Today’s species is no stranger to cracks in the asphalt and is public enemy #1 to all gardeners and landscapers with a desire for uniformity in their lawns. I spent one lunch break collecting a bagful and discovered that I’m not the only one after this flower.
Everyone knows that dandelions grant wishes. If you pluck a post-bloom dandelion flower and release all the fluff in one blow, you can make a wish. Unfortunately, you’re not doing yourself any favors if your wish is to reduce alien dandelions, as these tufts are actually seeds which are very successful at colonizing new and/or disturbed habitats. They are originally from Europe, but are now very common in North America (found in all 50 states and most Canadian provinces) and East Asia, and are famous in commercials for weed killer.
Distribution map of the common dandelion in the United States and Canada. Dots in the state or province indicate presence. Image credit: www.eFloras.org
Biology and ecological impact of Taraxacum officinale (F.H. Wigg)
The common dandelion is in the sunflower family and form composite inflorescences characteristic of member of Asteraceae. What we would typically consider one “flower” is actually known as a capitulum and is comprised of multiple flowers held together by a receptacle. The common dandelion reproduces asexually to produce seeds identical to the parent in a process called apomixes. There are two stages in dandelion seed production—pre-bloom and post-bloom. A dandelion capitulum in pre-bloom is a cluster of yellow flowers which will self-fertilize and mature. A mature capitulum in post-bloom has exposed seeds that are topped by bristles making it look like a ball of puff. Due to their highly mobile, wind and wish dispersed seeds, invasions can spread rapidly. In addition, common dandelion seeds can remain viable in the seed bank and dangerously wait for favorable conditions in which to germinate.
This bumble bee didn't know it, but he was about to share his dandelion with me. Photo credit: S. Sim
A recent study has shown that pollen from the alien T. officinale can cause reproductive interference with its native relative, T. japonicum which results in lower seed production in native dandelions. Lower seed production of natives results in fewer individuals with which to compete for space and nutrients and an increased likelihood of the alien species displacing the native.
Is it really invasive?
Though the common dandelion is not native to the North America or East Asia and can displace native relatives, there is discussion about its role in wildlife diets. Dandelions readily colonize disturbed and over-grazed habitats, can serve as an important source of food for cattle, wild ungulates, and bears and thus their colonization of some areas such as cattle pastures is encouraged. However, it has also been shown that they can pose a threat to alpine zones and upper forests through competition with conifer seedlings. So the question is if dandelion presence and benefit to local fauna is worth the potential loss of native flora.
And of course, they are edible to people as well. One of our editors is on record referring to dandelions as a “gateway invasive” for aspiring invasivores. In northern Indiana, we are currently in the part of the season where a majority of the common dandelions are in post-bloom, but they’ll all swing back to pre-bloom soon when I’ll collect more so we can try our luck at making dandelion wine.