is progressively reduced. Secondary increases occur occasionally in Berberidaceae, Papaveraceae and perhaps Glaucidiaceae.