Typha is a nearly cosmopolitan genus of ca. 10-12 species. Two species are native in Belgium: Typha angustifolia L. and T. latifolia L. Their sterile hybrid (Typha xglauca Godr.) rarely occurs as well. In addition to these native species some others are increasingly cultivated as ornamentals for pond and lake margins (see Jäger et al. 2008 for an up-to-date account of the genus in cultivation in Central-Europe). Some of these species are rather reminiscent of both native species and might have been overlooked so far (especially Typha shuttleworthii W.D.J. Koch et Sond.; syn.: T. latifolia subsp. shuttleworthii (W.D.J. Koch et Sond.) Stoj. et Stef.). Fruits of Typha are easily wind-dispersed, often over long distances. Future occurrences of some of these ornamentals are therefore not unlikely.
Female flowers in Typha are either subtended by (filiform) hairs or by hairs and scales (i.e. hairs that are conspicuously flattened and enlarged towards apex). This is an important character but not always easily assessed. It is preferably noticed at maturity when flowers readily detach.
The phylogenetic relationships within the genus Typha were recently studied by Kim & Choi (2011).
1 Female flowers subtended by hairs as well as scales (the latter, at least most of them, as wide as or wider than stigmas) (native) === Typha angustifolia
1 Female flowers exclusively subtended by hairs or if scales are present these narrower than stigmas === 2
2 Female flowers subtended by hairs as well as scales. Sterile hybrids, often very tall (200 cm or more) === 3
2 Female flowers exclusively subtended by hairs. Fertile plants, rarely exceeding 200 cm === 4
3 Adaxial leaf surface and sheath with numerous mucilaginous (orangish) glands. Female spike at maturity pale brown === T. xprovincialis (T. domingensis x latifolia)
3 Mucilaginous glands absent from leaves and sheaths. Female spike medium to dark brown at maturity (native) === T. xglauca (T. angustifolia x latifolia)
4 Male and female part of inflorescence always distinctly separated (by 10-60 mm), the former at least twice as long as the latter. Leaves 2-4(-7) mm wide === T. laxmannii
4 Male and female part of inflorescence usually contiguous (more rarely separated by up to 25 mm), both parts about equal in length. Leaves 8-20 mm wide (native) === T. latifolia
Additional alien: Typha minima Funck (Eur., W-As., garden escape).
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Literature
Baryła J., Bróż E., Czylok A., Michalewska A., Nikel A., Nobis M., Piwowarczyk R., & Poloczek A. (2005) Typha laxmannii Lepech. the new, expansive kenophyte in Poland: distribution and taxonomy. Acta Soc. Bot. Pol. 74: 25-28 (available online at: http://www.botany.pl/pubs-pdf/Acta%20Societatis%20Botanicorum/2005/acta1_2005_025.pdf).
Cirujano S. (2008) Typha L. In: Castroviejo S. (ed.), Flora Iberica, vol. 18:, Real Jardín Botánico (CSIC), Madrid: 259-266.
Cook C.D.K. (1980) Typhaceae. In: Tutin T.G. & al. (eds.), Flora Europaea, vol. 5. Cambridge University Press, Cambridge: 275-276.
Galen Smith S. (2000) Typhaceae. In: Flora of North America Editorial Committee (eds.), Flora of North America, vol. 22. Oxford University Press, New York-Oxford: 278-285.
Graebner K. (1900) Typhaceae. In: Engler A. (ed.), Das Pflanzenreich 2(IV.8). Engelmann, Leipzig: 8-16. [available online at: http://www.biodiversitylibrary.org/item/68126#page/30/mode/1up]
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.
Jäger E.J. & Werner K. (eds.) (2005) Rothmaler Band 4. Exkursionsflora von Deutschland. Gefässpflanzen: Kritischer Band. Springer Verlag, Berlin: 880 p.
Jauzein P. (1990) Le genre Typha en Corse. Candollea 45: 314-334.
Kim C. & Choi H.-K. (2011) Molecular systematics and character evolution of Typha (Typhaceae) inferred from nuclear and plastid DNA sequence data. Taxon 60(5): 1417-1428.
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.
Nelson E.C. (1984) Typhaceae. In: Walters S.M. & al. (eds.), The European Garden Flora, vol. 1. Cambridge University Press, Cambridge: 113-114.
Van der Meijden R. (2005) Heukels’ Flora van Nederland (23e druk). Wolters-Noordhoff, Groningen: 685 p.
Vázquez Pardo F.M. (2012) Revisión del género Typha Tourn. ex L. (Typhaceae), en Extremadura (España). Folia Botanica Extremadurensis 6: 5-17. [available online at: https://jolube.files.wordpress.com/2012/07/folia_botanica_extremadurensi...