The Virtual Petrified Wood Museum.  Dedicated to the Exhibition and Educational Study of Permineralized Plant Material
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Arthropitys Xylem (Calamites stem)
Carinal Canals of Arthropitys or Calamites
A close-up of the central pith of the petrified calamitean stem Arthropitys reveals tubular structures called carinal canals, which are surrounded by primary xylem. The photo was taken at 40x. These structures measure 300 micrometers in diameter. Secondary xylem can be seen radiating away from the carinal canals. Individual tracheids in this area measure 20 to 50 micrometers in diameter. Medullary rays can be seen between the carinal canals and secondary xylem.

With this close-up we can make sense of the exterior ribs found on Calamites pith casts. The ribs correspond to the rays. The depressed areas between the ribs are where the carinal canals extended into the pith cavity. You can visit the Brazil Gallery in the Permian section of our museum to see a sequence of photos that zoom in on the photo above.
Calamites Steinkern
Calamites Pith Cast
West Virginia
16 cm long x 6.5 cm diameter

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