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I think I can see 6 stamens making it Cardamine amara. How many do you see? Any further pictures?
...I was following a treecreeper at the time, so I only took the two pictures.
Can't make out the stamens myself but are those straight brown seedpods. I feel I would go for C.hirsuta but as MJB says any more pictures?
One thing I am still learning is you can never take enough photos of all angles and parts, especially leaves. Digital photos are free!
...doesn't necessarily make it C amara (and the flowers look much too small and white too). Some books say C flexuosa (wavy bitter-cress) has 6 stamens and C hirsuta has 4, however, Poland (the vegetative features book - so it is unusual that it describes flower features) says both can have 4, 5 or 6 stamens. So not a lot of help there! Also Poland uses stem thickness to distinguish between hairy (1mm) and wavy (2mm) bitter-cress, but I've got some in my garden that grade from 1 to 2mm, but I think they're all hairy bitter-cress.
Sorry that's not much help - but I've been trying to figure these out for the past week or so. Wavy bitter-cress is more likely in damper places, hairy in drier (eg my gravel path and as an abundant weed all over my garden).
I thought I had C. flexuosa in my garden, as well as C. hirsuta, but you've got me wondering now. Stace gives "stamens mostly 4" or "stamens mostly 6" to distinguish them, so I must remember to look at several flowers. I see what you mean about Poland. He gives a difference in the number of basal leaves that might help. I wish I hadn't weeded so efficiently now!
I think 6 stamens too, at least in pic 1. If so, wouldn't the pale anthers make it C. flexuosa?
Sorry, I meant C. flexuosa NOT C. amara! C. amara is large with purple anthers.
Well that makes two of us - I was thinking C pratensis when I referred to C amara...
Ah well. I've also been looking at the weeds in my garden again, and am now tending to go back to thinking that I have both C flexuosa and C hirta (and the stamens are mostly-6 and mostly 4 or 5 - but maybe it's linked to how healthy the plants are?
Counting basal leaves is pretty tricky even when one hasn't done too much weeding!
Lat/Lng: 52.0029, -0.4708
OS grid ref: TL050349
Flower found in a pretty soggy area