Stachys L.
(incl. Betonica L.)
Stachys is a large, widely distributed genus in the temperate regions of the world (some species on mountains in the tropics). Its generic limits are still very unclear and a conservative generic concept is applied here. For instance, Betonica is here included in Stachys (following Mabberley 2008) although many authors accept it as a separate genus and molecular data confirm that it is not closely related to the remainder of the genus (Lindqvist & Albert 2002). Molecular phylogenetic studies have also shown that several genera, including Sideritis, are in fact embedded within Stachys (Lindqvist & Albert l.c.). In its current circumscription Stachys is a genus of ca. 300-450 species. Eight species are native in Belgium: Stachys alpina L., S. annua (L.) L., S. arvensis (L.) L., S. germanica L., S. officinalis (L.) Trev. (syn.: Betonica officinalis L.), S. palustris L., S. recta L. and S. sylvatica L. (Lambinon & Verloove 2012). The annual weedy species Stachys annua and S. arvensis are decreasing in their native habitats but they are sometimes seen as grain aliens or as container weeds in plant nurseries. Several species of Stachys (incl. some of the native ones) are cultivated as ornamentals. Especially the Stachys germanica group (with, among others, S. alpina, S. byzantina, S. cretica and S. germanica) is taxonomically very complex and in need of revision (Ball 1972).
1 Corolla yellowish (native) === Stachys annua and S. recta
Corolla reddish, purplish or pinkish (rarely white) === 2
2 Leaves mostly basal, with 1-3 pair of cauline leaves. Flowers sessile (subgenus Betonica) === 3
Stem with more than 3 pair of leaves. Flowers stalked, at least shortly (subgenus Stachys) === 4
3 Corolla 12-18 mm long. Nutlets 2.5 x 0.7 mm or smaller. Basal leaves narrowly ovate-oblong (native) === S. officinalis
Corolla 30-35 mm long. Nutlets 3.5-4 x 2.5-3 mm. Basal leaves broadly ovate to triangular === S. macrantha
4 Annual (native) === S. arvensis
Perennial === 5
5 Bracteoles absent or minute, at most ¼ of calyx length. Upper lip of corolla hairless or sparsely short hairy (native) === Stachys palustris and S. sylvatica
Bracteoles at least as long as calyx. Upper lip of corolla densely silky-hairy === 6
6 Upper part of stem with long patent eglandular hairs intermixed with short glandular hairs. Leaves coarsely serrate, cordate at base (native) === S. alpina
Stem eglandular. Leaves cuneate to cordate at base === 7
7 Entire plant densely white-woolly, hairs completely obscuring the leaf surfaces. Leaves cuneate at base, subentire === Stachys byzantina
Plant more greyish-woolly, hairs not completely obscuring the upper leaf surface. At least lowermost leaves cordate at base (native) === S. germanica
Additional aliens: Stachys atherocalyx K. Koch (SE-Eur., vector unknown) and S. cretica L. subsp. salviifolia (Ten.) Rech.f. (syn.: S. salviifolia Ten., S. germanica subsp. salviifolia (Ten.) Gams) (C-Medit., garden escape).
Literature:
Ball P.W. (1972) Stachys. In: Tutin T.G. & al. (eds.), Flora Europaea, vol. 3. Cambridge University Press, Cambridge: 151-157.
Bhattacharjee R. (1980) Taxonomic studies in Stachys L. II: A new infrageneric classification of Stachys L. Notes Roy. Bot. Gard. Edinburgh 38: 65-96.
Cullen J. (2000) Stachys. In: Cullen J. & al. (eds.), The European Garden Flora, vol. 6. Cambridge University Press, Cambridge: 199-203.
Jäger E.J. & Werner K. (eds.) (2005) Rothmaler Band 4. Exkursionsflora von Deutschland. Gefässpflanzen: Kritischer Band. Springer Verlag, Berlin: 880 p.
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.
Lindqvist C. & Albert V.A. (2002) Origin of the Hawaiian endemic mints within North American Stachys (Lamiaceae). American Journal of Botany 89(10): 1709-1724. [available online at: http://www.amjbot.org/content/89/10/1709.full.pdf+html]
Mabberley D.J. (2008) Mabberley’s plant-book (3th ed.). Cambridge University Press, Cambridge: XVIII + 1021 p.
Mulligan G.A. & Munro D.B. (1989) Taxonomy of species of North American Stachys (Labiatae) found north of Mexico. Naturaliste Canad. 116: 35-51.
Nelson J.B. (1981) Stachys (Labiatae) in southeastern United States. Sida 9: 104-123.
Salmaki Y., Zarre S., Ryding P.O., Lindqvist C., Bräuchler C., Heubl G., ... Bendiksby M. (2013). Molecular phylogeny of Stachydeae (Lamiaceae sybfamily Lamioideae). Molecular Phylogenetics and Evolution 69: 535-551.
Sell P. & Murrell G. (2009) Flora of Great Britain and Ireland. Vol. 3 Mimosaceae – Lentibulariaceae. Cambridge University Press, Cambridge: XXVIII + 595 p.