Page "Transitional fossil" Paragraph 38

The Rhynia plant was small and stick-like, with simple dichotomously branching stems without leaves, each tipped by a sporangium.

The simple form echoes that of the sporophyte of mosses, and it has been shown that Rhynia had an alternation of generations, with a corresponding gametophyte in the form of crowded tufts of diminutive stems only a few millimetres in height.

Rhynia thus falls midway between mosses and early vascular plants like ferns and clubmosses.

From a carpet of moss-like gametophytes, the larger Rhynia sporophytes grew much like simple clubmosses, spreading by means of horizontal growing stems growing rhizoids that anchored the plant to the substrate.

The unusual mix of moss-like and vascular traits and the extreme structural simplicity of the plant had huge implications for botanical understanding.