It won't be long until the first dandelions (Taraxacum officinale) of the season will be popping up in lawns, gardens, and roadsides. While some may consider dandelions the scourge of a manicured lawn, others relish the thought of collecting these greens for a meal or picking flowers for a batch of dandelion wine. Either way, the dandelion is an interesting and tenacious perennial plant.
Dandelions are short-day plants, requiring 12 hours or less of light each day to form flower buds as the basal rosette of leaves develop. This is the reason they bloom both in the spring and the fall. After floral buds develop, it only takes 48 hours for the leafless flower stalk (i.e., scape) to elongate and elevate the flower above the leaves. During bloom, various types of insects collect pollen from the blossoms, including bees. While one might think cross-pollination is occurring as insects visit dandelion flowers, it is not. Dandelions in the United States are triploids, having three sets of chromosomes, and most of its pollen grains are infertile.
After only one day of bloom, the flower closes. Seeds then develop apomictically, without fertilization. The white puffy "seed head" at the end of a scape is composed of many brown fruits, called cypselae. The feathery attachment on the cypselae is called the pappus, which aids in the dispersal of the seed. Spectacular close-up views of the flowers and fruits are posted at: http://www.microscopy-uk.org.uk/mag/indexmag.html?http://www.microscopy-uk.org.uk/mag/artjun10/bj-dandelion.html.
The fleshy taproots of dandelions are also fascinating (or nightmarish)! Taproots are contractile and can pull the crown snuggly against the soil surface or even below ground, making it difficult to dig or remove the plant. Taproots can grow up to a foot-long and when wounded, they produce callus tissue and two to five new shoots develop, eventually producing that many new plants! For this reason, chemical control may be a better alternative for eliminating these plants from the home lawn rather than digging. Products containing 2,4-D are widely available for post-emergent applications in the spring and fall.
The lowly dandelion has come a long way. This plant is native to Eurasia, but was known to Arab physicians in the early Middle Ages for its herbal properties in aiding digestion. It is thought that dandelion was first introduced into North America in 1620. Seeds transported onboard the Mayflower were planted in the colonies as a food crop, with dandelion leaves providing a source of vitamins and minerals for early settlers.
As dandelions spread across the continent, native peoples soon used dandelions in several ways. The Ojibwa of northeastern North America made tea from dandelion roots to treat heartburn. Kiowa women brewed tea from the flowers to alleviate abdominal spasms. Southern Paiute people of the Colorado River basin and the Apaches of Arizona consumed dandelion roots. From 1831 to 1926 dandelions were officially listed in the U.S. Pharmacopoeia, a published compendium of medicinals.
Many myths are associated with blowing on dandelion seed heads. For example, if after one strong puff, all the seeds are gone, you are loved. If some remain, your "intended" has some doubts. For young girls that blew on a seed head, the number of seeds left indicated the number of children she would bear later in life. However, for elders, the number of seed left represented the number of years left to live. However, a surer bet is that the number of seeds blown from a dandelion scape is a good estimate of how many plants you'll deal with in the future!
REVISED: February 21, 2017