Easily mis-identified as :
Spanish Bluebell and the hybrid of English Bluebell with Spanish Bluebell, which is promiscuous around and near gardens, but both of those flare out sooner and wider than Bluebell and lack any tubular portion. Both
Spanish Bluebell and the hybrid have either paler blue flowers or are often pale pink or white. Spanish Bluebell not only has more flowers than (English) Bluebell but the stem is stouter and straighter without bending over, the flowers emerge from all sides of the stem and do not droop downwards.
Hybridizes with :
Spanish Bluebell (Hyacinthoides hispanica) to produce Hyacinthoides × massartiana, specimens of which have a spectrum of characteristics between the two parental extremes forming a so-called 'hybrid swarm'.
Some similarities to :
Squills such as Spring Squill,
Alpine Squill and
Siberian Squill but all those have more much more star-like open flowers which are not downwardly drooping.
Slight resemblance to :
Italian Bluebell (Hyacinthoides italica) but that has a shorter and conical spike of blue flowers, and occurs in just a few scattered hectads in England.
No relation to : Harebell [a blue flower belonging to the un-related Bellflower Family (Campanulaceae) which in Scotland are called 'Bluebells'].
The flowers are more trumpet-shaped than bell-shaped, but the name takes precedence. They have a slight sweet fragrance. Bluebells do not like to be in the full glare of the summer sun all day, and will only carpet relatively open and damp deciduous forests with dappled shade. The UK has about half the Worlds' population of Bluebells, being a particularly quintessential part of England. Moreover, the UK is unique in that in no other country does the bluebell form dense glades in open woodland. In that regard, although it may not be particularly rare in the UK, in the rest of Europe it certainly is, hence they are a protected species under European Law as an Atlantic species, of which the UK is a signatory.
However, not all our dense swathes of Bluebell are in woodland, some are most definitely in much more open ground, such as amidst the last years' withered bracken flowering and self-seeding well before the bracken re-awakens in late spring. In such locations it is not in dappled shade, but almost full sun.
Despite seeming so profligate, they are a rare and protected species and threatened by hybridization with
Spanish Bluebell, the hybrid, known as Hyacinthoides × massartiana, spreading much more readily than the Spanish parent. The hybrid is a serious threat to the Bluebell and forms what is known as a 'hybrid swarm' with a full spectrum of characteristics between Bluebell and
The black seeds germinate on the surface, but as they grow, the contractile roots keeps pulling the bulb further down into the earth until the bulb reaches as far as down as 12cm. This is one of the reasons it enjoys a soft woodland soil, and explains why it wont grow in hard or less deep soils.
MALONYLAWOBANIN - the Blue Pigment
When the flowers first emerge both stem and flowers are suffused with the deepest blue imaginable, a colour so deep that no current camera, file-format nor monitor screen can either capture, store nor portray the true colour with their very limited triangular colour gamut. All three: camera, file-format and monitor would perhaps require six different coloured pixels to be capable of capturing or representing the true colour; a technology that is nowhere on the foreseeable horizon. After a while the colour of the flower fades to a lighter tone of azure blue.
The colour was, until only recently, thought to be due to an
anthocyanin derivative: delphinidin 3-p-coumarylglucoside-5-glucoside, but it is now known that the blue compound within Bluebell is actually malonated. A new common name has been assigned to this novel compound,
Malonylawobanin, which is O-(6-O-(trans-p-coumaroyl)-β-D-glucosyl)-5-O-(6-O-malonyl-β-D-glucosyl)delphinidin. This blue compound is also present in the blue flowers of
Asiatic Dayflower (Commelina communis) from where it is extracted to be used as a blue pigment. Note that Bluebells themselves cannot be harvested for this blue pigment as they are protected under UK law and it is illegal to even pick them without the landowners consent.
The anthocyanidin Delphinidin is shown in blue, and is the compound responsible for the blue colouring in
Delphinium flowers as well as several other flowers. Attached to this are two glucosyl groups, shown in red. To one of these is attached a malonyl group (derived from
Malonic Acid) shown in green, and to the other a coumaryl group (derived from
Coumaric Acid) shown in orange. Several of these groups share the same oxygen atoms.
The structures below are to illustrate the individual components of Malonylawobanin; they are not reported to be present as separate entities within Bluebells.
Delphinidin is said to be the anthocyanidin present in
Violas, and is a blue pigment with anti-oxidant properties. It is also present in the berries of Cranberry. It is sensitive to pH, turning red in acidic solutions. Other glycosides of Delphinidin which are present in various other plants are Myrtillin (Delphinidin 3-O-glucoside), present in
Blackcurrants and in the berries of
Tulipanin (Delphinidin 3-O-rutinoside) which is also found in
Tulips and in the berries of
Blackcurrant and in species of Barberry; and Violdelphin (a complex glucoside with four sugar groups and two para-
HydroxyBenzoic Acid groups and which is responsible for the purplish coloration in
Chinese Aconite) and in blue flowers from the Campanula genus such as Peach-Leaved Bellflower.
Malonic Acid sits between Oxalic Acid and Succinic Acid, all of which are saturated di-carboxylic acids. Malonic Acid occurs in high concentration in Beetroots. Coumaric Acid is a hydroxycinnamic acid which should not be confused with Coumarin, an entirely un-related compound. The para-form of Coumaric Acid is shown above, and is the most naturally abundant of the three isomers that Coumaric Acid can exist in, being present in, for example,
Garlic. It is a major component of
A related blue pigment, the 3-p-coumarylglucoside-5-malonylglucoside derivative of Cyanidin, is present in several members of the Dead-Nettle and Mint Family (Lamiaceae). Here the blue structure is that of Cyanidin rather than Delphinidin (the only difference being the lack of one of the -OH groups on the blue coloured structure).
Compare with the Violdelphin anthocyanin found within blue species of Campanula such as
Canterbury-bells Campabula medium.
POLYHYDROXYLATED PYRROLIDINES & PYRROLIZIDINES
Bluebells also contain many polyhydroxylated
Pyrrolidines, which are analogues of sugars but contain nitrogen in the ring rather than oxygen, are potent glucosidase inhibitors. Because of all the hydroxyl groups around them they can get mis-identified as sugars within the mammalian body where they may wreak havoc on the system. Polyhydroxylated Pyrrolidines such as
Nectrisine (D-ABI or 1,4,-dideoxy -1,4-imino-D-arabinitol) and DMDP (2R,5R-dihydroxymethyl -3R,4R- dihydroxypyrrolidine). DMDP is also found in a tropical bean from Costa Rica where it is cultivated and harvested for DMDP and used as a pesticide. They also contain many polyhydroxylated Pyrrolizidines such as
Hyacinthine C1 which is a moderate inhibitor of amyloglucosidase.
Polyhydroxilated Pyrrolizidines (not to be confused with the similarly spelled polyhydrozylated pyrrolidines) are also surrounded by numerous hydroxyl groups mimicing sugars, and these also may similarly be mistaken for sugars and gum up the works when ingested by mammals.
Altogether, 19 polyhydroxylated
pyrrolizidine alkaloids known as Hyacinthacines) have been isolated from five members of the Hyacinthaceae Family, being: Bluebell (Hyacinthoides non-scripta),
Garden Grape-hyacinth (Muscari armeniacum),
Siberian Squill (Scilla sibirica),
Wood Hyacinth (Scilla campanulata) and
Silver Squill (Scilla socialis), the latter two are non-native to the UK.
These Hyacinthacines are classified into three groups: A1-A7, B1-B7 and C1-C5, based upon the number of hydroxy groups on the first ring. The letter denotes no hydroxy groups on the first ring, thus A for no -OH groups on the first ring, B denotes one -OH group, whilst the C denotes two -OH groups on the first ring. The Hyacinthacines have parallels with the Calystegines, which are polyhydroxylated
Bluebells are known to cause cases of poisoning in livestock, and it is thought that compounds like the above are responsible, being glucosidase inhibitors.
BUFODENOLIDES (CARDIAC GLYCOSIDES)
Scillarens are a group of cardiac glycosides found in species of Hyacinthoides (Bluebells) and Scilla (Squills). They are poisonous, but because they are not absorbed in the gut very well, are not usually lethal. It is based on Hellebrin, another cardiac glycoside found in the plant Black Hellebore (aka Christmas-Rose) (Helleborus niger) [formerly Radix hellebori nigri].
Scillaren A has two sugar units attached,
Rhamnosyl (rha) followed by
Glucosyl (glc) and the cardiac effects are similar to those of the cardiac glycosides extractible from Foxglove apart from that its effects are of shorter duration. The Scillarens produce symptoms of copious diuresis. The cardiac action is often present when other cardiac glycosides such as those from Foxglove fail to act, or are in-sufficient, or where intolerance to
Digitalis exists. It has a high therapeutic index and is also rapidly elimination from the body; it is therefore able to maintain cardiac effects in those cases where prolonged treatment is necessary. It is a very useful pharmaceutical. Naturally, with Bluebell being such an endangered species, no pharmaceuticals are harvested from it, although it is possible that it is harvested from
White Squill aka
Sea Squill (Drimia maritima) [formerly Scilla maritima] or from
Red Squill (both non-native).
Scillaren A is also found in the non-native
Red Squill. The enzyme scillarinase can cleave off the glucose unit selectively leaving
Proscillaridin A which has just a rhamose sugar unit.
Scillarenin is the aglycone of both Scillaren A and Proscillarenin A and is also probably present. In any case, the sugar units will be removed from both Scillaren A and Proscillaridin A if ingested leaving Scillarenin.