I got familiar with this species on the continent, where it became very abundant but seeing it near Doncaster on the railway tracks was quite a surprise – I had not seen it for quite a while now: it was like meeting up with a good old friend!
Senecio inaequidens, the narrow-leaved ragwort, is a fast spreading plants from Southern Africa that is mainly found in ruderal situations in Europe. It’s identification is relatively easy because it has the flowers of a ragwort (well, no wonder as it is one…) but it has very narrow leaves without any lobes (see picture below) and it has a stout fibrous stem. Keep your eyes peeled as it is likely to be under-recorded!
Transport networks such as railway and roads are often vector of spreading species. This is not only because vehicles transport seeds and other propagules but also because the transport network creates continuous novel habitats whose physical and disturbance conditions can strongly differ from the surrounding landscape.
Yet another interesting urban plant. I found Cystopteris fragilis, the brittle bladder-fern, thriving on old walls in the city of York. It is possible that improved air quality in the recent decades and a drastic reduction of acid rains is increasingly favouring this species and other alkaline-substrate-loving ferns such as Ceterach officinarum – rustyback – to grow on mortar in urban situations.
Urban flora fascinates me. One of the reasons is that the exceptional floristic diversity found in urban habitats challenges my ideas about wildlife and conservation. We tend to think of urban development as intrinsically adverse to biodiversity, however, re-colonisation can be quick and novel habitats can be rich and surprisingly biodiverse.
This positive aspect needs of course to be weighed up against irreversible loss of some habitats such as nutrient poor mires that can disappear and are never replaced.
But I also enjoy urban floras because so many unexpected plants turn up! and because it transforms my weekly trips to the supermarket into genuine botanical expeditions. Above and below are pictures of Filago vulgaris, the common cudweed, in a waste ground in (SK337889) Walkley, Sheffield, UK, near home. I had spotted the hundreds of tiny rosettes early this spring but couldn’t work out whether it would turn out to be a Filago or Gnaphalium uliginosum, the marsh cudweed.
There is much written about the spread of Polypodon viridis in Britain and Ireland but its close relative Polypogon monspeliensis may also be spreading. I am posting here a few pictures of P. monspeliensis, observed as a casual in a car park during my recent family holiday in Sussex (plants located at TQ452172). Note the resemblance with P. viridis inflorescences – apart from the long awns!
Last August, I was fortunate to be shown several ponds near Catcliffe and Treeton, East of Sheffield, UK, by Bob Croxton, form Sorby Natural History Society. The area is full of history and is a fascinating example of nature recovering following industrialisation.For instance, one of the ponds visited was formed in a lost piece of land amongst spoil heaps and three railway line! At this site Persicaria maculata and Nymphoides peltata were in full bloom (see picture) and two Potamogeton species were observed, now confirmed as P. pectinatus and P. pusillus. However only one shore was prospected and other nice aquatic plants are likely to be present in the rest of the pond.
On the whole, too many of the water bodies in the area were absolutely dominated by Elodea nuttallii, an invasive species that colonised the UK from the 1970s. It’s phenomenal spread in Britain and Ireland is summarised in a paper by Simpson that can be read from the BSBI archives. It remains unclear whether this spread has caused arm to aquatic biodiversity or whether it was simply facilitated by degraded habitats.
“As a contribution to the South-west Yorkshire (v.c. 63) Vascular Plant Red Data List, a population of Festuca altissima (wood fescue) was re-found at Forge Dam in the Porter Brook Valley, Sheffield, UK.
This population was first observed in 1991, when it was seen on “On steep shady bank by path” by Ian Rotherham with the grid reference SK303849. This record for F. altissima had remained overlooked by O. Gilbert who completed ecological work in the valley (Gilbert, 2001; 2003) as well as during the field recording undertaken in the area for the South Yorkshire Plant Atlas by Wilmore et al. (2010)(Ken Balkow, personal communication, 2013).
F. altissima is a rare grass in South-west Yorkshire where it is only know from four other sites, one in the same valley, two in the Sheffield area and one between Sheffield and Barnsley (Wilmore et al 2010).
It is not rare nationally but restricted in distribution by its narrow ecological preferences. It grows exclusively on steep slopes in shaded valleys on neutral to mildly alkaline soils and is believed to regenerate very slowly, i.e. to be sensitive to mechanical disturbance (Cope and Gray, 2009; Richards, 2013).
The Porter Dam population is located in or adjacent to SK30378492, on the South bank of the Porter Brook. There are approximately 40 individual plants, large and small, suggesting a healthy and dynamic population but, unfortunately, there is no indication of abundance associated with the 1991 record and as a consequence, it is not possible to ascertain any population dynamic through time.
The 40 plants are split equally into two groups by a large specimen of Prunus laurocerasus (Cherry Laurel) and there is no regeneration under the canopy of this shrub. Cherry Laurel appears to increasingly encroach this bank of the river, potentially threatening the local population of F. altissima.
In order to minimise the risk of extinction for this localised population, I contacted the concerned environmental stakeholders, the Sheffield City Council Ecology Unit and the Friends of Porter Valley. As a result the Friends of Porter Valley have volunteered to cut back the encroaching Cherry Laurel and monitoring will be undertaken in the coming years by myself.
The rest of the valley has not been searched for systematically for other populations of F. altissima and it cannot be excluded that other locality will be found in the future. The picture below shows the vegetative diagnostic character for the identification of F. altissima. These reduced leaf blades called cataphylls are of variable length and can be observed towards the base of the stem. Please refer to Cope and Gray (2009) or to Hubbart (1986) for a full description of the plant.
I am very grateful to John Poland, BSBI (Botanical Society of Britain and Ireland) referee for vegetative identifications, to confirm the identification of the plant material sent and to Ziggy Senkar and Ann Le Sage for taking interest in this botanical findings.
References cited in the text:
Cope, T. & Gray, A. (2009) Grasses of the British Isles, BSBI Handbook no. 13, Botanical Society of the British Isles.
Gilbert, O.L. (2001). Ecological survey of the Porter Valley. Sheffield : Friends of the Porter Valley.
Gilbert, O.L. (2003). Plants in the Porter Valley and their Ecology. Sheffield : Friends of the Porter Valley.
Below are some of my 2013 botanical findings in South Yorkshire as reported in the most recent Sorby Record, Sheffield. Note that they were also reported in the BSBI News no 125.
“Besides being a beautiful ornamental park, Whirlow Brook Park (North-east corner of SK3082) is home to naturalised populations of three noteworthy alien plants.
Corsican Toadflax (Cymbalaria hepaticifolia) is a striking ground cover or trailing plant similar to the well known Ivy-leaved toadflax (Cymbalaria muralis). It can be distinguished from it by its larger flowers, its larger leaves and the unusual silvery patterns following the veins on the surface of otherwise dark green leaves.
This toadflax can be seen on walls and in the rockery of Whirlow Park and it will be interesting to know whether it regularly produces fruits at this site.
Leptinella (Cotula squalida) is abundant in one of the lawns but being a very small plant, it can be easily overlooked.. The leaflets (about 10 of them on each side of the central nerve form altogether a compound leaf) look like miniature green hands or five-tooth combs for pixies, while the flower heads suggest delicate pompoms.
These two vascular plants are new records for Derbyshire, South Yorkshire and possibly for the Sorby area. Although very rare, their conservation value is relatively low as non-natives but it will be interesting to see if they spread and become regular members of Sorby-shire flora.
Another interesting discovery at Whirlow Park is the moss Atrichum crispum (a.k.a. Fountain Smoothcap), found by the pool and other water features at the bottom of the rockery. This moss resembles the very common Atrichum undulatum (Cathrine’s Moss) but unlike that species, it does not produce any capsules (fruits), its leaves are broader and not undulate, and they show only partly developed plates of green tissue on their upper surface.
These exciting features can be observed in the field with a hand-lens (I’d recommend a magnification of 15x or 20x). Atrichum crispum is believed to be a species introduced from North America where both male and female plants exist.
Because only male plants exist in Britain it is reasonable to assume that all individuals of this species are in fact only one clone, that colonised in Western Britain from a unique introduction!”