Celatheca is a genus of extinct plants of the Early Devonian (Pragian, around 410 million years ago). Fossils were first found in the Posongchong Formation of eastern Yunnan, China. The leafless stems (axes) divided dichotomously but unequally so that one branch formed more of a 'main' stem and the other a side branch system. Side branches which did not bear spore-forming organs or sporangia divided two or three times further, ending in tips which curled back on themselves.