The Aster Family

One of the largest plant families is the world is the Aster Family or Asteraceae. Sometimes still referred to by its older name Compositae for its “composite” heads of small flowers that look like single large blooms, this plant group encompasses over 1,000 genera and about 20,000 species.

To illustrate the classic flower form, take the Aster Family member, the daisy, with its center of hundreds of tiny “disk” flowers packed together, surrounded by a halo of “ray” flowers. Flower heads like this make a perfect “landing pad” for butterflies so they can perch and enjoy a meal from multiple nectaries. If you want a butterfly garden, the Aster Family is absolutely essential. Exceptions to the disk/ray arrangement are all-ray flowers, like chicory, and all-disk flowers, like thistles.

Having lots of flowers also means lots of tasty seeds, and plants like black-eyed Susan, purple coneflower, and sunflowers are feeding stations for songbirds like goldfinches, chickadees, and cardinals. So when growing some of these plants in the garden, refrain from removing all the spent flowers – leave some to produce seeds for hungry birds.

The Aster Family is one plant group that can be counted on to fill the garden with color throughout the growing season. Spring brings English daisies, calendula, bachelor’s button, and golden ragwort. In summer the border glows with zinnias, dahlias, yarrow, cosmos, blazing star, floss flower, marigolds, coreopsis, and gaillardia. And in late summer and fall, the landscape would seem empty without goldenrods, asters, ironweed, Joe-Pye weed, and chrysanthemums. Many of these can bloom for months; others can be encouraged to keep flowering by deadheading (cutting off old flower heads). Wormwood, or Artemisia, has such beautiful silvery foliage that it doesn’t even need to bloom.

A number of aster relatives are blessed with long, sturdy stems, bountiful blooms, and staying power, making them ideal cutting flowers for arrangements. They can last for days, even a week or so, in a vase. If you’re an arranger, be sure to include enough Aster Family plants to cut from, while still leaving plenty to enjoy out in the garden. A few of the best cut-flower choices are dahlias, coneflowers, zinnias, cosmos, gerbera daisies, and pollen-free sunflowers like ‘Van Gogh’, ‘Pristine’, and ‘Gold Rush’.

Even some vegetables and herbs are members of the Asteraceae: chamomile, artichoke, endive, tarragon, lavender cotton, safflower. And it might come as a surprise to many gardeners that lettuce, too, is related to daisies and asters. Usually lettuce is pulled up and thrown away when it starts to send up a flower stalk, called “bolting,” since its leaves become bitter after that. But if the heat of summer sneaks up on you and your lettuce does flower, it can be an attractive element in the garden and a conversation starter with fellow gardeners.

Interestingly, a few all-too-familiar weeds are also in the Aster Family, such as dandelion and ragweed. While the pollen of most plants in the Asteraceae is too heavy to be carried on the wind (hence the colorful flowers to attract insects to move the pollen from flower to flower), ragweed, which has small, greenish, non-descript flowers, is an exception. Since it blooms at the same time as more eye-catching plants, the showy flowers often take the blame for hay fever symptoms. But if you’re sneezing in late summer and fall, point the finger at ragweed not the innocent goldenrod!