Australian Horsetail Phyllotheca Leaf Whorl

Description: This fine specimen is a member of the Calamitales which belong to the Sphenophytes. Whorls of small leaflets are arranged concentrically around a thin stem and are called Annularia or Asterophyllites. Calamites itself is the name originally given to a stem section, but now applies to the entire plant. These were indicative of humid to wet habitats such as along rivers and lake shores. The Horsetails are also termed Arthrophytes, or jointed plants, due to their construction of regular segments. The only living example of the sphenophytes is the horsetail Equisetum. This specimen shows a leaf whorl which has become detached from the stem showing the star like appearance for which such whorls are named.