Leonurus cardiaca subsp. villosus

Leonurus cardiaca subsp. villosus, a long forgotten and probably neglected xenophyte in Belgium

Leonurus subgenus Cardiaca Benth. series Cardiaci V. Krecz. & Kuprian. is an assemblage of a few closely related species, including L. cardiaca L. (s.str.). The latter is a rare species in Belgium and probably an archaeophyte (Lambinon & al. 2004, Van Landuyt 2006). It was formerly widely introduced as a medicinal plant and readily escaped (which considerably blurred the boundaries of its native distribution area in Eurasia). Today it is still regularly cultivated in Belgian gardens.

In the past years the complex taxonomy of Leonurus cardiaca and related species was emphasized by Holub (1993; see also Loos 1995). Especially stem indumentum (and to some extent also leaf shape) proved to be worthy characters to separate a rather distinct Asian taxon, Leonurus cardiaca subsp. villosus (Desf. ex d’Urv.) Hyl. (syn.: L. quinquelobatus Gilib., L. villosus Desf. ex d’Urv., L. cardiaca var. villosus (Desf. ex d'Urv.) Nyman). It is distinguished by stems that are densely hairy throughout (with long patent hairs on the angles but also on the faces) and lower cauline leaves that tend to be more deeply lobed. By contrast, in Leonurus cardiaca, stems are nearly glabrous or have scattered, adpressed short hairs on the angles only (faces are glabrous) and lower cauline leaves are often less deeply lobed (rarely more than ½ their length (see Kupryanova 1977). Holub (1993) specified that in areas where both taxa grow sympatrically a very rare intermediate form occurs that he called Leonurus intermedius Holub.

Leonurus cardiaca subsp. cardiaca, Lanaken (Hochter Bampd), gravelly margin of river Maas, June 2010, W. Vercruysse

Years ago already part of the Belgian collections of Leonurus cardiaca were revised in order to check whether or not this taxon has been collected in Belgium. More than 10 collections from widely scattered localities indeed proved to belong with the latter and the species was accepted by Verloove (2006). Surprisingly, Leonurus cardiaca subsp. villosus was already collected in the surroundings of Tournai nearly 200 years ago! Standard floras in the 19th century were aware of this taxon and named it L. canescens Dum. (Durand 1899). An overview of all examined specimens is given below (per province):

Hainaut: Tornacum (= Tournai), <1827, Dumortier s.n. (BR); Baudour, bord du bois, 07.1892, A. Brabant s.n. (BR); Ogy, friche nitrophile près de l’église, 07.1979, P. Meerts s.n. (BR);

Limburg: Lanaken (IFBL E7.14), s.d., Dumortier s.n. (BR); Genk (IFBL D7.41), mur du cimetière, 07.1911, R. Naveau s.n. (BR); Genk (IFBL D7.41), ruines de l’église, 26.07.1948, Fr. Macédone s.n. (BR);

Luxembourg: Orval, bord de chemin, 15.10.1985, B. Bastin s.n. (BR);

Oost-Vlaanderen: Waasmunster (IFBL C4.51), Roodebosch (Uilenkasteel), 21.07.1903, Deguns s.n. (BR);

Namur: Falaën (IFBL H5.35), au pied du mur de cloture de la propriété Boël, 16.06.1925, E. Michel s.n. (BR);

Vlaams-Brabant: Woluwe-St.-Pierre, près de Kapelleveld(?), tas de fumier, 10.06.1991, G. Bruynseels 1788 (BR); Woluwe-St.-Lambert, près du Campus Universitaire, site rudéralisé, tas de compost, 21.07.1991, G. Brunseels s.n. (BR);

West-Vlaanderen: Gits (IFBL D1.38.13), ruigte bij het station, 27.08.1987, F. Verloove 3 (BR).

Leonurus cardiaca subsp. villosus, Lommel ('t Stort), former dump, September 2012, R. Barendse Leonurus cardiaca subsp. villosus, Lommel ('t Stort), former dump, September 2012, R. Barendse

The exact residence status of Leonurus cardiaca subsp. villosus in Belgium (casual?, naturalized?) is uncertain but, at least in Genk, it survived for about 40 years. The last confirmed herbarium collection dates back to 1991 (Woluwe-Saint-Lambert) but it was recently reliably recorded by R. Barendse in Lommel (see: http://waarnemingen.be/waarneming/view/71102641). Belgian botanists are encouraged to look out for this taxon in order to assess its current status and distribution in Belgium. In parts of Germany Leonurus cardiaca subsp. villosus seems to be the prevailing taxon these days. According to Jäger & Werner (2005) it is the “usual” beekeepers plant (not L. cardiac s.str.). See also Ludwig (1987), Melzer (1997), etc.

For convenience, both taxa are opposed in the following couplet and some photos of both are presented.

  • Stem with dense, patent hairs (ca. 1-2 mm long) on faces and angles (but often glabrescent with age!). Lower cauline leaves always divided more than ½ to base, densely hairy on both surfaces. Calyx densely hairy (with numerous patent hairs) === subsp. villosus
  • Stem with scattered, adpressed hairs (ca. 0.5 mm long) on angles only. Lower cauline leaves often divided less than ½ to base, nearly glabrous on upper surface. Calyx glabrous or sparsely adpressed hairy === subsp. cardiaca

Finally a word about the taxonomy and nomenclature of this taxon. If it were accepted as a “good” species than it should be either called Leonurus quinquelobatus or L. villosus (see Holub 1993 for a thorough discussion on the subject that is behind the scope of the present note). The taxonomic rank of this taxon is rather controversial: it is given species rank by Russian authors (known to apply a narrow species concept; see Kupryanova 1977) but also, for instance, by Euro+Med Plantbase (that subsumes Leonurus canescens and L. intermedius under L. cardiaca s.str.). On the other hand, in the modern Czech flora (Tomšovic 2000; usually also handling a rather narrow species concept) it is merely included in Leonurus cardiaca (which is surprisingly in disaccord with Holub, another Czech author and familiar with this taxon). The “truth” may be somewhere in between: Jäger & Werner (2005), for instance, apply subspecies rank and this seems, indeed, most appropriate.

Leonurus cardiaca subsp. villosus, Lommel ('t Stort), former dump, September 2012, R. Barendse Leonurus cardiaca subsp. villosus, Lommel ('t Stort), former dump, September 2012, R. Barendse



References

Durand T. (1899) Phanérogames. In: De Wildeman E. & Durand T., Prodrome de la flore belge. A. Castaigne Editeur, Bruxelles: 1112 p.

Holub J. (1993) Leonurus intermedius, sepcies nova - with additional notes on some other Leonurus taxa. Preslia 65: 97-115.

Jäger E.J. & Werner K. (eds.) (2005) Rothmaler Band 4. Exkursionsflora von Deutschland. Gefässpflanzen: Kritischer Band. Springer Verlag, Berlin: 880 p.

Kupryanova L.A. (1977) Leonurus. In: Shishkin B.K. (ed.), Flora of the U.S.S.R., vol. XXI. Academic Scienc. U.S.S.R.: 105-114.

Lambinon J., Delvosalle L., Duvigneaud J. (avec coll. Geerinck D., Lebeau J., Schumacker R. & Vannerom H.) (2004) Nouvelle Flore de la Belgique, du Grand-Duché de Luxembourg, du Nord de la France et des Régions voisines (Ptéridophytes et Spermatophytes). Cinquième édition. Jardin botanique national de Belgique, Meise: CXXX + 1167 p.

Loos G.H. (1995) Bestimmungsschlüssel für die Leonurus cardiaca-Gruppe in Deutschland. Floristische Rundbriefe 29(1): 30-33.

Ludwig W. (1987): Über die „Dorfpflanze" Leonurus cardiaca L. s. lat. (Lamiaceae) und ihre Vorkommen in Hessen. Jahresber. Wetterauischen Ges. Gesammte Naturk. 137-139: 17–29.

Melzer H. (1997) Neues zur Flora von Steiermark, XXXVI. Mitt. naturwiss. Ver. Steiermark 127: 65-75.

Tomšovic P. (2000) Leonurus. In: Slavík B. (ed.), Kvetena CR 6. Academia, Praha: 609-610.

Van Landuyt W. (2006) Leonurus cardiaca. 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: 534.

Verloove F. (2006) Catalogue of neophytes in Belgium (1800-2005). Scripta Botanica Belgica 39: 89 p.

Filip Verloove, September 2012

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