Figure 9. Compressions and impressions of Equisetum stems, Salvinia leaflets and megaspores, and Cyclosorus pinnate leaves from Late Oligocene volcaniclastic strata in the Margargaria River localities, northwestern Ethiopian Plateau. 9.1 Cross section of an in situ Equisetum stem with a characteristic hollow central part and ribbed margin pattern. CH-79-35A. Scale bar equals 0.1 cm. 9.2 Equisetum stem fragment with enlarged node covered by a sheath of material that represents a whorl of leaves. White oblique bar indicates whorl of leaves. CH-93-85. Scale bar equals 0.5 cm. 9.3 Dispersed ovate-obovate Salvinia leaflets. CH-93-62B. Scale bar equals 0.25 cm. 9.4 Folded Salvinia leaflet pair bearing remains of a submerged leaf (reddish-brown filaments) attached to the distal end. CH-93-48A. Scale bar equals 0.25 cm. 9.5 Ellipsoidal Salvinia megaspore. Oblique white bars in the picture indicate 2-lobed acrollamella. Note coarsely rugulate surface ornamentation. CH-79-21A. Scale bar equals 100 µm. 9.6 Fragment of Salvinia leaflet showing thick midvein and proximally-curved anastomosed secondary veins forming irregular to polygonal areoles. CH-93-69B. Scale bar equals 0.1 cm. 9.7 Detail of Salvinia leaflet venation showing large areoles subdivided into smaller polygonal areoles and marginal vein connecting terminal secondary veins. CH-93-81. Scale bar equals 0.1 cm. 9.8 General view of Cyclosorus pinnate leaf fragment showing circinate venation. CH-79-43B. Scale bar equals 0.5 cm. 9.9 Cyclosorus pinnate leaf fragment showing alternate secondary pinnae arrangement. Note gradually reduced pinnate leaf fragment on bottom left side of image. CH-79-43B. Scale bar equals 0.5 cm. 9.10 Possible fertile Cyclosorus pinnate leaf fragment. Oblique black bars point to possible clusters of sporangia consisting of approximately circular organic remains on pinnules secondary veins. CH-87-1A. Scale bar equals 0.1 cm.