The trimerophytes are probably a basal group leading to the emergence of other plant groups. They lacked leaves and roots. The plant body was composed of photosynthetic branching stems. There was a protostele in the center of the stem and therefore these had vascular tissue. Enations are found on some trimerophytes.
Enations are small flaps of tissue without vascularization.
They are leaf-like, but because they lack vascular tissue, they are not true leaves. The enations give the plants a thorny appearance. The sporagnia are borne ath the tips of the branches like the rhyniophytes. The sporangia are spindle shaped and homosporous. Trimerophytes varied in size from a few inches to three feet in height.