Glimpses of the botanical history of Wales

Abstract

The Ordovician through Carboniferous rocks of Wales and the Welsh borderland (c. 250 million years) have been central to elucidating the initial phases of the colonization of land by plants as they diversified from simple herbaceous organisms lacking leaves and roots to substantial forest trees. Spores extracted from Ordovician and younger rocks indicate that pioneering plants allied to mosses and liverworts were part of a vegetation composed of lichens and algae. Vascular plants today include ferns, horsetails, conifers, and flowering plants but their earliest fossils in Silurian and Devonian rocks, although possessing all the anatomical characteristics of today’s flora, had very simple architecture – essentially collections of green smooth stems and sacs of spores (e.g. Cooksonia). In time branching diversified and height and reproductive capacity increased. Only one group, the clubmosses, with small simple leaves, still exists, evolving into the gigantic trees that dominated Carboniferous swamps. Other members of the tropical forests included tall ferns and horsetails plus the earliest seed plants. The peat they produced was transformed into coal whose exploitation led to Wales’s global influence during the Industrial Revolution