Fig. 6

Details of petiole-base anatomy of Osmunda pulchella sp. nov. from the Lower Jurassic of Skåne, southern Sweden, revealed via scanning electron microscopy. a Distal cross-section through a petiole. b Detail of (a) showing vascular strand with about eight endarch protoxylem bundles and sclerenchyma mass lining the vascular-strand concavity. c Detail showing helical wall thickening of protoxylem strands (center) compared to multiseriate scalariform wall thickenings of metaxylem tracheids in a petiole vascular bundle (oriented with adaxial side facing upwards). Scale bars: (a) = 1 mm; (b) = 100 μm; (c) = 50 μm