Hairy or Wavy-how do you distinguish?
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Hairy Bittercress, an annual upto 30cms, leaves hairy above, flowers Feb/Nov & during in mild winters; with 4 stamens, pods extending beyond flowers.
Wavy Bittercress, biennial, taller upto 50cms, pods barely extending beyond flowers which appear April/Sept & have 6 stamens. (Fitter et al)
..unless you can catch it absolutely in flower at that moment, with all stamens present, and don't forget that 2 of the 6 (Wavy)are shorter than the rest.
(According to Rose, both flower 3-9, btw)
To make it worse, the stems of Hairy are often not straight (ie wavy) and the stems and leaves of Wavy are often hairy.
Wavy prefers damper places, Hairy will grow in drier environs, ie rocks, up walls etc.
If you have an upright stem, then you can count the stem leaves: Wavy has 4-7 stem leaves, Hairy has 0-4. But this depends on you finding a fully grown specimen.
If it's just the basal rosette, as you have here, it is very difficult to ID to species.
How to take close-ups with cheap phone and hand-lens:
Field Guides for Budding Botanists:
Agree, it is not easy without flowers.
I am guessing this is C.flexile from its jiz and the habitat clues. C.hirsuta is usually on disturbed ground (garden weed) and in exposed situations.
R M Walls
Lat/Lng: 51.3, -2.7
OS grid ref: ST5662