Primulaceae
(incl. Myrsinaceae)
The circumscription of Primulaceae is still uncertain and remains controversial. Molecular phylogenetic research advocated the transfer of many genera that were traditionally placed in Primulaceae to Myrsinaceae (e.g. Källersjö & al. 2000). For the Belgian flora the following genera are concerned: Anagallis, Cyclamen, Glaux, Lysimachia and Trientalis. Samolus, in turn, was transferred to Theophrastaceae. However, both these families are now accommodated in a broadly circumscribed Primulaceae family that, this way, is monophyletic (APGIII 2009); this classification is applied here as well, mainly for practical reasons (i.e., western European Primulaceae being morphologically very different compared with the tropical Myrsinaceae and Theophrastaceae; see also Stace 2010a, Jäger & al. 2014, Tison & de Foucault 2014).
At the generic level similar difficulties have been encountered, also as a result of recent molecular studies. Hao & al. (2004) already showed that Glaux is deeply nested within Lysimachia. More numerous data sets used by Anderberg & al. (2007) confirmed this and demonstrated that, among others, Anagallis (incl. Centunculus) and Trientalis are also completely nested in Lysimachia. Manns & Anderberg (2009) made the corresponding nomenclatural transfers. Despite being morphologically fairly aberrant, this new generic concept has since then being applied by most authors (e.g. Banfi & Galasso 2005, Tison & de Foucault 2014; see however Stace 2010b, who classified the amalgamation of Anagallis and Lysimachia as an “unwelcome newcomer”).
In this account the application of an enlarged circumscription of Lysimachia seems inevitable. Alternatively, splitting-up Lysimachia could be envisaged, separating the Belgian representatives in three genera (L. nummularia and L. punctata, vs. L. nemorum, vs. L. thyrsiflora and L. vulgaris). Similarly, Anagallis should then be further split in two genera, one including A. arvensis, the other A. minima (syn.: Centunculus minimus) and A. tenella.
1 Leaves pinnate with linear lobes. Plant with submerged vegetative parts (native) === Hottonia
Leaves simple. Vegetative parts not submerged === 2
2 All leaves basal === 3
Leaves alternate, opposite or whorled, never all basal === 5
3 Slender annual. Calyx accrescent at maturity. Corolla minute, shorter than the calyx, white or pink === Androsace
Perennial herbs. Calyx not accrescent at maturity. Corolla showy, distinctly longer than calyx, variably colored === 4
4 Corolla lobes strongly reflexed. Plant with subterranean tubers. Fruiting pedicel spiraled === Cyclamen
Corolla lobes patent to erect, never reflexed. Plant without tubers. Fruiting pedicel straight === Primula
5 Ovary semi-inferior (native) === Samolus
Ovary superior === Lysimachia (incl. Anagallis, Centunculus, Glaux, Trientalis)
References:
Anderberg A.A., Manns U. & Källersjö M. (2007) Phylogeny and floral evolution of the Lysimachieae (Ericales, Myrsinaceae): evidence from ndhF sequence data. Willdenowia 37: 407-421. [available online at: http://botanischer-garten-berlin.org/sites/alienplantsbelgium.bedefault/files/documents/wi37-2Anderberg%2Bal.pdf]
APG III (2009) An update of the Angiosperm Phylogeny Group classification for the orders and families of flowering plants. APG III. Bot. J. Linn. Soc. 161(2): 105-121. [available online at: http://onlinelibrary.wiley.com/doi/10.1111/j.1095-8339.2009.00996.x/pdf]
Banfi E. & Galasso G. (2005) Notes on systematics and taxonomy for the Italian vascular flora. 1. Atti Soc. it. Sci. nat. Museo civ. Stor. nat. Milano, 146 (II): 219-244. [available online at: https://www.researchgate.net/publication/270577694_Notes_on_systematics_and_taxonomy_for_the_Italian_vascular_flora._1]
Hao G., Yuan Y.M., Hu C.M., Ge X.J. & Zhao N.X. (2004) Molecular phylogeny of Lysimachia (Myrsinaceae) based on chloroplast trnL-F and nuclear ribosomal ITS sequences. Mol. Phylogenet. Evol. 31(1): 323-339.
Hu C.M. & Kelso S. (1996) Primulaceae. In: Wu Z.Y. & Raven P.H. (eds.), Flora of China, vol. 15. Science Press, Beijing & Missouri Botanical Garden Press, St. Louis: 99-185. [available online at: http://flora.huh.harvard.edu/china/mss/volume15/Primulaceae.published.pdf]
Jäger E.J., Ebel F., Fritsch R., Hanelt P. & Pistrick K. (2014) Kommentare, Korrekturen und Nachträge zum 5. Band (Krautige Zier- und Nutzpflanzen) der Rothmaler-Exkursionsflora. Schlechtendalia 27: 41-60. [available online at: http://public.bibliothek.uni-halle.de/index.php/schlechtendalia/article/view/1185]
Källersjö M., Bergqvist G. & Anderberg A.A. (2000) Generic Realignment in Primuloid Families of the Ericales S.L.: A Phylogenetic Analysis Based on DNA Sequences from Three Chloroplast Genes and Morphology. American Journal of Botany 87(9): 1325-1341. [available online at: http://www.amjbot.org/content/87/9/1325.full.pdf+html]
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.
Manns U. & Anderberg A.A. (2009) New combinations and names in Lysimachia (Myrsinaceae) for species of Anagallis, Pelletiera and Trientalis. Willdenowia 39(1): 49-54. [available online at: http://www.bioone.org/doi/pdf/10.3372/wi.39.39103]
Pax F. & Knuth R. (1905) Primulaceae. In: Engler A. (ed.), Das Pflanzenreich 22. [available online at: http://www.biodiversitylibrary.org/item/71654#page/5/mode/1up]
Stace C. (2010a) New flora of the British Isles, 3th ed.: XXXII + 1232 p. Cambridge University Press.
Stace C.A. (2010b) Classification by molecules : What’s in it for field botanists ? Watsonia 28(2): 103-122. [available online at: http://archive.bsbi.org.uk/Wats28p103.pdf]
Tison J.-M. & de Foucault B. (coord.) 2014) Flora Gallica. Flore de France. Editions Biotope, Mèze : xx + 1196 p.