The earliest known tracheophytes belonged to the extinct phylum
Cooksonia and related genera Rhynia, Aglaophyton from mid Silurian to Early Devonian represent earliest unequivocal vascular plants assigned to extinct phylum Rhyniophyta, now considered basal polysporangiophytes or protracheophytes. They possessed dichotomously branching naked axes with terminal sporangia and simple S-type annular tracheids, but lacked true roots and leaves. Bryophyta are nonvascular, while Lycophyta and Monilophyta diversified later from zosterophyll ancestors. Rhyniophytes document critical transition from bryophyte-grade poikilohydry to true vascular homoiohydry during ini
Ref: Stewart & Rothwell Paleobotany 2nd ed., Ch Rhyniophytes; Taylor et al. Paleobotany