Helichrysum

Helichrysum Mill.

As usually understood (e.g. Mabberley 2008) Helichrysum is a very heteromorphous genus of ca. 500-600 species (Galbany-Casals & al., div. publ.). It is originally confined to the Old World and its center of diversity possibly is in South Africa. Its generic boundaries have considerably changed in the past decades. Several species (including those from Australia) are now accommodated in segregate genera (for instance Xerochrysum to which the popular annual strawflower X. bracteatum (Vent.) Tzvelev now belongs). On the other hand, molecular data have shown that related genera like Anaphalis and Laphangium (the latter with the native species L. luteoalbum (L.) Tzvelev; syn.: Gnaphalium luteoalbum L.) are best united with it (Galbany-Casals & al. 2014, Nie & al. 2016).

One species, Helichrysum arenarium (L.) Moench, is a very rare and local, nearly extinct native in Belgium (Lambinon & al. 2004). Several species of Helichrysum are cultivated as ornamentals (see Brown 2000 and Jäger & al. 2008 for recent accounts for Europe).

1. Leaves almost circular with a distinct petiole. Flower heads creamy-white. Stem eventually trailing === Helichrysum petiolare

1. Leaves narrowly linear without distinct petiole. Flower heads yellow. Stem never trailing === 2

2. Aromatic (strong smell of curry), shrubby perennial (becoming woody at base). Involucre 2-4 mm across. Leaves usually greenish, glabrescent and only sparsely tomentose when young === H. italicum

2. Inodorous, herbaceous perennial. Involucre 4-5 mm across. Leaves usually densely white-tomentose (native) === H. arenarium

Literature:

Brown N. (2000) Helichrysum. In: Cullen J. & al. (eds.), The European Garden Flora, vol. 6. Cambridge University Press, Cambridge: 560-562.

Clapham A.R. (1976) Helichrysum. In: Tutin T.G. & al. (eds.), Flora Europaea, vol. 4. Cambridge University Press, Cambridge: 128-131.

Galbany-Casals M., Unwin M., Garcia-Jacas N., Smissen R.D., Susanna A. & Bayer R.J. (2014) Phylogenetic relationships in Helichrysum (Compositae: Gnaphalieae) and related genera: Incongruence implications for generic delimitation. Taxon 63: 608–624. [available online at: http://digital.csic.es/bitstream/10261/110003/3/phylogenetic-relationshi...

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.

Mabberley D.J. (2008) Mabberley’s plant-book (3th ed.). Cambridge University Press, Cambridge: XVIII + 1021 p.

Nie Z. L., Funk V. A., Meng Y., Deng T., Sun H. & Wen J. (2016) Recent assembly of the global herbaceous flora: evidence from the paper daisies (Asteraceae: Gnaphalieae). New Phytol. 209: 1795–1806. [available online at: https://nph.onlinelibrary.wiley.com/doi/epdf/10.1111/nph.13740]