Early Lockdown: Water-crowfoots, Water-starworts and Viola lactea

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Picture of Ranunculus aquatilis (Common Water-crowfoot)
Ranunculus aquatilis (Common Water-crowfoot)

Source: Hutson, Jacqui. “Early Lockdown: Water-crowfoots, Water-starworts and Viola lactea.” Sussex Botanical Recording Society Newsletter, no. 91 (November 2020). https://www.sussexflora.org.uk/wp-content/uploads/2022/02/Newsletter_nov_20.pdf.

22 March Early Lockdown walks had to be near home so we were limited to already well-known footpaths. One of these passed a chalk-stream-fed pond and I noticed it was covered with masses of Callitriche with long leaves. I did not recognise it as C. stagnalis (Common Water-starwort) so I retrieved a sample and took it home. I have never tried to identify Callitriche species because I have never found one with flowers or fruit, which were needed according to Stace. I examined the specimen but couldn’t find any flowers or fruit even with a microscope and the help of Stella Ross-Craig’s detailed drawings. I floated the specimen into a shallow tray of water and contacted Elisabeth Sturt with a photograph to ask advice. Elisabeth said that it looked like either C. platycarpa (Various-leaved Water-starwort) or C. obtusangula (Blunt-fruited Water-starwort) and to keep the sample captive in the hope that it produced pollen.

16 April I accompanied my husband, Tony, to our local sand quarry (no longer worked and partially flooded) where he has done regular bird counts. It is frequented by dog walkers and wild swimmers so I tend to avoid going there although it does have some good plants, including masses of the pale form of Ophrys apifera (Bee Orchid) in season. Tony said there was some water-crowfoot in some of the shallow pools. I took some photographs and a specimen – there were numerous plants spread over a large area. I used Stace to identify it at home. It took a while because I had a lot of difficulty in deciding whether the nectar pit was circular or not – it was surprisingly difficult to determine even with a microscope. I doubted my identification of the specimen as Ranunculus aquatilis (Common Water-crowfoot) because The Flora of Sussex suggests that it may be extinct in East Sussex. My specimen had only capillary leaves but the Plant Crib says that laminar leaves develop during the summer in response to long photoperiods.

17 April After sending a description and photographs to Nick Sturt and Nevil Hutchinson, who in turn sent them on to Matthew Berry and Mike Shaw, I was advised to ask the opinion of Richard Lansdown, BSBI referee.

18 April Great to hear from Richard that the record for R. aquatilis was confirmed (not extinct in East Sussex after all).

21 April In the past I had found non-flowering plants of a water-crowfoot on Chailey Common and I wanted to check the species, given that they should now be in flower. Early this morning I drove to Chailey Common to see what I could find (a couple of miles but had been reassured that it was OK to do this for exercise purposes as long as the exercise took longer than the drive). Heading for the largest pond on Pound Common I found it to be covered with masses of flowering water-crowfoot. I collected a sample and headed back to the car – recording a few plants on the way. These included numerous flowering individuals of Genista anglica (Petty Whin) in an area that seemed to have been cleared recently. By the side of a narrow path through low vegetation I saw some violets and kneeling for a closer look thought they must be Viola lactea (Pale Dog-violet) with their pale flowers and narrow triangular leaves. I didn’t collect any of course but instead told Paul Harmes. At home I identified the water-crowfoot as R. peltatus (Pond Water-crowfoot) and Nick was happy with that.

22 April Paul Harmes visited the violet site, had the identification confirmed, and took photographs that were far better than mine. The last records from Chailey Common were in 2011 in a different site.

7 May My captive Callitriche produced pollen at last, as Elisabeth had said it probably would, and she had sent me some useful scanned pages from Lansdown’s book re identification. Under the microscope the pollen grains were elliptical, measuring 50 x 25 microns. I told Elisabeth and she said the specimen must be C. obtusangula because it is the only one with such huge grains. Elisabeth suggested that I could amuse myself by looking for the stellate hairs/scales on young leaves and stems, which can help distinguish between some species. I did eventually find some at a magnification of x400 and by focusing up and down through squashed tissue. Very satisfying.

9 May Another local walk found Ranunculus peltatus colonising a recently dredged pond in an arable field on the nearby Hook Estate. That pond will be worth keeping an eye on.