Sunday, April 23, 2017

THE FLOWER WE LOVE TO HATE




THE FLOWER WE LOVE TO HATE

Dandelions are not native to the United States. Europeans immigrating to the United States brought the bright yellow flowered plant with them because of its many properties. There are records mentioning dandelions in the United States as early as 1672 and these most likely came over with pilgrims on the Mayflower (1).  The plant has traditionally been used to treat many ailments such as fever, boils, rotting gums, or stomach problems. Today it is still widely used but mainly as a diuretic. It is also valuable as a food and beverage plant. Leaves can be eaten as greens in a salad and are full of vitamins and minerals. Other parts of the plant can be used to make wine, tea, a natural yellow dye, and a coffee substitute (2) (3).


Figure 1: Dandelion flowers of Taraxacum officinale the common dandelion. 

Although dandelions originated from Eurasia they are now found world-wide. They are commonly found in yards, pastures, along roadsides, and disturbed areas. Like many successful introduced species they are well adapted to spreading into new territories. They can produce flowers multiple times through-out the year and produce large amounts of airborne seeds that allow them to travel long distances and invade new habitats. Dandelions can also produce viable seeds without fertilization, a process called apomixis, which allows them to spread even when pollinators are not available.



Seed head of Taraxacum erythrospermum, note the modified pappus hairs that function as a parachute to aid in wind dispersal of the seeds.
However, unlike many other “weedy” plants, dandelions do not spread asexually by rhizomes, stolons, or bulbs. They are perennials with long taproots that anchor them firmly into the soil and allow them to store food. So grazing, mowing, or breaking the plants off at ground level is futile. The hardy plants quickly sprout back from their taproots and once established they are hard to eradicate.

Dandelions are members of the family Asteraceae. The pinnately lobed leaves form a basal rosette and hollow scapes terminate in a single yellow head of ray flowers. The leaves and scapes exude a milky latex when damaged.



Figure 2: Typical morphology of a ray flower in Asteraceae. 
Drawing by Tracie Jeffries


There are two species of dandelion found in North Carolina, Taraxacum officinale and T. erythrospermum. They appear extremely similar and I find the best way to identify them is by their seeds. Taraxacum officinale has olive colored cypsela and T. erythrospermum has red cypsela. 


Figure 3: Taraxacum erythrospermum with red cypsela.  




Figure 4: Taraxacum officinale with olive green cypsela. 

There are also differences in the leaves but, the leaves of T. officinale can vary greatly making identification based on leaves difficult. According to Weakley, leaves of T. erythrospermum are deeply divided along entire length of leaf where as T. officinale are less deeply lobed especially towards the base of leaf (8)


Figure 5: Leaves of Taraxacum officinale the common dandelion. 

Dandelions are beautiful flowers that bloom through out the year. They provide food for many pollinators such as the Red Admiral (Vanessa atalanta), Painted Lady (Vanessa cardui), American Copper (Lycaena phlaeas), and various bee species (4).


Figure 6: Honey Bee pollinating a dandelion flower. 

It can also serve as a host plant for several species of butterflies and moths such as the Giant Leopard Moth (Hypercompe scribonia) (5).
  


  
Figure 7: Giant leopard moth, Hypercompe scribonia 
(Stoll 1790). Photograph by Donald W. Hall, University of Florida.

According to “American Green: The Obsessive Quest for the Perfect Lawn” Americans spend an estimated $40 billion caring for their lawns per year (6). Most of that is aimed at eradicating “weeds” such as dandelions from our yards. But perhaps we should reconsider the dandelion, save ourselves a lot of work and money, and embrace it as an important naturalized species that provides many benefits to wildlife and adds color and beauty to the landscape. 


Figure 8: Dandelions along the Blue Ridge Parkway.

Note: All photographs are taken by the author Tracie Jeffries unless otherwise indicated.

Resources:

1_ Keeler, Kathleen. "A Wandering Botanist." Plant Story: Common Dandelions of the World. N.p., 01 Jan. 1970. Web. 19 Apr. 2017.

2_ "Dandelion." University of Maryland Medical Center. N.p., n.d. Web. 19 Apr. 2017.

3_ "Natural Dyeing with Dandelions, FiberArtsy.com." FiberArtsy.com. N.p., 19 July 2016. Web. 19 Apr. 2017.

4_ Ballard, Kelly. "What Do Butterflies Eat? Nectar Plants (generally)." Butterfly Plants, Seeds, Photos & Tips For Your Garden. N.p., 29 Apr. 2015. Web. 19 Apr. 2017.

5_ Giant woolly bear, great leopard moth - Hypercompe scribonia (Stoll 1790). N.p., n.d. Web. 19 Apr. 2017.

6 _ Steinberg, Theodore. American green: the obsessive quest for the perfect lawn. New York: W.W. Norton, 2006. Print.

7_ Radford, Albert Ernest, Harry E. Ahles, and Clyde Ritchie Bell. Manual of the Vascular Flora of the Carolinas. Chapel Hill, NC: U of North Carolina, 1983. Print.


8_ Weakley, Alan S. Flora of the Southern and Mid-Atlantic States. Chapel Hill, NC: U of North Carolina Herbarium, North Carolina Botanical Garden, U of North Carolina, Chapel Hill, 2015. Print.asexually