Drawdown

The silver lining to this year's prolonged dry spell is that it is a great year for looking at the flora of the drawdown zone around Skelton Lake (VC63 and 64). Most years, summer rain raises water levels again before things have had long enough to develop to their full potential.

Of course, my first port of call was to have the annual check on Grass-poly (Lythrum hyssopifolium). I could only find one, perhaps too dry for germination, but it might have a late flush with a bit of rain.

Grass-poly

It seems to be a really good year for Golden Dock (Rumex maritimus), and their are carpets of thousands of Mudwort (Limosella aquatica). Both present in the same corner of the lake as the Grass-poly as well as along the eastern shoreline.

Golden Dock

Carpet of Mudwort

Moving on, there was a cobble bar exposed in the river. In the absence of the usual dog walkers and swans it was worth an explore, and proved very rewarding. There were a surprising number of Tomato plants (Solanum lycopersicum), at least until considering the location downstream of the outfall for the Knostrop sewage works. Also, large numbers of Fig-leaved Goosefoot (Chenopodium ficifolium) growing with Red Goosefoot (Oxybasis rubra) and the best find Striped Goosefoot (Chenopodium strictum agg. - this would key to C. striatum using Sell & Murrell and is the prevailing form locally). Like most goosefoots, the development of the stripes and red coloration on the latter species seems a bit hit and miss in Yorkshire, I suspect we just don't get enough heat for long enough.

Tomato

Striped Goosefoot

Another good find in the river was the riparian form of Pale Persicaria (Persicaria lapathifolia subsp. lapathifolia) - easily mistaken for a more exotic species if not aware of how different it looks from the typical arable field form (subsp. pallida). It comes up around Skelton Lake most years and it is always nice to meet this graceful plant again, with its drooping flower heads, spotty stems and 'knobbly knees'. Nearby there was an unusually pale form of Linseed (Linum usitatissimum), also well as a few Marsh Dock (Rumex palustris).

Pale Persicaria

Linseed

Back over to the lake, there were two final treats. Sunflower (Helianthus annuus) and Grey Fat-hen (Chenopodium pseudoborbasii). The latter is a controversial Sell & Murrell segregate, but I've seen this small species a lot this year and it seems to be widespread, distinct/distinctive (more so than the widely accepted Swedish Fat-hen, Chenopodium suecicum) with its grey colouration and leaf shape, and relatively uniform in morphology. Albeit, in the latter case, its worth noting there are two forms - single stem (f. pseudoborbasii) and branching from the base (f. ramosa). The two forms often occur in isolation, but sometimes they can be found together.

Sunflower

Grey Fat-hen

The Draw of Drawdown

Mike Wilcox sent me interesting news this week that left with me with mixed feelings. He had popped over to Skelton Lake, part of my local patch, and found Mudwort (Limosella aquatica) - a cracking find and the first for the Aire Valley (at least in living memory if not all time). I was pleased because I had been expecting and hoping that this species would turn up, tempered by annoyance that if my weekend walk had taken a slightly different route then I would have got it first!

So naturally I went for a look this weekend and to take a few pictures. In so doing, I was able to extend it even further into the VC64 part of the lake.

Mudwort habitat

This really has been an exceptional year at this site, with water levels dropping consistently over the summer. In recent years rain in summer has re-filled the lake, putting an end to the drawdown season before it had fully got going. The Mudwort has joined the other recent cracking finds of Grass-poly (Lythrum hyssopifolium) and Golden Dock (Rumex maritimus).

A range of other species were putting on a good show. Including this really robust Persicaria. I really wanted this to be something different, it is so striking with its spotted robust stem, distinct nodes, multiple stems arising straight from the root stock and decumbent at the base, and sub-glabrous leaves. But I had to face facts, it was just a form of "Pink" Persicaria (Persicaria lapathifolium subsp. lapathifolium - in my view the circumscription of this in Flora Nordica seems more usable than the more recent one in Sell & Murrell, which under-describes the diversity of the two subspecies). Normally a plant this distinct and forming a distinct population would merit a name (of whatever rank), but the trouble with the Persicaria's is that they are autogamous, throwing up new variants which then breed true. Perhaps if its more widespread ... let me know if you've seen it elsewhere.

It was also nice to see the "Intermediate" Plantain (Plantago major subsp. intermedia), making its 2018 appearance on the strandline.

Unexpected, and again first seen by Mike, was this sunflower (Helianthus annuus).

All this, without mentioning the knotgrasses. That's a subject for another day, but as a taster, Polygonum microspermum. A delightfully dinky species with blue-tinged foliage and tiny flowers. Seems quite a reasonable split to me, especially when seen growing in the 100's.

VC64 End of Season Update

I have just finished crunching an excellent and large batch of records from Bruce Brown, who has been really active for the New Atlas in SE04, 05 and 06 over the summer. I'm looking forward to seeing what his efforts do for the stats on these hectads.

My personal choice of highlights include, starting with the natives:

The under-recorded reservoir drawdown specialist of 'Intermediate' Plantain (Plantago major subsp. intermedia) at Embsay and Grimwith Reservoirs. The latter also had Mudwort (Limosella aquatica), a very scarce species and one not recorded from that hectad recently. All photos mine unless otherwise stated.

 Plantago major subsp. intermedia

Limosella aquatica

Grimwith Reservoir also rewarded Bruce with two interesting hybrids, Shore Horsetail (Equisetum x litorale) and Myosotis x bollandica. There is a nice account of the latter with photographs here. Bruce also found the Myosotis on Crawshaw Moss, and the number of records of this hybrid in general are accruing with some regularity after its first description in 2012.

Bruce is well known locally for his interest in and knowledge of ferns. Finds this year include Oak Fern (Gymnocarpium dryopteris) and Beech Fern (Phegopteris connectilis) at Strid Wood. Neither fern is common in the VC,

Gymnocarpium dryopteris (photo by Griensteidl de Benutzer, Wikimedia Commons)

Phegopteris connectilis (photo by Griensteidl de Benutzer, Wikimedia Commons)

Other good finds include Small Teasel (Dipsacus pilosus) by the River Wharfe near Bolton Park, and Cloudberry (Rubus chamaemorus) at Thorpe Fell trig point.

Dipsacus pilosus

Moving onto non-natives. Bruce found the diminutive and probably much-overlooked Least Duckweed (Lemna minuta) in the pond at Embsay Nature Reserve. While at nearby Draughton he found Turkish Wood-spurge (Euphorbia amygdaloides subsp. robbiae). I have never understood why this is not afforded species status. Perhaps it will be one day so I am glad to have the record to subspecies level.

Euphorbia amygdaloides subsp. robbiae (photo by Dominicus Johannes Bergsma, Wikimedia Commons)

Another garden favourite occasionally found on road verges is Purple Crane's-bill (Geranium x magnificum), Bruce found this at both Embsay and Draughton.

Geranium x magnificum (photo by Meneerke bloem, Wikimedia Commons)

Mudwort's Moment

Mudwort (Limosella aquatica) is very much the plant of the moment, having been found at a number of sites in VC64 and neighbouring VCs over recent days. So if you have a reservoir near you with public access then its worth a search.

It is not a common plant nationally - see the excellent BSBI Database which now has open access to the maps, and perhaps use it to identify historic locations for targeted searches. I am sure it must still be present at most of the larger upland lakes and reservoirs. Following on from the last blog it has now been found for the first time at Eccup Reservoir (two new tetrads and one new hectad), Scar House Reservoir (new hectad) and Scargill Reservoir (first hectad record for decades). Please bear in mind that not all these sites have public access, there are plenty more reservoirs with public access worth searching. I would also love it if it was found in Huntingdonshire, where there are plenty of old mineral workings. It is much less common in that part of Britain, but it is known from similar habitats at Titchwell (VC32) so its not impossible and there are a number of very old records.

Mudwort in typical habitat by Scar House Reservoir (photo by Hannah Mitchell)

Part of the reason for recent finds is focussed searching at a time of year when botanical recording activities are winding down. I have been lucky enough to be doing reservoir surveys recently and have been getting my colleagues to keep their eyes peeled also.

Other associated highlights include a new population, and a large one at that, of Small Water-pepper (Persicaria minor) at Eccup. This a major range extension. Like the plants in the reservoirs along the Washburn valley, the plants are all white flowered. Eccup also provided 1000's of plants, enough to be certain it was not just a chance aberration, of an unusual form of Red Goosefoot (Chenopodium rubrum). This goes by the name of var. pseudobotryoides and is readily distinguised because the plants form prostrate to decumbent mats with small leaves. The stems upturn at the end where they produce short inflorescences. Stupidly, I took no photos but there is a picture here. Not the best botanical illustration but it is excellent for showing the general jizz of this variety.

The Draw of Draw-down

Draw-down, the seasonal exposure of sediments around the margins of ponds, lakes and reservoirs over the summer, is a habitat I always like to explore whenever I have the opportunity. It is as appealing to me as arable field corners, as you never know what you might find, and there can be much of interest in late summer when other habitats are winding down.

I have been lucky enough to get around a fair few reservoirs in VC63, 64 and 65 in recent weeks and have found plenty of surprises and also, to be honest, a fair amount of not so much. Its the boring sites that make the other sites so much more rewarding. Here are a few of the highlights.

Mudwort (Limosella aquatica) at Scargill Reservoir courtesy of my colleague Hannah Mitchell, also present at Swinsty and Fewston Reservoirs

Musk (Mimulus moschatus) on the mudflats at the northern end of Fewston Reservoir

A rather poor photo that does not do justice to this delicate species - Small Water-pepper (Persicaria minor var. minor). The whole population at Swinsty and Fewston is the unusual white-flowered form. The more typical pink-flowered form was encountered later at Leighton Reservoir

Not as rare as the preceding species, but it is always nice to see Water-purslane (Lythrum portula subsp. portula). 

Intermediate Plantain (Plantago major subsp. intermedia), a drawdown specialist unlike its weedy cousin Greater Plantain (Plantago major subsp. major)

And that's just a taster without mentioning Shoreweed (Littorella uniflora), Sand Spurrey (Spergularia rubra), Marsh Speedwell (Veronica scutellata), Red Goosefoot (Chenopodium rubrum), Monkey-flower (Mimulus guttatus) ...

You've probably noticed the recurring theme in most photos by now - the menace that is New Zealand Pigmyweed (Crassula helmsii). Please take care to clean your boots so as not to help it spread any faster than it is already managing, otherwise you get this ....

Fewston Reservoir, that really is all New Zealand Pigmyweed and this is but one small part of the infested shoreline of this large reservoir