or on lateral systems showing limited branching. It seems probable that the xylem, comprising a solid strand of tracheids, was centrarch." However, Edwards and Edwards also decided to include rhyniophytoids, plants which "look like rhyniophytes, but cannot be assigned unequivocally to that group because of inadequate anatomical preservation", but exclude plants like Aglaophyton and Horneophyton which definitely do not possess tracheids.

In 1966, slightly