Leader Ben Monk
The first field meeting of the year was blessed with a warm sunny day, a prelude to the unseasonably warm spring. Parking by the Pit Stop Café, 8 members went the short distance to the beginning of our walk where we were met by Ben Monk, one of the wardens of the Penllergare Trust (this is how the estate name was originally spelt), formed to manage and protect the area.
Our path followed the River Llan, quite steeply at first, through a mixture of Sessile Oak Quercus petraea and various pines Pinus spp. with substantial amounts of Rhododendron R. ponticum plus several other species collected from Asia – evidence that it is a man‐made landscape. The man responsible was Dillwyn Llewellyn, a Victorian pioneer of photography, scientist and plant collector.
There were a few clearings in which several species of butterfly were seen basking in the sunshine. These included Red Admiral Vanessa atalanta, Orange Tip Anthocaris cardimines, Speckled Wood Pararge argeria, Tortoiseshell and the magnificent Brimstone Gonepteryx rhamni. For many attending, it was the first time they had been seen this year
We made our way down to the Llan where further evidence of the man‐made nature of the valley was seen in the large stands of bamboo of three different species, amongst which was a Downy Birch Betula pubescens with a large gall half way up its trunk (see photo, left, and note 1) and, a first for me, a non‐invasive knotweed – Giant Knotweed Fallopia sachalinensis (note 2). These “foreigners” were surrounded by many spring flowers including Wood Sorrel Oxalis acetosella, Wood Anemone Anemone nemorosa, Marsh Marigold Caltha palustris and Common Dog‐violet Viola riviniana.
The party eventually reached the former boating lake where began the return journey on the other side of the river. Here we could hear most of the more common early migrant birds: Blackcap Sylvia atricapilla, Willow Warbler Phylloscopus trochilus and Chifchaff Phylloscopus collybita, along with Green Woodpecker Picus viridis and Grey Wagtail Motacilla cinerea. Also seen were Jew’s Ear fungus Auricularia auricularjudae on Elder Sambucus nigra and Maze‐gill fungus Daedalia quercina.
Ben explained more of the history of the valley showing us a couple of derelict lodges and disused quarries where stone for the former mansion (above the western side of the valley and now the site of the Swansea City Council offices) and many of the man‐made features such as the walls which contained the river and the waterfall. He also pointed out that this area close to Swansea was subject to antisocial behaviour such as vandalism and fires, motorcycling and irresponsible horse riding, yet despite this, it had provided the party with an interesting and lovely afternoon ramble.
This is believed to be a crown gall which is caused by Agrobacterium tumefaciens (closely related to Rhizobium which forms the nitrogen fixing nodules of legumes) and normally occurs nearer ground level. The organism is interesting as most of the tumour causing genes are carried not on the chromosomes but on a separate circle of DNA called a plasmid. These are capable of replicating independently in the cell and being transferred from one cell to another which has made them a useful tool in genetic modification of plants. Well known examples are the Flava Savr tomato, Roundup Ready soya beans resistant to glyphosate herbicide and crops such as maize, potato and cotton incorporating Baccilus thuringiensis (bt) toxin for insect resistance
This is Giant Knotweed Fallopia sachalinensis which has recently been included as an injurious weed as both male and female plants are known in Britain and due to its potential to hybridise with the ubiquitous but invariably male‐sterile Japanese Knotweed F. japonica var. japonica, to produce the highly invasive Fallopia x bohemica. The recently introduced biological control ‐ the psyllid Aphalara itadori, does not control Giant Knotweed