|Helianthus argophyllus, the silverleaf sunflower, is an annual, branched sunflower species, the sister species to H. annuus. Native to North America, is found exclusively in coastal and inland Southern Texas. Two very distinct ecotypes can be found; an early flowering coastal island ecotype and a late flowering inland ecotype. 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 sunflowers, including H. argophyllus have also contributed numerous useful alleles to the cultivated sunflower gene pool.
H. argophyllus is diploid and has a relatively large (4.3 Gbp), extremely repetitive genome, organized in 17 chromosomes. Numerous large chromosomal rearrangements and structural variants distinguish its genome from that of other wild sunflowers, and of cultivated sunflower. A 30 Mbp region introgressed from H. annuus, containing a functional allele of the HaFT1 flowering time regulator, causes early flowering in the coastal island ecotype.