The photo above was taken in early April, but at that stage there were not many plants with flowers or leaves. The main flowering period is mid to late April.
Later in the year if you are lucky the blue fruits appear, these are edible and look like the supermarket fruit called Blueberries, although they are smaller.
The Bilberry is in fact a low growing shrub, it can get up to about 50/70cm in height, sometimes quite straggly in more shaded areas.
Since 2009, Bilberry in the UK has been succumbing to a fungal infection, Bilberry Blight, which turns the affected part of the plant brownish, so as to appear dead. It started in the far south of England, but is spreading, and is now affecting an area of moorland called The Roaches in the millstone grit area of the Pennines. Attempts are being made to stop it spreading.
The fruits contain various chemicals called anthocyanins which are useful in improving eyesight and night-vision and in delaying the onset of cataracts and other eye disorders especially AMD (age-related macular degeneration) which afflicts people over the age of 55 causing blindness starting from the central part of the vision first (unlike tunnel vision where the retina starts degrading around the periphery). The anthocyanins help to regenerate rhodopsin, a purple dye involved in night vision. So all you oldies, me included, get out there and collect and eat your bilberries.
Bilberries are the food plant of the rare Silurian Moth, these moths are very good at seeing in the dark. I have not seen any caterpillars on my plants but will keep an eye open for them in the future. See record of Silurian Moths in Monmouthshire. where they have been found in the Brecon Beacons
Thanks to British moths for the photo.. hope you do not mind me borrowing it. I will replace it with one of my own when I get one!