The Givetian flora from Cairo, New York: Rhacophyton, Triloboxylon and Cladoxylon

Petrified Rhacophyton, Triloboxylon and Cladoxylon are described from the Givetian of eastern New York State. In cross section, specimens referable to Rhacophyton ceratangium have a mesarch primary xylem strand in the shape of a bar with swollen endS. Pycnoxylic secondary xylem surrounds the primary xylem. Vascular strands, interpreted as traces, are also present. Triloboxylon has a three-fluted primary xylem strand surrounded by secondary xylem. Several mesarch protoxylem areas are present in cross sectional view. The specimens of Cladoxylon, the first of this genus in the Middle Devonian of North America, show the typical polystelic pattern in cross section. Obvious secondary xylem and peripheral loops are absent. Lateral appendages were observed on two of the specimenS. A comparison of the Cairo and Gilboa floras indicates that they represent different ecological niches during the late Middle Devonian.