Achillea

Achillea L.

Achillea is a genus with ca. 115-130 species (Guo & al. 2004, Oberprieler & al. 2007), mainly native in the northern hemisphere. Its center of diversity is in southeastern Europe and southwestern Asia. Two species are native in Belgium: Achillea millefolium L. and A. ptarmica L. (Lambinon & Verloove 2012). A few additional species are cultivated as ornamentals (see Thornton-Wood 2000 & Jäger & al. 2008 for very useful overviews for Europe).
In addition to the alien species treated in this account Lambinon & al. (2004) cited two more species: Achillea crithmifolia Waldst. et Kit. and A. lanulosa Nutt. The citation of the former seems to be erroneous, the second species has only been found in Luxembourg (Grand Duchy), not in Belgium (Verloove & Lambinon 2008).
Some species of Achillea are exceedingly similar to those of Tanacetum (especially species of the latter genus with outer florets ligulate). However, in Tanacetum achenes usually have a small pappus (corona).
Molecular studies showed that with the inclusion of Otanthus and Leucocyclus, Achillea s.l. is a monophyletic assemblage and appears as sister to Anacyclus (Guo & al. 2004, Ehrendorfer & Guo 2005).
Achillea millefolium is morphologically variable and has been treated as either a single species with varieties or as multiple distinct species. It is clear that non-native taxa from this complex occur in Belgium, especially in newly sown roadsides, on coal mining spoil heaps, canal banks, etc. However, their identity should be critically assessed, preferably based on flow cytometry or molecular techniques. For the polyploid taxa many hybrid links and introgression from the diploids are suggested (Guo & al. 2012). Some plants have been ascribed to Achillea collina J. Becker ex Reichenb. [syn.: A. millefolium subsp. collina (J. Becker ex Reichenb.) Weiss], an allopolyploid (2n=36) (while native A. millefolium is a hexaploid with 2n=54), partly based on cytological studies on a population from a coal mining spoil heap in Eisden. This identity, however, was subsequently rejected (F. Ehrendorfer, in lit. 06.2009). Plants (often taller) with wider, flat leaves possibly belong to Achillea distans Waldst. et Kit. ex Willd., or at least may have some blood of it. The exact identity of plants with pinkish or reddish ligules (sometimes seen on dumps and in roadsides) also requires further study; these possibly also represent non-native taxa.
Very useful and up-to-date accounts for several taxa of the Achillea millefolium complex were published for Central Europe (Danihelka 2001, Danihelka 2003a, b, Danihelka & Rotreklová 2001a, b, Danihelka & Rotreklová 2002).

1 Ligules pure yellow on both sides === 2
Ligules usually white, very rarely pink or pale yellow === 3
2 Cauline leaves entire, serrate. Corymb 20-40 mm across === Achillea ageratum
Cauline leaves deeply pinnatisect. Corymb 40-100 mm across === A. filipendulina
3 Leaves simple, divided much less than ½ to midrib === 4
Leaves compound === 5
4 Leaves glandular punctate, up to 17 mm wide. Capitula 4-8 mm across. Ligules 7-8, ca. 3(-4) mm === A. cartilaginea
Leaves not glandular-punctate, up to 8 mm wide. Capitula 8-12 mm across. Ligules up to 13, ca. 5 mm (native) === A. ptarmica
5 Middle cauline leaves rounded to ovate in outline, 1,5-3x as long as wide, plane. Plant without stolons === A. nobilis
Middle cauline leaves lanceolate to linear in outline, 3-15x as long as wide, terete. Plant (shortly) stoloniferous (native) === A. millefolium s.l.

Additional alien: Achillea setacea Waldst. et Kit. [syn.: A. millefolium subsp. setacea (Waldst. et Kit.) Čelak., A. millefolium var. setacea (Waldst. et Kit.) W.D.J. Koch] (S, SE and SC-Eur., grain alien?).

Literature:


Dąbrowska J. (1982) Systematic and geographic studies of the genus Achillea L. in Poland with special reference to Silesia. Acta Univ. Wratislav. Pr. Bot. 24: 1-223.
Danihelka J. (2001) Achillea setacea in the Czech Republic, with taxonomic remarks. Preslia 73: 97-120. [available online at: https://www.researchgate.net/publication/264423426_Achillea_setacea_in_t...
Danihelka J. (2003a): Achillea asplenifolia in Moravia (Czech Republic), with taxonomic remarks. Preslia 75: 115-135. [available online at: http://www.preslia.cz/P032CDan.pdf]
Danihelka J. (2003b) Achillea pannonica in the Czech Republic, with taxonomic remarks. Preslia 73: 213-244. [available online at: https://www.researchgate.net/publication/264423457_Achillea_pannonica_in...
Danihelka J. & Rotreklová O. (2001a) Achillea pratensis – a recently recognized species of the Czech flora. Preslia 73: 1–27. [available online at: https://www.researchgate.net/publication/271307100_Achillea_pratensis_-_...
Danihelka J. & Rotreklová O. (2001b) Chromosome numbers within the Achillea millefolium and the A. distans groups in the Czech Republic and Slovakia. Folia Geobot. 36: 163–191. [available online at: https://www.researchgate.net/publication/257181467_Chromosome_numbers_wi...
Danihelka J. & Rotreklová O. (2002) Achillea distans (Asteraceae) confirmed as native in the Bieszczady Mts (SE Poland). Fragmenta Floristica et Geobotanica 45: 257-263.
Danihelka J., Saukel J. & Ehrendorfer F. (2006) Typification of the names Achillea millefolium var. collina and A. pannonica (Asteraceae, Anthemideae). Taxon 55: 507-510. [available online at: https://www.researchgate.net/publication/233648924_Typification_of_the_n...
Ehrendorfer F. & Guo Y.P. (2005) Changes in the circumscription of the genus Achillea (Compositae-Anthemideae) and its subdivision. Willdenowia 35: 49-54. [available online at: http://www.bioone.org/doi/pdf/10.3372/wi.35.35102]
Ehrendorfer F. & Guo Y.-P. (2006) Multidisciplinary studies on Achillea sensu lato (Compositae-Anthemideae): new data on systematics and phylogeography. Willdenowia 36: 69-87. [available online at: http://www.bioone.org/doi/pdf/10.3372/wi.36.36105]
Guo Y.-P., Ehrendorfer F. & Samuel R. (2004) Phylogeny and systematics of Achillea (Asteraceae-Anthemideae) inferred from nrITS and plastid trnL-F DNA sequences. Taxon 53(3): 657-672. [available online at: https://www.researchgate.net/profile/Yanping_Guo2/publication/270156356_...
Guo Y.-P., Wang S.-Z., Vogl C. & Ehrendorfer F. (2012) Nuclear and plastid haplotypes suggest rapid diploid and polyploid speciation in the N Hemisphere Achillea millefolium complex (Asteraceae). BMC Evolutionary Biology 2012 12:2. DOI: 10.1186/1471-2148-12-2 [available online at: http://bmcevolbiol.biomedcentral.com/articles/10.1186/1471-2148-12-2]
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., 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.
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.
Oberprieler C., Himmelreich S. & Vogt R. (2007) A new subtribal classification of the tribe Anthemideae (Compositae). Willdenowia 37: 89-114. [available online at: https://www.bgbm.org/sites/default/files/documents/wi37-1Oberprieler%2Ba...
Richardson I.B.K. (1976) Achillea. In: Tutin T.G. & al. (eds.), Flora Europaea, vol. 4. Cambridge University Press, Cambridge: 159-165.
Saukel J., Anchev M., Guo Y.P., Vitkova A., Nedelcheva A., Goranova V., Konakchiev A., Lambrou M., Nejati S., Rauchensteiner F. & Ehrendorfer F. (2003) Comments on the biosystematics of Achillea (Asteraceae-Anthemideae) in Bulgaria. Phytologia Balcanica 9: 361-400.
Saukel J. & Länger R. (1992a) Die Achillea millefolium-Gruppe (Asteraceae) in Mitteleuropa. Phyton 31: 185-207. [available online at: http://www.zobodat.at/pdf/PHY_31_2_0185-0207.pdf]
Saukel J. & Länger R. (1992b) Die Achillea millefolium-Gruppe (Asteraceae) in Mitteleuropa. Phyton 32: 47-78. [available online at: http://www.zobodat.at/pdf/PHY_32_1_0047-0078.pdf]
Sell P. & Murrell G. (2006) Flora of Great Britain and Ireland. Vol. 4 Campanulaceae – Asteraceae. Cambridge University Press, Cambridge: XXVIII + 624 p.
Thornton-Wood S.P. (2000) Achillea. In: Cullen J. & al. (eds.), The European Garden Flora, vol. 6. Cambridge University Press, Cambridge: 607-612.
Tison J.-M. & de Foucault B. (coord.) 2014) Flora Gallica. Flore de France. Editions Biotope, Mèze : xx + 1196 p.
Trock D.K. (2006) Achillea. In: Flora of North America Editorial Committee (eds.), Flora of North America, vol. 19. Oxford University Press, New York-Oxford: 492-494. [available online at: http://www.efloras.org/florataxon.aspx?flora_id=1&taxon_id=100191]
Verloove F. & Lambinon J. (2008) Neophytes in Belgium: corrections and adjustments. Syst. Geogr. Pl. 78: 63-79.
Wagenitz G. (1979) Achillea. In: Hegi G. (ed.), Illustrierte Flora van Mitteleuropa, vol. 6(3) (2nd ed.). Carl Hanser Verlag, München: 310-349.

Taxonomic name: 
Scratchpads developed and conceived by (alphabetical): Ed Baker, Katherine Bouton Alice Heaton Dimitris Koureas, Laurence Livermore, Dave Roberts, Simon Rycroft, Ben Scott, Vince Smith