These can be separated by the presence of a small flap of tissue, the ligule, within a modified area on the adaxial surface of the leaf. Vascular tissue has been identified in the sporangial area. These plants possess kidney-shaped sporangia and may have attained heights of several meters. Colpodexylon is a larger plant, with axes attaining 2.5 cm in diameter and a length of 60 cm. Leaves are helically arranged and three-forked.
Sporophylls bear an adaxial, elliptical sporangium.
Stomates are found both on the leaves and stems. Fertile leaves bear an adaxial sporangium, and these are intermixed with sterile leaves along the upright axes. Most of the Early Devonian plants are small in stature, and vegetation was not stratified initially. Tiering of these plant communities began with the appearance of pseudomonopodial and monopodial growth habits, the result of a change in growth and development of the growing meristem. These early plant clades existed into the Middle Devonian where newly evolved plants were larger in size and more complex in architecture.