The English bluebell, Hyacinthoides nonscripta and the Spanish bluebell, Hyacinthoides hispanica, are together known as bluebells. The bluebell which carpets the woodlands of the UK in spring is, of course, the English bluebell. It is the more delicate flower of the pair, with a blue-violet colour and flowers only on one side of the stem. The Spanish variety is slightly larger and has flowers evenly spaced around the stem, it is also the more invasive of the two. The English bluebell is under threat from the Spanish bluebell which is often mistakenly planted instead. The two easily hybridise and the hybrid then tends to push out the pure, native species, so don't plant Spanish bluebells in Britain!
There are other names for the English bluebell: Wild Hyacinth, Crawtraes (crow's toes), Granfer Griggles, Culverkeys (or Calverkeys), Auld Man's Bell, Ring-o'-Bells, Jacinth, Wood Bells, Scilla non-scripta and Endymion non-scripta. Confusingly the harebell, Campanula rotundiflora , is sometimes referred to as the bluebell, particularly in Scotland. It didn't help that some bright spark referred to the bluebell as the English harebell.
The flowers are six petalled, pendulous bell shapes arranged on the stem that grows from a bulb along with narrow, shiny leaves. The flowering period is early spring, to take advantage of the sunlight in the deciduous woodlands where it grows, before the leaves are fully formed on the trees and the canopy is closed over.
Whilst the English name is pretty self explanatory, the Latin name has a more interesting tale behind it; from the body of Hyacinthus, a Greek prince, grew bluebells. Apollo, who loved him and had sort of accidentally killed the lad, was understandably grief stricken so inscribed each of the bluebells with a tiny epitaph. As no such writing is seen on the English bluebell is was given the name non-scripta.
It is only in the UK that the bluebell forms the beautiful blue blanket during spring. It is not nearly as dominant on the continent. The reason for this is that during the last ice age, as the northern ice cap spread southward it pushed the temperate zone southward too. Eventually most of the woodland flowers were pushed out of the British Isles, all except the bluebell, which survived until the ice eventually receded. With all its competition gone from the island and unable to return over the English Channel, the bluebell was free to colonise the woodlands as it never could before, which is still the situation today.
The bulb of the bluebell is poisonous, with diuretic and styptic properties. It is not used in current modern medicine. In the past, the juices of the bulb have been used as a glue, both for book-binding and fixing the flights on to arrows.
http://www.botanical.com/botanical/mgmh/b/bluebe60.html
http://www.wildlifetrust.org.uk/sheffield/biodiversity/species/facts/bluebell.html