Helianthus petiolaris

5. Helianthus petiolaris Nutt. (syn.: H. patens Nutt., H. integrifolius Nutt.) (N-Am.) – A very rare and ephemeral alien. Recorded on wasteland in the port of Antwerpen in 1949 (and published as Sanvitalia procumbens; see Delvosalle 1953). A more recent record (Verloove & Vandenberghe 1997), also in the port of Antwerpen, finally turned out to be in error for Helianthus annuus (Verloove & Lambinon 2008).

Helianthus petiolaris often much resembles H. annuus and only flowering plants can be named with confidence. Receptacular scales (at least the central ones) have a conspicuous tuft of long, white hairs at the apex. Helianthus petiolaris is furthermore said to have leaves that are more tappered at base and involucral bracts that are gradually narrowed at apex but these characters proved to be unreliable. In many European countries Helianthus petiolaris is a rather typical soybean alien (see Verloove & Vandenberghe 1997 for an overview).

Helianthus aridus Rydb., given as a synonym by Sell & Murrell (2006), is in fact a synonym of H. annuus according to Schilling (2006).

Selected literature:

Delvosalle L. (1953) Quelques adventices nouvelles pour la Belgique. Bull. Soc. Roy. Bot. Belg. 85: 297-303.

Schilling E.E. (2006) Helianthus. In: Flora of North America Editorial Committee (eds.), Flora of North America, vol. 21. Oxford University Press, New York-Oxford: 141-169.

Sell P. & Murrell G. (2006) Flora of Great Britain and Ireland. Vol. 4 Campanulaceae – Asteraceae. Cambridge University Press, Cambridge: XXVIII + 624 p.

Verloove F. & Lambinon J. (2008) Neophytes in Belgium: corrections and adjustments. Syst. Geogr. Pl. 78: 63-79.

Verloove F. & Vandenberghe C. (1997) Nieuwe en interessante voederadventieven in België en aangrenzend Nederland, hoofdzakelijk in 1996. Dumortiera 68: 13-26.

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