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Tuesday, 14 December 2010

New Plant Finds in the Mersey Valley, 2010




If anyone at all reads this blog regularly (is there anybody out there?) they may have noticed that I haven’t contributed as many articles to it this year, as I did last year – although there have been some excellent contributions from others.
The reason why I haven’t been so active here is because I’ve spent the Spring, Summer and Autumn botanising quite intensively and putting my records on to an electronic database (MapMate) so that I can share them with the Greater Manchester Ecology Unit and others. And what a year it’s been for remarkable finds! The other evening, members of the Manchester Field Club were invited to put together short presentations of around 20 photographs on subjects of their choice. Mine was entitled, ‘New Plant Finds, Mersey Valley, 2010’. It contained 23 or 24 photographs – but it could easily have contained twice as many! But in this article I’ll confine myself to my three best finds. All three of these plants are native species and they’re remarkable because, if you’d asked me about them last year, I would have said, off the top of my head, that all three were probably either extinct in the Mersey Valley or had not been recorded here before. So here are my accounts of the three plants:

Meadow Saxifrage (Saxifraga granulata) (Top photograph)

The word ‘Saxifrage’ means ‘stone breaker’. This is because most species in this genus are upland or alpine ones, which often grow out of cracks in rocks and cliff faces and give the impression that they are splitting the rock with their roots. In spite of this they are often very beautiful and delicate plants, much prized by alpine gardeners. I’ve seen some fabulous examples in the mountains of Eastern Europe. In Britain we’ve got about 17 or 18 species (including naturalised aliens) and some of the upland ones are among our rarest plants. Meadow Saxifrage (Saxifraga granulata), on the other hand, is atypical because it is often found in lowland meadows. Indeed it is now regarded as an indicator plant of unimproved grassland (now one of the rarest habitats in Britain).

In the mid 19th Century the great Manchester botanist, Leo Grindon reported in his book, ‘The Manchester Flora’ (1859) that Meadow Saxifrage was: “Plentiful about Mobberley, Ringway and Jackson’s Boat”, suggesting that it once grew in our local hay meadows. Nevertheless, Grindon’s contemporary, Richard Buxton, in his book, ‘A Botanical Guide’ (1849), has no local record for it – and as he didn’t appear to miss much, I can only conclude that Meadow Saxifrage was not common around here at that time.

Given this background and the fact that, in the contemporary Mersey Valley, anything vaguely resembling unimproved grassland has been reduced to a few tatty little scraps, I would have said that the chances of finding Meadow Saxifrage in 2010 were effectively zero (although I lived in hope). So imagine my amazement, one day last May, when I spotted two or three plants growing on the river bank on the Chorlton side of Princess Parkway! I don’t think my ‘flabber’ has ever been quite so ‘gasted’!

I thought that Grindon’s record was the last one before mine, but Dave Earle, who is the Botanical Society of the British Isles Vice County Recorder for South Lancashire (VC 59), tells me that there is a local record from 1950. But that still means that my record is probably the first for 60 years!

Common Broomrape (Orobanche minor) (Middle photograph)

Broomrapes are strange and sinister plants which are parasitic on other plants. Because they obtain all of their nutrients from their hosts they have no chlorophyll. There are 9 or 10 species in Britain, many of them rare or very rare. Most of these species are very host specific.

In Southern and Eastern Europe Broomrapes are much more common than they are here.

One species, Greater Broomrape (O. rapum-genistae), parasitises Broom and Gorse and has given its name to the whole group. Curiously, it is not called Broomrape because it ‘rapes’ its host but because the base of the plant is bulbous and turnip shaped; note that turnips belong to the species Brassica rapa.

Richard Buxton and Leo Grindon recorded instances of O. rapum-genistae in the Manchester area but they left no Mersey Valley records. Later floras (published in the 1960s/70s) suggested that this species is now extinct in the Manchester region.

I have not yet seen any records for Common Broomrape in the Mersey Valley. As a result I was stunned to find some specimens in East Didsbury back in July. The site was on the bank of a ditch not far from the river. I glimpsed, what appeared to be, a small vertical stick on the opposite bank of the ditch, under a tree, and knew instantly what it was. When I crossed the ditch I was able to find 11 plants in total. The only mystery is what were they parasitizing? O. minor is not as host specific as some other species but it tends to favour members of the Pea family (Fabaceae) and Daisy family (Asteraceae). But members of neither of these two groups were immediately visible. To complicate matters the Broomrape plants were growing amongst a patch of Ivy. There is a Broomrape specific to Ivy (O. hederae) but I don’t think that my plants were of that species. Ivy Broomrape tends to be confined to the Bristol area in Britain (and I have seen it there).

So, is mine the first ever record of O.minor in the Mersey Valley? And is O. rapum-genistae really extinct locally? I shall now have to check every Gorse and Broom bush that I see!

Common Storksbill (Erodium cicutarium) (Bottom photograph)

Storksbills are members of the Geranium family (Geraniaceae) but our four native species tend to be somewhat less common than many of their ‘true’ Geranium cousins. Three of these native species are almost exclusively seaside plants but Common Storksbill is found inland as well. Many members of the Geraniaceae have ‘beak-like’ fruits but those of Storksbills tend to be proportionately longer than those of Geraniums. It doesn’t need much imagination to visualise these fruits as storks’ beaks or bills (hence the common name).

In the 19th Century Richard Buxton found Common Storksbill, “... near Chorlton” - but didn’t elaborate further. Leo Grindon gave no specific Mersey Valley locations for the plant but wrote: “[It occurs] in cultivated fields and by dry waysides, but [it] is not a common plant”. This suggests that it might have been a rather scarce weed of cultivated fields around here.

In August of this year I found a single specimen of this plant near Northenden. The site was the area known as Kenworthy Woods. This is, essentially, a little bit of land left over from building the motorway and planted with Alders and other trees. Of course the authorities can’t leave any scraps like this alone (I suspect that they’re an affront to their ambition to concrete over as much of the planet as possible). So, in 2008, the Highways Agency (HA) dug part of it up to “improve the drainage”. These days the ‘concreters-over’ (probably much to their disgust) have to mitigate for any loss of biodiversity and so the HA has built a small pond in the middle of the site. Curiously, though, the most important effect of the disturbance was unintended. Last year and this year dozens of old agricultural weeds appeared, presumably because the seed bank was still in the soil and was brought to the surface by the disturbance. Poppies, Black Grass, Charlock, Stinkweed, Swine-cress, Field Penny-cress, Scarlet Pimpernel and several others appeared and flowered; but the ‘jewel-in-the-crown’ was Common Storksbill.

Unfortunately, the HA have scattered Perennial Rye Grass seed all over the site (Why? Why not let it re-vegetate naturally?). This grass already covers much of the site - which will soon be as boring as a suburban lawn.

Dave Bishop, December 2010

5 comments:

Polly said...

I read your blog! Very interesting too. Good plant-finding skills, well done!

Dave Bishop said...

Thanks Polly!

David said...

Dave,

Nice accounts of your new records and their historical and botanical significance - as usual.
This is an excellent collection of
general and botanical interest.

Best wihes and Happy Christmas!

David

d.aniel said...

Hi Dave,

I read your blog regularly and think it's great. Please keep it up - there are people out there.

Daniel

Dave Bishop said...

Thanks Daniel - more blog entries coming up!