Aster Frikartii Monch
One of the many things I love about late summer are the throngs of colorful, star-shaped blooms that populate the landscape. The flowers congregate along roadsides, drift lazily across meadows and form neat combinations by houses and in town squares. Most of us are well acquainted with the yellow ones (sunflowers), but less aware that the brood also comes in shades of red, pink, purple and white. The flowers are all part of the Aster family (Asteraceae), the largest and most diverse group in the plant kingdom.
The scoop on the Aster Family
You may have noticed some of the flowers’ shared characteristics; many feature a round central disk surrounded by colorful petal rays. The Aster family is exceedingly large and numbers in the tens of thousands. According to The Plant List, there are currently 1,765 genera of flowering plants and over 27,000 known species growing in diverse climates all over the world.
Gaillardia or Indian Blanket Flower
The botanical name Asteraceae comes from the Greek ἀστήρ meaning star, a reference to the star-like shape of the flowers. But some call the family by its common name, Daisy, from the Old English meaning ‘day’s eye’ (a reference to the flowers’ petals that open at dawn.) Still others refer to the Aster family as the Compositae family, since the inflorescence is a composite of many tiny, individual flowers.
What’s special about Asteraceae is that while at first glance they make look like one flower, they are actually composed of many, all inserted on a common flower head. Of these, there are two types of flowers that may occur. Tubular, petal-less florets are found in the center of the flower disk while flat, ray-shaped florets (resembling petals) are found at the perimeter.
Zoom in on the photo and you’ll see the flowerhead is not flat, but actually made up of hundreds of tiny flowers.
Leucanthemum (daisy) displaying both tubular and ray florets
Within the family there are also several variations. Some flowers have only disk florets, others only ray, and then there are members like daisies, coneflowers, common sunflowers and asters that have both disk and rays.
Flower head of Echinops ritro, Globe Thistle, contains no petal florets
Scientists believe the highly specialized flower head, which also contains seeds and nutrients, helps the plants to store energy during periods of drought and possibly also contributes to their longevity. I know in my own experience that once established, my Aster family members like coneflower, daisy and blanket flower do indeed require little water. And certainly the roadside gardens filled with native sunflowers, daisies and asters are living proof of these flowers’ remarkable survival ability.
Of course every family has its outliers, and the Aster family has a few. These include the food crops lettuce, chicory and globe artichokes. Notice the two types of florets on the mountain lettuce below.
Mountain lettuce, Latuca perennis
Perhaps the most difficult members of the Aster Family to tell apart are the yellow ones. Superficially, many of the flowers look alike. But on closer inspection, their disk and ray flowers are all slightly different.
Take the quiz!
Below are some well-known members of the Aster family found blooming in the late summer and fall. Can you identify them? (For answers and a detailed list of these common family members, please see below.)
Answers: (from top) Coreopsis grandiflora, Golden Marguerite, Rudbeckia (Black-Eyed Susan), Helianthus tuberosis (Jerusalem artichoke), Helenium autumnale (Common Sneezeweed), Helianthus annum (Sunflower), Heliopsis helianthoides (Smooth Oxeye), Gaillardia (Indian Blanket Flower), Arnica montana
If you’d like to add some of these beautiful flowers to your garden, or just be able to identify some more members of the family, following is a list of well-known species in the Aster family and their value in the garden.
Rudbeckia (Black-Eyed Susan)
Gaillardia (Blanket Flower)
Herbal Teas, Medicines and food
Calendula (Pot marigold)
Great Nectar producers
Helianthus annus (Sunflower)
Pulicaria (False Fleabane)
For a detailed list of Asteraceae, its genuses and where it fits in the plant kingdom, click here for USDA Natural Resources Conversation Service