||Helianthus petiolaris subsp. fallax
||Helianthus petiolaris subsp. fallax is one of two subspecies of Helianthus petiolaris, the prairie sunflower, an annual, branched sunflower species. H. petiolaris subsp. fallax is native to the South-West of the US. Populations of H. petiolaris subsp. fallax have epeatedly adapted to sand dunes habitats. Together with other wild sunflower species, it is a long-standing model system for speciation, adaptation and ecotype formation studies, and, more recently, genomic studies. Wild sunflower species, including Helianthus petiolaris, have also contributed numerous useful alleles to the cultivated sunflower gene pool.
Helianthus petiolaris subsp. fallax is diploid and has a relatively large (3.3 Gbp), extremely repetitive genome, organized in 17 chromosomes. Numerous large chromosomal rearrangements and structural variants distinguish its genome from that of other wild sunflowers. Several multi-Mbp inversions distinguish dune-adapted from non-dune-adapted Helianthus petiolaris subsp. fallax, and are associated to several dune-specific traits.