and the rhizomes were from Taeniocrada.

In 1871, Dawson described specimens which had strong spines as P. princeps var. ornatum. He considered that groups of paired terminal sporangia found with these were part of the same plant, although no actual connection was found. Much later, in 1967, it was shown that fossils called "Psilophyton princeps" had two very different patterns of xylem development: from the centre outwards (centrarch) in P. princeps and from