The cowslip flower heads each consist of seven individual flowers; some of these are shown from the back, but the rest are seen from the front, and so partially into the interior of the 'bell' of each flower. This needs to be a slightly darker yellow than the exterior, so I need to add some shading.
There isn't the space to do too much, so I've just used two colours. I added a band of stitches in the darker shade, Madeira 1406, just under the buttonhole-stitched rim of the bell:
Then a band using one strand of 1406 and one of 1405 in front of it:
And finally I filled in the rest of the flowers in split stitch in 1405:
Here are all three flower heads, completed:
Trying to get a shading effect into such small spaces was quite tricky, especially the smallest one, which is only about an inch (2.5 cm) across, so I'm quite pleased with how they've turned out. If I'd had the room, I'd probably have used three shades and made the difference between the yellow centre and the rest a bit more pronounced, but it just wasn't practical here.
There is one thing that's worrying me a bit though...