Cynoglossum L.
Cynoglossum is, in its traditional circumscription, a cosmopolitan genus with ca. 55-75 species. Two centers of diversity are discernible, one in Asia and another in the Mediterranean region. Two species, C. germanicum Jacq. and C. officinale L., are native in Belgium (Lambinon & Verloove 2012).
The genus, however, is extremely complex in terms of taxonomy. Species delimitation is often critical and also the generic limits of Cynoglossum remain unclear. Recent phylogenetic evidence suggests that Cynoglossum is not monophyletic and relationships among members of the genus remain uncertain (Cohen 2011, Cohen 2014). Especially American and African members of Cynoglossum probably belong in separate genera. Pending additional studies, the genus is here accepted in its traditional sense.
In addition to the two native species, a third species from Asia has recently been recorded as alien in Belgium.
1 Corolla sky blue (rarely white or pink in cultivars), rarely exceeding 5 mm across. Nutlets ca. 3 mm across === Cynoglossum amabile
Corolla reddish-purple (native), always larger (ca. 6-10 mm across). Nutlets ca. 5-8 mm across === C. germanicum and C. officinale
Additional alien: Cynoglossum clandestinum Desf. (W-Medit., wool alien).
Literature:
Brand A. (1921) Borraginaceae-Borraginoideae, Cynoglosseae. In: Engler, A. (Ed.) Das Pflanzenreich: regni vegetablilis conspectus. W.Engelmann, Leipzig: 183 pp. [available online at: http://www.biodiversitylibrary.org/item/61955#page/5/mode/1up]
Cohen J.I. (2011) A phylogenetic analysis of morphological and molecular characters of Lithospermum L. (Boraginaceae) and related taxa: Evolutionary relationships and character evolution. Cladistics 27: 559-580.
Cohen J.I. (2014) A phylogenetic analysis of morphological and molecular characters of Boraginaceae: Evolutionary relationships, taxonomy, and patterns of character evolution. Cladistics 30: 139-169. [available online at: http://www.sci.sdsu.edu/plants/cryptantha/pdfs/Cohen2013-Boraginaceae.pdf]
Ge-Ling Z., Riedl H. & Kamelin R. (1995) Boraginaceae. In: Wu Z.Y. & Raven P.H. (Eds.), Flora of China, Vol 16. Science Press, Bejing, pp. 329-431. [available online at: http://www.efloras.org/florataxon.aspx?flora_id=2&taxon_id=10115]
Hilger H., Greuter W. & Stier V. (2015) Taxa and names in Cynoglossum sensu lato (Boraginaceae, Cynoglosseae): an annotated, synonymic inventory, with links to the protologues and mention of original material. Biodiversity Data Journal 3: e4831. [available online at: https://www.researchgate.net/publication/275895201_Taxa_and_names_in_Cyn...
König J., Siwakoti M., Hilger H.H. & Weigend M. (2015) A revision of the genus Cynoglossum L. (Boraginaceae Juss.) in Nepal and notes on the widespread Asian species. Phytotaxa 224(1): 1-28. [available online at: http://webcache.googleusercontent.com/search?q=cache:u5_lzXFoF2cJ:journa...
Lambinon J. & Verloove F. (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.
Miller J.S. (2005) A synopsis of the genus Cynoglossum L. (Boraginaceae) in Madagascar and the Comoro Islands. Adansonia 27: 113-127. [available online at: http://sciencepress.mnhn.fr/sites/alienplantsbelgium.bedefault/files/art...
Popov M.G. (1953) Boraginaceae. In: Shishkin B.K. & Bobrov E. (Eds.), Flora URSS: Tubiflorae. Izdatel’stvo Akademii Nauk SSSR., Leningrad, Moscow, pp. 97–691, 703–718. [available online at: http://www.biodiversitylibrary.org/item/95084#page/1/mode/1up]
Selvi F., Coppi A. & Cecchi L. (2011) High epizoochorous specialization and low DNA sequence divergence in Mediterranean Cynoglossum (Boraginaceae): Evidence from fruit traits and ITS region. Taxon 60(4): 969‑985. [available online at: https://www.researchgate.net/publication/233499967_High_epizoochorous_sp...
Weigend M., Luebert F., Selvi F., Brokamp G. & Hilger H.H.H. (2013) Multiple origins for Hound’s tongues (Cynoglossum L.) and Navelseeds (Omphalodes Mill.) – The phylogeny of the borage family (Boraginaceae s.str.). Molecular Phylogenetics and Evolution 68: 604-618. [available online at: http://repositorio.uchile.cl/bitstream/handle/2250/120379/Multiple%20ori...
Weigend M., Selvi F., Gottschling M. & Hilger H.H. (2009) Marbleseeds are Gromwells—systematics and evolution of Lithospermum L. s.l. (Boraginaceae tribe Lithospermeae) based on molecular and morphological data. Molecular Phylogenetics and Evolution 52: 755–768. [available online at: https://www.researchgate.net/publication/26236011_Marbleseeds_are_gromwe...