One of the many things I love about late summer are the throngs of colorful, star-shaped flowers that spring up all over the landscape. Most of us are familiar with the yellow ones (sunflowers). But did you know that the same plant family also includes varieties in purple, pink, red and white? These flowers are all part of the Aster family, Asteraceae, the largest and most diverse group in the plant kingdom.
THE ASTER FAMILY STORY
Indeed, the Aster family is exceedingly large, with numbers in the tens of thousands. According to The Plant List, there are currently over 27,000 known species. You may have noticed some of the flowers’ shared characteristics. Many feature a round central disk surrounded by colorful petal rays.
Gaillardia is a member of the aster family.
However from there, things can get confusing. Although the botanical name, Asteraceae, comes from a Greek word meaning star, people often refer to asters by their common name, daisy.
Still others refer to asters as Compositae. That’s because their blooms are composed of many tiny, individual flowers. (More on that below.)
WHAT’S SO SPECIAL ABOUT ASTERS
In fact, though they may appear as one flower, asters are actually made up of many, all inserted on a single flower head (disk). There are two types of flowers: tubular and ray. Tubular florets are located in the center of the disk. And the ray-shaped florets are found at the perimeter. The ray-shaped florets are what we often refer to as petals.
Zoom in on the photo and you’ll see that the disk is not flat, but domed. And it’s made up of hundreds of tiny tubular flowers.
Leucanthemum (daisy) displaying both tubular and ray florets.
Moreover, within the family, there are many variations. Some members have only tubular florets while others have only ray. And then there are family members like daisies, coneflowers, common sunflowers and asters that have both disks and rays.
The flower head of Globe Thistle contains no petal florets.
Scientists believe that the aster flower head, which also contains seeds and nutrients, helps the plants store energy during periods of drought. It also may contribute to their longevity. In my own experience, I’ve noticed that once established, my aster family members like coneflower, daisy and blanket flower require very little water. And certainly the abundant roadside sunflowers, daisies and asters are living proof of these flowers’ remarkable survival ability.
UNEXPECTED FAMILY MEMBERS
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, both tubular and ray, on the mountain lettuce bloom below.
TAKE THE ASTER FAMILY QUIZ!
Still, despite all these variations, I find that it’s the yellow aster members that are the hardest to identify. Superficially, many of the flowers look alike. But on closer inspection, their disk and ray flowers are all slightly different.
Below are some well-known Aster family members that bloom in late summer and early fall. Can you identify them? (For answers, 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
GREAT ASTERS FOR GARDENS
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 aster species and their value in the garden.
These popular flowers can be found in gardens all over the world. Popular members include: New England Aster, Echinacea, Rudbeckia, Cosmos, Daisy, Fleabane, Dahlia, Coreopsis, Liatris, Blanket Flower, Fleabane, Zinnia, Chrysanthemum, Oxeye daisy and Yarrow.
HERBAL TEAS, MEDICINE AND FOOD
Aster flowers, leaves and roots have been used for millennia to treat various ailments and diseases. These species include Calendula (Pot marigold), Chamomile, Echinacea, Arnica, Endive, Lettuce and Artemisia.
GREAT NECTOR PRODUCERS
Since they bloom late in the summer and into the fall, asters are a great source of nectar and pollen for pollinators. Some of the best producers are Helianthus annus (Sunflower), Goldenrod, New England Aster and Fleabane.
French marigold, Tagetes patula
Some asters are great at repelling insects. The most well-known among them are marigolds. French marigolds are known to repel whiteflies while Mexican marigolds are said to not only stave off insects but rabbits as well. Other effective ‘insecticidal’ species include Tanacetum, False Fleabane and Chrysanthemum.
Ragweed is a member of the aster family.
Weeds are members, too. Dandelion, Ragwort, Ragweed and Sneezeweed are also part of the Aster family.
Want to know more? For a detailed list of Asteraceae, its genera and where the family fits in the plant kingdom, click here for the USDA Natural Resources Conversation Service.