Eohostimella heathana is an early, probably terrestrial, "plant" known from compression fossils of Early Silurian age (Llandovery, around ). The chemistry of its fossils is similar to that of fossilised vascular plants, rather than algae. Its anatomy constitutes upright, cylindrical tubes, with a thickened outer , which may have contained traces of lignin

Lignin

Lignin or lignen is a complex chemical compound most commonly derived from wood, and an integral part of the secondary cell walls of plants and some algae. The term was introduced in 1819 by de Candolle and is derived from the Latin word lignum, meaning wood...

 or a similar compound, even though no tracheid

Tracheid

Tracheids are elongated cells in the xylem of vascular plants that serve in the transport of water and mineral salts. Tracheids are one of two types of tracheary elements, vessel elements being the other. All tracheary elements develop a thick lignified cell wall, and at maturity the protoplast...

s or similar vessels have been found; the lignin-like compound was presumably associated with its thick outer cortex. It was probably affiliated with the rhyniophytes; it branched dichotomously and may have borne small spines.