Symphytum xuplandicum Nyman (incl. S. asperum Lepechin, S. xcaeruleum Petitmengin ex Thell.; S. asperum x S. officinale) (SW-As.) – A rather rare, locally naturalized escape from cultivation (formerly introduced for forage, more rarely as an ornamental). Known since 1884 from the surroundings of Leuven (Korbeek-Loo, Pellenberg) and still present in the valley of river Dijle at present (Verloove 2002, 2006). Several other locations are also well-documented. Known for instance since at least 1950 from Oudergem (Zoniënwoud), since 1974 from the nature reserve De Fonteintjes near Zeebrugge,… As a naturalized alien Symphytum xuplandicum is most often found in ditches and road verges. Occurrences on dumps and waste land are nearly always ephemeral.
Symphytum xuplandicum is a fertile hybrid. It was formerly cultivated for forage but some populations probably arose as a result of a spontaneous hybridization between native S. officinale and S. asperum.
Symphytum xuplandicum is here treated in a very broad sense as to include S. asperum and its back-crosses with native S. officinale (S. xcaeruleum). On the basis of herbarium collections (for instance from Zeebrugge) we have been able to prove that pure stands of Symphytum asperum ultimately change in stands of S. xuplandicum and/or S. xcaeruleum, whenever S. officinale is also present (as usually is the case). All these (notho-) taxa intergrade and specific limits have become obscure in Belgium. Pure populations of Symphytum asperum may be very rare in Belgium at present. It has sky-blue corollas, unwinged stems, a smaller calyx (3-5 mm), distinctly reticulate, dull nutlets and is very hirsute hairy (see Lambinon & Verloove 2012 for additional characters and its separation from S. xuplandicum).
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Selected literature:
Bäsler A. (1972) Cytotaxonomische Untersuchungen an der Boraginaceen - Gattung Symphytum L. Untersuchungen an Überwiegend norddeutschen Pflanzen der Arten S. asperum Lepech, S.officinale L. und S. x uplandicum Nym. Bot. Jahrb. Syst. 92: 508-553.
Bomble F.W. (2013) Symphytum bohemicum, S. officinale s. str., S. ×rakosiense und S. uplandicum s. l. im Aachener Stadtgebiet . Veröff. Bochumer Bot. Ver. 5(5): 44-60. [available online at: http://www.botanik-bochum.de/html/publ/OVBBV5_5_Bomble_Symphytum_Aachen.pdf]
Duvigneaud J. (1990) Quelques observations floristiques effectuées à proximité du château de Houx (Yvoir, province de Namur, Belgique). Nat. Mosana 43(1): 10-14.
Gadella T.W.J. (1978) Variatie en hybridisatie bij enkele taxa ven het genus Symphytum. Gorteria 9: 88-93.
Gadella T.W.J. (1983) Cyto- and chemotaxonomical studies on the sections Officinalia and Coerulea of the genus Symphytum. Bot. Helv. 93: 169-192.
Gadella T.W.J. (1990) Hybridization in Symphytum: pattern and process. Sommerfeltia, 11: 79-96.
Gadella T.W.J. & Kliphuis E. (1969) Cytotaxonomic studies in the genus Symphytum, 2. Crossing experiments between Symphytum officinale L. and Symphytum asperum Lepech. Acta Bot. Neerl. 18: 544-549.
Gadella T.W.J. & Kliphuis E. (1971) Cytotaxonomic studies in the genus Symphytum, 3. Some Symphytum hybrids in Belgium and the Netherlands. Biol. Jaarb. 39: 97-101.
Gadella T.W.J. & Kliphuis E. (1975) Cytotaxonomic studies in the genus Symphytum, 7. Some hybrids between S. asperum Lepech. and S. officinale L. in Denmark. Proc. Kon. Ned. Akad. Wetensch. C. 78: 182-188.
Gadella T.W.J. & Kliphuis E. (1984) Population variability, hybridization and introgression in Symphytum officinale in the Netherlands. Bot. Jahrb. Syst. 104: 519-536.
Huizing H.J., Gadella T.W.J. & Kliphuis E. (1982) Chemotaxonomical investigations of the Symphytum officinale polyploid complex and S. asperum (Boraginaceae): the pyrrolizidine alkaloids. Pl. Syst. Evol. 140(4): 279-292.
Huizing H.J., Malingre T.M., Gadella T.W.J. & Kliphuis E. (1983) Chemotaxonomical investigations of the Symphytum officinale polyploid complex and S. asperum (Boraginaceae): Phytosterols and Triterpenoids. Pl. Syst. Evol. 143: 285-292.
Jaarsma T.A. (1989) Chemotaxonomy of the Symphytum officinale agg. (Boraginaceae). Pl. Syst. Evol. 167: 113-127.
Kurtto A. (1982) Taxonomy of the Symphytum asperum aggregate (Boraginaceae), especially in Turkey. Ann. Bot. Fenn. 19: 177-192.
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.
Meyer M. (1972) Zur Unterscheidung von Symphytum officinale L. und Symphytum asperum Lep. Kieler Not. Pflanzenk. Schleswig-Holstein 4(2-3): 29-30.
Parnell J. (1985) Symphytum asperum Lepechin - a new Irish species. Irish Naturalists' J. 21: 498-499.
Rich T.C.G. & Jermy A.C. (eds.) (1998) Plant crib. BSBI, London: 391 p.
[available online at: http://www.bsbi.org.uk/Symphytum_Crib.pdf]
Verloove F. (2002) Ingeburgerde plantensoorten in Vlaanderen. Mededeling van het Instituut voor Natuurbehoud n° 20: 227 p.
Verloove F. (2006) Symphytum asperum. In: Van Landuyt W., Hoste I., Vanhecke L., Van den Bremt P., Vercruysse W. & De Beer D., Atlas van de flora van Vlaanderen en het Brussels gewest. Instituut voor Natuur- en Bosonderzoek, Nationale Plantentuin van België en Flo.Wer: 865.
Wade A.E. (1958) The history of Symphytum asperum Lepech. and S. x uplandicum Nyman in Britain. Watsonia 4: 117-118.