Welsh Journals

PLANTS OF DENBIGHSHIRE SAND QUARRIES T. EDMONDSON The tortuous course of the River Alun in Flint and Denbigh is bordered by deep deposits of sand and gravel which have been or are being excavated over a wide area. Glacial drift lies over Bunter sandstone and over a complex series of coal measures in East Denbigh. Terraces and post- glacial alluvium are additional features. The Wrexham-Gresford industrial complex straddles across the access routes to mid-Wales and north-east Wales from the Midlands. As might be expected, there is much of botanical interest although the vegetation patterns are incongruous on account of man's activities. Explorations of six sand workings in this region were profitable and yielded about 250 species. At most sites there were peripheral areas where loamy top soil had been disturbed, dumped or pushed to one side. Most of the forty or so species in such situations were typical arable weeds before the advent of clean crop seeds and biocides. Many plants were presumably from dormant seeds. Inevitably there were common taxa of oraches (Atriplex), mouse-ears (Cerastium), goosefoots (Chenopodium), spurges (Euphorbia), mayweeds (Matricaria), persicarias (Polygonum), docks (Rumex) and speedwells (Veronica). The common red poppies (Papaver dubium and P. rhoeas) were ubiquitous and often abundant as was the Wild Radish (Raphanus raphanistrum). The vehicular traffic is probably mainly local and no unusual aliens or colonists were noted. At two sites, excavations have stopped recently on reaching clay. The only permanent pool is in the early stages of colonisation by Bulrush (Typha latifolia), common species of water plantains (Alisma), willowherbs (Epilobium), rushes (Juncus) and so on. The Mare's-tail (Hippuris vulgaris) is a welcome early arrival. At the other site, a permanent spring has been struck at a lower level and the resulting channel has been colonised by the Small Pondweed (Potamogeton berchtoldii). Exposed base-rich clay, which is flushed or only periodically submerged, is favoured by Yellow-wort (Blackstonia perfoliata), Glaucous Sedge (Carex Jlacca), Common Spotted-orchid (Dactylorhiza fuchsii), Tall Fescue (Festuca arundinacea), Selfheal (Prunella vulgaris) and Coltsfoot (Tussilago farfara). There is a fine group of Wild Liquorice (Astragalus glycyphyllos) on one clay bank at Marford. This is probably native; the National Museum of Wales (NMW) has a 1923 specimen from the district. There are two good colonies of Bee Orchid (Ophrys apifera) and a little Blunt-flowered Rush (Juncus subnodulosus). On the old wooded banks surrounding the workings, the spring line at the junction of sand and clay is often delineated by lush growths of Great Horsetail (Equisetum telmateia), Hemp-agrimony (Eupatorium cannibinum) and Common Fleabane (Pulicaria dysenterica). The Common Centaury (Centaurium erythraea) occurs at all sites at the lower, damp levels where clay is mixed with sand. Only a little Trailing St. John's-wort (Hypericum humifusum) and Creeping WiHow (Salix repens) were found. On one such older but grassed level the Common Spotted- orchid has dominated in hybridisation with the Northern Marsh-orchid