Llanelli Naturalists Newsletter - Winter 1992/1993
George Hutchinson
Eleven members arrived for this late summer afternoon field meeting to record the rich weed flora of this rapidly changing area of the Borough, in fact so much so that the venue at the bottom of New Dock Road had been demolished and cleared only a few days earlier. The mild calm day with hazy sunshine allowed the flowers to open making them easier to detect. Recording was in 555198 and 555199 (tetrad 59E).
Yellow was the dominant flower colour, mostly of crucifers and umbellifers. Hoary Mustard Hirschfeldia incana was widespread, the small fruit tight to the long, curved branches. The species is native around the Mediterranean but it has spread rapidly in South Wales in the 1980's as an alien, and is found especially on disturbed ground in the industrial areas. However, its small yellow flowers were no match for the large brighter yellow petals of Perennial Wall-rocket Diplotaxis tenuifolia, easily checked by the foetid leaves, hence its alternative name, the "burnt-rubber plant". Wild Parsnip Pastinaca sativa contributed to the yellow theme at the meeting point. The group then crossed over to the corner of New Dock Road to look at garden escapes including a patch of a rich orange-flowered small marigold, later identified as a dwarf cultivar of Calendula officinalis. A tall goldenrod growing nearby had gone oyer apart from one inflorescence. Its storked capitulae (flower heads of Compositae) and glabrous (hairless) upper stem, made it the Early Goldenrod Solidago gigantea which flowers in mid August, a few weeks before the more frequent Canadian Goldenrod S. canadensis with its hairy upper stem. Here, Sweet Alison Lobularia maritime occupied its typical niche as a kerb weed.
Red Bartsia Odontites serotinus (=0. yerna) was found here but better plants were seen across the road, near planted White Poplar Populus alba, growing with Mugwort Artemisia vulgaris and Tall Melilot Melilotus altissima, the latter with hairy fruit distinguishing it from the scarcer M. officinale which has glabrous fruit. One had to check this carefully with a tiny X 10 hand-lens, an aid essential for a field botanist but rarely possessed by members attending botanical field meetings, yet bird-watchers are correspondingly rarely without their far more expensive, heavier and less portable binoculars. The hand-lens makes plant identification far easier. Common Broomrape Orobanche minor had been seen here a few weeks earlier but was not refound having become smothered by taller grasses which had grown up after the very wet August.
Heading south-eastwards, the party traversed the large area of cleared waste-ground. Pale Toadflax Linaria repens and Common Toadflax L. vulgaris grew close together, and it was a good area to identify the different yellow composites: Smooth Hawk's-beard Crepis capillaris with its distinct short outer and long inner phyllaries (the "green sepal area' on composites); Lesser Hawkbit Leontodon taraxacoides, with tiny Y-shaped forked tips to the leaf hairs and a not very hairy unbranched stem. Rough Hawkbit L. hispidus is similar but with a densely hairy stem and a larger capitula. It was only seen once. Autumn Hawkbit L. autumnalis, with its branched stems showed two growth forms - one with the normal deeply divided basal leaves with long narrow lobes, and a scarcer form with almost entire narrow glabrous leaves. Cat's-ear Hypochaeris radicata was frequent, with branched stems and frequent unbranched hairs on the leaves. Japanese Knotweed Fallopia japonica was in full flower at the northern edge of the infilled Great Western Dock. The taxonomy and genetics of this plant and its relationship to the Russian-vine Fallopia baldschuanica of gardens were discussed.
The group turned west and examined the prolific weeds on the embankment of a new road. Redshank Polygonum persicaria and Pale Persicaria P. lapathifolium grew together, the latter with the upper stem covered in yellow-green glands. Prickly lettuce Lettuce serriola had gone over but the whole plant still oozed a white latex which contains a bitter principle (as does lemon). The greenish-white stem and midrib to the leaves were typical of the species.
This was a good area to study the chenopods (goosefoots and creches). Fat-hen Chenopodium album occurred, and to the west side of the road a large area of Atriplex (the chenopods with a pair of small leaf-like bracteoles surrounding each flower). Spear-leaved Orache Atriplex prostrate was dominant forming a dense tangle with occasional Common Orache A. patula. The coastal Grass-leaved Orache A. littoralis seen a month earlier could not be found, seemingly swamped out. A Clouded Yellow was disturbed among the oraches, a migratory butterfly having one of its best years in the County. The yellow-flowered Fennel Foeniculum vulgare was seen, and leaves smelt, at the northern end of the oraches.
Small plants of Sea Aster Aster tripolium with its Leathery leaves, showed only its disc florets here; it was not until everyone looked down into the north side of the tidal Afon Dafen that plants with purple ray florets could be seen. A few plants of a glasswort Salicornia ramosissima with its relatively short terminal spike managed to survive among the creches. Recent work suggests that this glasswort and S. europaea are not distinct. (See the Summer 1991 and Winter 1991-2 issues of the Llanelli Nats. Newsletter for more details of Salicornia in Carms).
The various vegetation zones of the tidal Afon Dafen, which once channelled ships to the Great Western Dock, could be clearly seen. Another glasswort, Salicornia dolichostachya, with its long terminal spike, grew out on the bare mud but with Common Cord-grass Spartina anglica starting to colonise the same area; the latter's origins in Southampton Water, and cytology were discussed. Sea-purslane Halimione portulacoides formed a tightly packed grey band surrounded by Sea Beet Beta vulgaris spp. maritime and Annual Sea-blite Suaeda maritime. A fruiting plant of the endozoochorous Tomato Lycopersicon esculentum in the bed of the silted-up channel next to a sewage outfall prompted the party up onto drier land where an unusual immature composite had to be identified on a later visit as Sunflower Helianthus annuus.
It was time to move round to the south side of the Afon Dafen to inspect recently tipped mounds of earth and rubble, behind which, orange and yellow flowered pot marigolds (Calendula officinalis cultivars) lit up this drab area. Associated species were Flax Linum usitatissimum, Common Ramping-fumitory Fumaria muralis ssp. boraei, Field Woundwort Stachys arvensis, and Black Nightshade Solanum nigrum. Also, the uncommon labiate Cut-leaved Dead-nettle Lamium hybridum was determined later. Old undisturbed waste-ground nearby had established colonies of Bracken Pteridium apuilinum and Willow Salix. Rusty Willow Salix cinerea ssp. oleifolia, with its rusty hairs on the underside of the obovate leaves, was examined, growing with Goat Willow Salix caprea with its dark green broad-rounded leaves with white downy under-surfaces, soft to the touch. Double-flowered Soapwort Saponaria officinalis flore pleno blossomed in adjoining coarse grass.
Further east it was a surprise to find below us yet another tidal inlet, a relic of the Scouring Basin for the Great Western Dock. Bulrush Typha latifolia and Common Reed Phragmites australis formed small stands. Richard Pryce climbed down the steep bank to examine a large bed of white flowers which turned Out to be Water-cress Rorippa nasturtium-aquaticum. Common Couch Elymus repens was also identified - by far the commonest couch of the coastal fringes of Carms., often forming a narrow zone along the strand line. The spikelets often have protruding hair-like awns. White Willow Salix alba dominated the skyline at the side of an old pavement above the basin.
It was time to return to the cars, with a second chance to see and identify species observed elsewhere earlier in the afternoon. The highlight of the walk back along the new road was the crucifer Common Pennycress Thlaspi arvense with its attractive large orbicular fruit, broadly winged with a deep notch at the apex. The tiny fruit of the related Shepherd's Purse Caosella bursa pastoris could be compared nearby. Thyme-leaved Sandwort Arenaria serpyllifolia subsp. leptoclados and a flat rosette of Field Horsetail Equisetum arvense were also noted. The leader was thanked by Mr Denys Williams and the meeting ended at 4.45 pm with the party grateful that the forecast driving rain never materialised.
