Dr Astrid Biddle

Looks right for R. Cavernosa. A dense coverage there. I'll look at the records later.

I don't know for John Warren's work. At Colney Heath, the Furze field heath area had field drains installed and the area ploughed for WW2 food production. There are a number of Herts areas where this was done. They were often reseeded for pasture.

The water levels are managed. Not a low level this year.

Only, don't go for black as you can't see it in silt.

I'd second that. It also fits into a small space, can be submerged, dropped in water, sat on, and mud washed off it.

I agree.
However, it also depends on what kind of mind you have. For me, it's a giant puzzle with complexities that blow my mind!

I saw these today in Herts.

#WildflowerHour
#ByTheSea
Not quite the sea, but Wilstone Reservoir, Hertfordshire. At the top of the drawdown zone, a vast carpet of Red Goosefoot (Oxybasis rubra) and the chunky Water Chickweed (Stellaria aquatica).

Popped it under the microscope to find the closest associate was Vaucheria sp(s) alga. I could see some oogonia, but the species wasn't identifiable, so I'm growing it on.
Best guess was V. frigida.

This is how it looked in 2022.

An episodic species seems to be appearing more often and this year, earlier. The spring drought may be the explanation, but water levels are also managed in the reservoir. I found that earlier this year, it had spread to nearby newly-created habitat too.

Riccia cavernosa at Wilstone Reservoir today.
An amazing amount of it! Many tiny thalli across the drawdown mud. Also, some thalli were much larger than I've seen here previously, usually only approaching that size in November.

Pollen viewed at x 200 with about 22% non-viable. Stained here with lactophenol cotton blue.

Extra petals in the buttercup (Ranunculus repens) provide a quick method to estimate the age of meadows There is a widely used crude method to estimate the age of hedgerows (Hooper's rule) based on species' richness. The aim of this study was to try and establish a similar field method for estimating th...

Fixed link: pmc.ncbi.nlm.nih.gov/articles/PMC...

Lots of Black Nightshade on my surveys.

Extra petals in the buttercup (Ranunculus repens) provide a quick method to estimate the age of meadows There is a widely used crude method to estimate the age of hedgerows (Hooper's rule) based on species' richness. The aim of this study was to try and establish a similar field method for estimating th...

Trying again: pmc.ncbi.nlm.nih.gov/articles/PMC....

Not found in the surrounding area, is this an ancient event that has been stored away for 100 years?

pmc.ncbi.nlm.nih.gov/articles/PMC....
Thought to be the accumulation of somatic mutations in a species that primarily reproduces vegetatively.
These were clearly an inherited characteristic, and more likely a variety.

Found in two resurrected Ghost ponds on Colney Heath: a double form of Creeping Buttercup (Ranunculus repens var. degeneratus) from separately seeded plants.
Then, I remembered John Warren had done a "count the petals on a Buttercup" to find the oldest UK meadows.

I'm growing this at home, and the leaf widths seem to vary according to how submerged they are. Slugs grazed the leaves off and all the regrowth is very narrow. I grew my material from seeds collected in Finland.
Now keeping the slugs off to get it to flower.

Russian Comfrey (Symphytum × ⁠uplandicum) which in the urban wetland manages to hold its own against False Oat-grass, Nettles, and nearly against Giant Bramble (Rubus armeniacus). I think Pendulous Sedge (Carex pendula) is its main adversary locally in Herts.

Then, there was Sea Club-rush (Bolboschoenus maritimus) in non-coastal Milton Keynes! Far from salt or shore, and on the lake-side with a selection of likely introductions.

Orange Balsam (Impatiens capensis) on a lake side. When I first learnt its name, I thought of this as the "Capri Sun" of the Balsms. Strange-yes, but I've never forgotten its name.
A neophyte like I. glandulifera. I find it quite widely distributed but not as invasive as it's flamboyant cousin.

Fantastic news James! Congratulations.

With little spring rain and recent warm weather we are seeing blooms of Blue-green Algae.
In Bucks last week and found the curly Dolichospermum circinale, looking like a microbial charm bracelet.
Heterocysts spherical 9 µm.
Alkanete 14 µm wide, 22 µm long.
Common Spike-rush & Water Dock nearby.

The surprising appearance of Riccia cavernosa (Ricciaceae) in North American pavement cracks | Request PDF Request PDF | The surprising appearance of Riccia cavernosa (Ricciaceae) in North American pavement cracks | Urbanization alters and homogenizes species distributions but can unexpectedly create new n...

I've been having a look at R. cavernosa, so interesting to see another site for it. I had a new site for it local to me in Herts last winter. I wonder if we'll see it as a pavement weed in the UK?
www.researchgate.net/publication/...

Is this the same R. cavernosa reported about ten days ago from a newly dug pond? Does it happen to be a known population?

I found this on the goose zone of a very large pond, so it seems likely to have originated as a birdseed alien too. The issue with feeding the geese here was not only the seed, but also their contribution to the growth of blue-green algae in the water. I'm identifying the algae later.

I think I remembered this plant from a post by @jo-the-botanist.bsky.social last year.‬

Ragweed (Ambrosia artemisiifolia) in Milton Keynes today. A plant which when flowers, produces a highly allergenic pollen. A single plant, and I'm now wondering if I should have pulled it up.
Frost sensitive and from the Americas.