Palæos:		Tracheophyta
PLANT EVOLUTION		Rhynia

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Rhynia gwynne-vaughanii

Rhynia gwynne-vaughanii
Class Rhyniopsida - Order Rhyniales - Family Rhyniaceae

Rhynia gwynne-vaughanii is a primitive vascular plant with branching leafless stems that reached a height of about 18 cm and culminated in fusiform-shaped sporangia. The upright stems branched from creeping branching horizontal rhizomes that bore delicate hair-like roots. The lateral branches could overtop the sporangia bearing stems, and the upright portions of the plant would have had a thicket-like appearance.. Small bumps along the stems may contain archegonia, which indicate a possible bryophyte-like life history, although this is still unclear. But there is also a distinct protostele composed of distinct phloem and only a handful of xylem cells.

The species is commonly present as monotypic stands, and seems to have been an early colonizer of well-drained sinter (hot spring sedimentary deposits) and sandy substrates. It is also found associated with all other Rhynie plants except (apart from very rarely) Horneophyton, suggesting that Rhynia was a vigorous, perhaps weed-like, form tolerant of a wide range of habitats and able to withstand interspecies competition within the Early Devonian ecosystem.

Links

Rhnia - from the Biota of Early Terrestrial Ecosystems: The Rhynie Chert - best on the web

The Rhynie Flora--Elaborations on a Theme - Rhynia

III. Rhynia and Aglaophyton - includes photographs showing details of microstructure

The Rhynie Chert and its Flora - VI. Growth Forms of Rhynia and Aglaophyton - includes photographs showing details of microstructure