Hyacinthoides Heist ex Fabr.
Hyacinthoides is a small genus which traditionally accommodated three to five species. However, recent molecular phylogenetic research (Grundman & al. 2010) accepts 11 species, some of which had not been combined before within the genus Hyacinthoides (mainly North African taxa that are of no concern here). It now includes some species that were previously included in Scilla L. A single species is native in at least part of Belgium, H. non-scripta (L.) Chouard ex Rothm. (Lambinon & Verloove 2012). It is sometimes also cultivated for ornament, although its cultivation apparently is less easy than that of other species of the genus (Tison & de Foucault 2014). Records outside its native Belgian distribution range (as garden escape) are not rare but confusion with the much more widely grown Hyacinthoides xmassartiana is likely.
Beside the taxa currently found in Belgium an additional taxon is included in the key beneath, i.e. Hyacinthoides italica (L.) Rothm. (syn.: Scilla italica L.). It has been reported as garden escape in neighboring countries. For convenience, a widely grown species from the morphologically similar genus Hyacinthus (Hyacinthus orientalis L.) is also included.
1 Tepals fused at base, at least for 1/5 of their length. Pedicels subtended by one inconspicuous bract === Hyacinthus orientalis
Tepals free or fused at extreme base only. Pedicels subtended by two conspicuous, unequal bracts === 2
2 Perianth 5-8 mm long, tepals widely spreading (almost stellate). All stamens inserted at extreme base of perianth === Hyacinthoides italica
Perianth at least 10 mm long, tepals erect or slightly spreading (tubular or campanulate). Outer stamens inserted at about the middle of the perianth === 3
3 Inflorescence 1-sided, pendent at apex. Flowers strongly fragrant. Perianth tubular, tepals 6-16 mm long. Anthers pale yellowish (cream), even before anthesis. Leaves (2-) 3-10(-16) mm wide (native) === H. non-scripta
Inflorescence not 1-sided, erect at apex. Flowers not or weakly fragrant. Perianth campanulate, tepals 13-23 mm long. Anthers blue or bluish before anthesis (but becoming yellowish at anthesis!). Leaves always wider, widest leaves rarely less than 10 mm wide === 4
4 Flowers odorless. Anthers blue before anthesis === Hyacinthoides hispanica
Flowers slightly (but definitely) fragrant. Anthers bluish (blue with cream) before anthesis === H. xmassartiana
Literature:
Adolphi K. (1977) Zur Unterscheidung von Hyacinthoides non-scripta (L.) Chouard und Hyacinthoides hispanica (Miller) Rothm. Gött. Flor. Rundbr. 11: 33-34.
Adolphi K. (1995) Neophytische Kultur- und Anbaupflanzen als Kulturflüchtlinge des Rheinlandes. Nardus 2: 1-272.
Grundman M., Rumsey F.J., Ansell S.W., Russell S.J., Darwin S.C., Vogel J.C., Spencer M., Squirrell J., Hollingsworth P.M., Ortiz S. & Schneider H. (2010) Phylogeny and taxonomy of the bluebell genus Hyacinthoides, Asparagaceae [Hyacinthaceae]. Taxon 59(1): 68-82. [available online at: https://www.researchgate.net/publication/233580939_Phylogeny_and_taxonom...
Jäger E.J., Ebel F., Hanelt P. & Müller G. (eds.) (2008) Rothmaler Band 5. Exkursionsflora von Deutschland. Krautige Zier- und Nutzpflanzen. Springer Verlag, Berlin: 880 p.
Lambinon J. & Verloove F. (avec coll. Delvosalle L., Toussaint B., Geerinck D., Hoste I., Van Rossum F., Cornier B., Schumacker R., Vanderpoorten A. & Vannerom H.) (2012) Nouvelle Flore de la Belgique, du Grand-Duché de Luxembourg, du Nord de la France et des Régions voisines (Ptéridophytes et Spermatophytes). Sixième édition. Jardin botanique national de Belgique, Meise: CXXXIX + 1195 p.
Leslie A.C. (1986) Hyacinthoides. In: Walters S.M. & al. (eds.), The European Garden Flora, vol. 1. Cambridge University Press, Cambridge: 214.
Page K.W. (1998) Hyacinthoides. In: Rich T.C.G. & Jermy A.C. (eds.), Plant crib: 374. BSBI, London. [available online at: https://bsbi.org/identification]
Pilgrim E. & Hutchinson N. (2004) Bluebells for Britain: the report of the 2003 Bluebells for Britain Survey. Plantlife, Salisbury, UK. [available online at: https://www.plantlife.org.uk/application/files/6014/8155/5822/Bluebells_...
Speta F. (1987) Die verwandtschaftlichen Beziehungen von Brimeura Salisb.: ein Vergleich mit den Gattungen Oncostema Rafin., Hyacinthoides Medic. und Camassia Lindl. (Hyacinthaceae). Phyton (Austria) 26(2): 247-310. [available online at: http://www.zobodat.at/pdf/PHY_26_2_0247-0310.pdf]
Stace C. (2010) New flora of the British Isles, 3th ed.: XXXII + 1232 p. Cambridge University Press.
Tison J.-M. & de Foucault B. (coord.) 2014) Flora Gallica. Flore de France. Editions Biotope, Mèze : xx + 1196 p.