Dr Astrid Biddle

@wildflowerhour.bsky.social Still flowering this week: Seaside Centaury (Centaurium littorale) at the edge of a dune slack pond near Southport.

An absolutely stunning place to be in the last days of September.

My last official plant survey of the season today. The last of the over 140 ponds I visited in England, from Cornwall to Northumberland. Here, finally in Bucks, I ended with Nitella flexilis agg. Another plant, & another new area record. My 4th record for this species in this county this year.

Hopefully, we'll be publishing my results for this pond set. And the Nitella! Is it a long-lived spore bank in the soil, or is it species mobility at the landscape scale? I feel so sad that autumn is with us now. I didn't want this year to end. So much to see! @bsbibotany.bsky.social

Dipped into Hatchet Pond this week to see what charophytes were there: stands of Nitella transluscens out beyond the Myriophyllum alterniflorum. In a hidden corner, a strand of Utricularia minor.

I was in N. Norfolk on Friday & early autumn produced the most exquisite day. Light was soft & colours glowed. Here was just some ordinary Pelia endiviifolia growing in a pond. A pond sited within heath, bordered by Molinia & yet with a chalky base. Just look at the jade beauty of this liverwort!

20 Sept

This made my heart skip a beat this week: Frogbit (Hydrocharis morsus-ranae) and Tubular Water-dropwort (Oenanthe fistulosa) growing in profusion side by side. They may have been planted in a garden pond, but nonetheless, what a triumph! Planted #WildflowerHour

20 Sept

I find it interesting to consider what Flowering-rush (Butomus umbellatus) material is grown & planted, and what the implications are. Diploid material is fertile & has narrower tepals. Triploids are infertile & has bigger flowers with broader tepals, and produce bulbils. That's what we have here.

20 Sept

Cape-pondweed (Aponogeton distachyos) is a magnificent and strange flower. A South African species, but another species planted in ponds and sometimes naturalised.

Branched Bur-reed brainteaser in Shropshire The broad, rounded fruits identify Sparganium erectum subsp. oocarpum, now treated as S. × oocarpum, a hybrid between S. erectum and S. neglectum. Partly sterile fruit heads provide a useful clue.

It's a really good time of year to look at Sparganium fruits as they become distinctive as they ripen and dry.

18 Sept

Out in the field today and revisiting the S. erectum complex. L: x oocarpum R: erectum s. str. (I think these look like cupcakes)🧁

13 Sept

My #favouriteplant of 2026 has to be Isoetes phrygia, seen submerged in a temporary pool on the Omalos Plateau, Crete. A rather wonderful example of cryptic diversity—and, as a spore-producing quillwort, perhaps cheekily stretching the definition of #wildflowerhour!

13 Sept

A lovely example of cryptic diversity: quillwort species can look deceptively alike, with their differences hidden in microscopic characters. Proximal view at ×40; megaspore 550 µm. With no velum or phyllopodia, this is the amphibious Isoetes phrygia, neither terrestrial nor fully aquatic.

Here is Sparganium neglectum in Kent.

And S. erectum s.str. in Blackpool.

If you know, you know… Bend the inflorescence of Orange Foxtail (Alopecurus aequalis) over and check that there really are no awns. A really nice thing to find in the drawdown zone of a pond.

Common Water-starwort (Callitriche stagnalis) rushing to reproduce before the pond refloods. Fruit super-abundant, even on remarkably tiny plants. It seems able to fruit at a much smaller stage than the other Callitriche I usually encounter.

Winter annual Batrachium taking advantage of the drawdown. Its seeds need a period of drying before they germinate readily when the pond refills. Adapted to the pond's seasonal rhythm.

If you know, you know… Bend the inflorescence of Orange Foxtail (Alopecurus aequalis) over and check that there really are no awns. A really nice thing to find in the drawdown zone of a pond.

I’ve found Orange Foxtail in quite a few ponds this year. It’s a plant of bare mud exposed as ponds and other wetlands dry out, and I’m wondering whether the dry spring and unusually early drawdown have made it one of the winners of this drought year.

Amazingly large patches of Taper-leaved Earthmoss (Pleuridium acuminatum) across the sandy drawdown zone of a heathland pond. I don’t think I’ve ever seen quite so much of it.

Pleased to announce my new paper: Herbarium specimens spanning nearly two centuries revealed striking ecological & geographical differences between two ploidy-defined subspecies of Eleocharis palustris in Britain. Ploidy & genome size could help explain them. doi.org/10.33928/bib...

The project also reinforced how valuable herbarium collections remain as scientific resources. Historical specimens collected more than a century ago can still reveal overlooked biodiversity and entirely new ecological questions when revisited with fresh approaches. @bsbibotany.bsky.social

Many thanks to the many kind and generous people who helped me in my search. @nhm.org @cuherb.bsky.social @herbarium.bsky.social @rbgkew.bsky.social

What interested me most was that the story did not stop at taxonomy. The work raises questions about genome size, ploidy level, stomatal traits and ecological differentiation in wetland plants.

In Eleocharis, which possesses holocentric chromosomes, the relationship between genome structure and ecological behaviour may be particularly interesting.

By revisiting herbarium specimens from major UK collections, it became possible to reassess nearly 200 years of material using stomatal measurements taken directly from dried specimens.

What emerged was a striking ecological pattern. The lower-ploidy subsp. palustris appears strongly associated with coastal grazing marshes, tidal river systems and floodplain wetlands, and is far rarer in Britain than I had expected from the literature and recording data.

I thought these ponds were meant to be boring today! A massive patch of enormous Glaucous Crystalwort Riccia glauca rosettes on the drawdown at Dagnam Park, NE London.

Better known from arable and disturbed ground, but here behaving as an ephemeral drawdown species, taking advantage of the brief period of exposed, damp mud.

28 Aug

Today a scrap of Riccia fluitans in Surrey, clinging to moist decaying Typha, right in the middle of the pond. A needle in a haystack.

At Wimbledon Common today doing surveys. I remembered seeing a remarkable number of old Starfruit Damasonium alisma herbarium sheets from Wimbledon Common in the Natural History Museum collections. I loved how the plants that were virtually all seed and few leaves. Date was 17/8/1869.

They don’t say which ponds the plants came from. But looking at this drawdown today: yes. You can see it. Just remove urban stuff and add cattle... then BOOM!

19 Aug

After a succession of fairly uninspiring ponds, this was rather nice. Huge amounts of Blunt-leaved Pondweed Potamogeton obtusifolius, co-dominant with Elodea nuttallii and carpeting the bottom of one of the large ponds at Swanholme Lakes.