Fig. 5From: Osmunda pulchella sp. nov. from the Jurassic of Sweden—reconciling molecular and fossil evidence in the phylogeny of modern royal ferns (Osmundaceae)Basal to distal sections of petiole bases of Osmunda pulchella sp. nov. from the Lower Jurassic of Skåne, southern Sweden (NRM-S069657), showing successive stages of petiole-base differentiation. a Parenchymatous inner cortex and petiolar wings. b–e Development of an abaxial arch of thick-walled fibres in the sclerenchyma ring. c Appearance of a sclerenchyma patch in the bundle concavity. d Appearance of a sclerenchyma mass in the petiolar wing. f Sclerenchyma ring with two prominent lateral masses of particularly thick-walled fibres. g Collapsed outermost petiole (note rock matrix above) showing sclerenchyma ring with one abaxial and two lateral masses of particularly thick-walled fibres, and elongate sclerenchyma strips (e.g. bottom, right) isolated from degraded stipular wings of adjacent petioles. Scale bars = 500 μmBack to article page