Botany - B.Ye. Yakubenko 2017

Part Three. The Plant Kingdom (Plantae)
Chapter VII. Systematics of Higher Plants
7.3. Division Rhyniophyta

The division Rhyniophyta comprises the most ancient, earliest vascular land plants, which likely emerged during the Silurian period of the Paleozoic era and became extinct in the Middle Devonian. The remains of these plants were first discovered in Canada back in 1855, and later found in Europe; however, it was only at the beginning of the 20th century that English paleobotanists R. Kidston and W. Lang thoroughly identified and described several genera of these primitive plants. Among them, the most detailed descriptions exist for the genera Rhynia, Cooksonia, and Psylophyt. Most likely, the asexual generation (sporophyte) was dominant in The life cycle of these plants.

Rhynia gwynne-vaughanii is one of the best-studied plants of this division. It was a herbaceous plant up to 50 cm tall with a stem diameter of 5–6 mm, which grew in marshy environments. Its aerial shoots branched dichotomously, and some of them bore sporangia at their tips. The shoots were leafless and are referred to as telomes. Subterranean telomes bore rhizoids. The telomes were covered by an epidermis with Stomata, beneath which lay a primitive Vascular System—a protostele consisting of phloem elements and tracheids. The sporangia possessed a multi-layered wall and produced uniform spores grouped in tetrads. Gametophytes have not been discovered.

Rhyniophytes are of great phylogenetic significance as an intermediate group between lower and higher plants, and as the ancestral Lineage that gave rise to The Development of other terrestrial plants, namely lycophytes, ferns, and possibly bryophytes.