Image Interpretation

 

What are the features labeled A-D? Try and identify the plant stems. What can you deduce about the timing of silicification with respect to the taphonomy of the plants in this photograph? The scale bar = 2mm.

A: Well preserved cortex cells in a plant axis
B: Shrunken and partially decayed axes
C: Hemispherical projection
D: Vascular tissue: phloem surrounding a central xylem strand
Plant: Rhynia gwynne-vaughanii
Timing: With regards to taphonomy, the Rhynia axes show two distinct morphologies: some appear very fresh whereas others (e.g. B) appear shrunken. This suggests new stems were growing among older axes that were dying back. The almost complete cellular preservation in the fresh axes suggests the silicification must have occurred at or very soon after the death of the younger shoots