Crepis is a genus of ca. 200 species, mostly native to the northern hemisphere (with few additional species in South America and South Africa) (Mabberley 2008). Its generic limits have long been somewhat obscure and several segregates have been recognized in the past (viz. Barkhausia Moench and Lagoseris Bieb). However, all are better included in a broadly circumscribed genus Crepis (see also Babcock 1947) which also is in accordance with recent molecular phylogenetic studies (Enke 2009). These studies have shown that Crepis is paraphyletic and comprises three well supported clades. One accommodates Crepis s.str. but a second clade includes, among others, morphologically rather distinct genera like Lapsana and Rhagadiolus. According to Enke l.c. both should, at least for the time being, be maintained in their current generic circumscription. Crepis is furthermore closely related to Hieracium. Several species are doubtlessly or probably native in Belgium: Crepis biennis L., C. capillaris (L.) Wallr., C. foetida L. subsp. foetida, C. paludosa (L.) Moench and C. polymorpha Pourr. (Lambinon & al. 2004). An additional species, Crepis praemorsa (L.) F.W. Walther, is native close to the Belgian frontiers but was not yet recorded with certainty from Belgium, until recently when it was recorded in a heathland in Elsenborn in 2010 (Frankard & Dahmen 2013).
Crepis nicaeensis Balb. was formerly well-established as a weed of calcareous arable land around Rochefort and Jemelle, at least between 1860 and 1908.
Mature achenes are required for the correct identification of members of the genus Crepis. The beak on the achene is much less obvious before maturity.
Additional information on the taxonomy of Crepis (and Cichorieae as a whole) is provided by The International Cichorieae Network– a new initiative towards a web-distributed revision of the Cichorieae at: http://wp6-cichorieae.e-taxonomy.eu/portal/.
1 Receptacle with rigid hairs subtending the florets. Achenes strongly heteromorphous: the outer usually distinctly winged, the inner fusiform. Annual, all or most leaves basal === Crepis sancta
Receptacle glabrous or with ciliate pits, never with rigid hairs subtending the flowers. Achenes not or only slightly heteromorphous, the outer never distinctly winged. Perennial, biennial or annual (in the latter case never with all leaves basal) === 2
2 At least inner mature achenes contracted into a distinct beak === 3
Mature achenes at most attenuate at apex, not distinctly beaked === 6
3 Involucre and pedicels covered by rigid yellowish bristle-like hairs === C. setosa
Involucre and pedicels without rigid bristle-like hairs === 4
4 Stem leaves absent or minute, rosette leaves runcinate. Achenes with beak much longer than body === C. bursifolia
Stem leafy, rosette leaves not runcinate. Achenes with shorter beak === 5
5 Inner achenes with a long slender beak, outer achenes less distinctly beaked. Heads drooping before anthesis. Styles yellow. Plant with a very strong, foetid odour when fresh === C. foetida (incl. subsp. rhoeadifolia)
Achenes all alike. Heads erect before anthesis. Styles usually greenish. Plant odourless (native) === C. polymorpha
6 Rhizomatous perennial. Pappus yellowish white (native) === C. paludosa
Annual or biennial. Pappus white === 7
7 Involucre perfectly glabrous with strongly keeled phyllaries. Stem and leaves at least in part glandular pubescent === C. pulchra
Involucre at least slightly glandular or eglandular pubescent, without keeled phyllaries. Stem and leaves never glandular === 8
8 Involucral bracts glabrous on the inner side (native) === C. capillaris
Involucral bracts appressed hairy on the inner side === 9
9 Achene 10-ribbed, dark brown at maturity, 2,5-4 mm long. Annual === C. tectorum
Achenes usually 13-ribbed (rarely 10-20), yellowish, 5-13 mm long. Biennial (native) === C. biennis
Additional alien: Crepis nicaeensis Balb. (syn.: Barkhausia nicaeensis (Balb.) Link) (W- and C-Medit., agricult. weed).
Babcock E.B. (1947) The genus Crepis. Univ. Calif. Publ. Bot. 21: 1-197, 22: 198-1030.
Bogler D.J. (2006) Crepis. In: Flora of North America Editorial Committee (eds.), Flora of North America, vol. 19. Oxford University Press, New York-Oxford: 222-239. [available online at: http://www.efloras.org/florataxon.aspx?flora_id=1&taxon_id=108351]
Enke N. (2008) Phylogeny and Character Evolution in the Genus Crepis L. (Cichorieae, Compositae). PhD thesis Universität Berlin-Dahlem: 137 p. [available online at: http://www.diss.fu-berlin.de/diss/receive/FUDISS_thesis_000000009361]
Enke N. (2009) Contributions towards a revised infrageneric classification of Crepis (Cichorieae, Compositae). Willdenowia 39(2): 229-245.
Frankard P. & Dahmen R. (2013) Une espèce nouvelle pour la flore belge: Crepis praemorsa (L.) F.W. Walther, sur le plateau d'Elsenborn (Haute Ardenne). Natura Mosana 66(4): 69-76.
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