Showing posts with label Persicaria. Show all posts
Showing posts with label Persicaria. Show all posts

Monday, 15 August 2022

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


Sunday, 12 August 2018

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.






Wednesday, 12 August 2015

August Means Wetland Flora

As I've not posted anything for a few days, and as August is midway through the peak season for recording wetland and aquatic flora, I thought I would post something vaguely topical in the hope that it attracts a few more records or puts a face to a name for people interested in the variation present within species.

The robust form of Common Water-pepper (Persicaria hydropiper var. densiflora) is proving frequent in the margins of the River Great Ouse in Huntingdonshire, I am also finding it in similar habitats along the lower River Wharfe e.g. near Bolton Percy (VC64). It seems to cope with the more vigorous vegetation of river banks better than the less robust var. hydropiper (it would have helped to have a photo of this one also - a task for the next few weeks). It often occurs with some or all of the following relatives: Persicaria maculata, P. mitis and P. minor var. latifolia.

As the varietal name suggests it has a stouter inflorescence densely packed with flowers.