Helianthus tuberosus and H. x laetiflorus

Often users take for granted that all perennial sunflowers are to be identified as Helianthus tuberosus. Actually many, if not most, observations depict Helianthus x laetiflorus.
Here some works on the two taxa:
https://www.biodiversitylibrary.org/item/14536#page/129/mode/1up
http://www.efloras.org/florataxon.aspx?flora_id=1&taxon_id=114871
https://www.researchgate.net/profile/Lajos_Balogh4/publication/296815285_Sunflower_species_Helianthus_spp/links/56dabfbd08aee73df6d2ab23/Sunflower-species-Helianthus-spp.pdf
https://www.degruyter.com/downloadpdf/j/botlit.2014.20.issue-2/botlit-2014-0018/botlit-2014-0018.pdf

Posted on 06 de outubro de 2019, 08:43 AM by blue_celery blue_celery

Comentários

All this are good. But how to distinguish the wild forms of Helianthus tuberosus from H. x laetiflorus? Is it possible? I observed H. tuberosus become "H. x laetiflorus" in a few years in an abandoned garden on poor sandy soils . The size of the heads, the shape of the leaves and even the pubescence are changed.

Publicado por phlomis_2019 mais de 4 anos antes

Your comment is really interesting.
Here in Tuscany most plants are compatible with H. x laetiflorus but few still seem to conserve the characters of H. tuberosus thus I thought that the phenomenon you described could not occur. Moreover they are mostly sterile so pollen transfer seems to be unuseful for fruit set and characters mixing seems unlikely.

Publicado por blue_celery mais de 4 anos antes

I don't mind. In Central Russia, sunflower thickets are grow near suburban housing, summer cottages, and so on. Over time, the size of the tubers decreases, the leaves become narrower. This is especially fast on poor soils. I do not believe in the conversion of species, of course. But I do not have exact vouchers of H. x laetiflorus.
Every time I see sunflowers, I remember these problems.

Publicado por phlomis_2019 mais de 4 anos antes

Also the decrease in size of tubers is always observed in the Italian presumed H. laetiflorus.
Your comment suggests to get more insight into this issue and that the implementation of a research at the European level with the involvement of researchers skilled in plant genetics could be interesting.
Anyway, just in order to highligh that many observed plants corresponf to the "concept" of H. x laetiflorus, I would go on indentifying plants following the aforementioned references.

Publicado por blue_celery mais de 4 anos antes

Hi blue, thank you also for this card.
Marco

Publicado por naturalista1989 quase 4 anos antes

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