David C. Zlesak
Why do dandelions all look so similar? Other plants that reseed tend to result in individuals that have noticeable differences from each other. These differences among seedlings may be dramatic or subtle and can involve traits such as flower color, petal number, or plant habit. The answer is that dandelions primarily reproduce by apomixis. Apomixis is commonly defined as asexual reproduction through seeds. The embryos are genetically the same as the mother plant and are not the result of the union of two sex cells. Most plant and animal species rely on sexual reproduction to enhance genetic variability among individuals in populations. Variability can improve the chance that at least some individuals will have a competitive advantage when disease or other challenges come. Those individuals will hopefully survive and be able to reproduce in order to perpetuate the species. Dandelions, some turf grass species, and many citrus have a different strategy that uses apomixis. The best, well-adapted individuals clone or copy themselves through seed. A relatively small proportion of embryos are the product of sexual reproduction to support variability, while most are genetic copies of the well-adapted mother plant.
Photo 1: Bob Mugaas