All hybrid plants from interspecific crosses among the three species, Sonchus asper (L.) Hill, S. oleraceus L., and S. arvensis L., were male‐sterile, but the progeny of the cross S. arvensis X S. oleraceus and reciprocal cross produced seed after backcrossing to the male parent. Hybrid plants from crosses between S. oleraceus and S. asper lacked vigor. Cytological data indicated that S. arvensis has one genome in common with S. asper and that S. oleraceus is an autotetraploid (2n = 36) with no genomes in common with S. arvensis or S. asper.
Interspecific crosses were made between perennial sowthistle (Sonchus arvensisL.) and annual sowthistle (Sonchus oleraceusL.). Flower head size, leaf type, and creeping root growth of the hybrid were intermediate to those same morphological characteristics of the parents. Backcrosses to the parents produced plants which resembled annual or perennial sowthistle more closely than did the F1hybrids. Annual sowthistle and backcrosses to annual sowthistle were more tolerant to (2,4-dichlorophenoxy)acetic acid (2,4-D) and 3,6-dichloro-o-anisic acid (dicamba) than were perennial sowthistle or backcrosses to perennial sowthistle. However, annual and perennial sowthistle were similar to each other in response to 4-amino-3,5,6-trichloropicolinic acid (picloram). Natural crosses between annual and perennial sowthistles may account for some of the variability in herbicide response found in perennial sowthistle.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.