Image Interpretation

 

What are the features labeled A-D? Try and identify the plant stems. What problems are there in identifying these plants? The scale bar = 5mm.

A: Geopetal sediment in a plant straw
B: A xylem strand displaced during the decay and shrinkage of the plant stem
C: A cemented fracture cutting previously silicified plant axes and matrix
D: Shrunken and partially decayed axes
Plant: Straws of Aglaophyton major.
Problems: Many anatomical features have been lost prior to silicification due to the shrinkage and partial to almost complete decay of the plants. A few clues remain to identify them at the magnification in this photograph; partly the relatively large diameter of the axes but more specifically the pattern of cortex decay (bottom left) is primarily found in Aglaophyton. We cannot tell at this magnification if the xylem cells lack thickenings.