Aster Flowers: Your Guide To Who’s Who In The Family

One of the many things I love about late summer are the throngs of colorful, star-shaped flowers that pop up all over the landscape. Most of us are familiar with the yellow ones (sunflowers). But did you know that the same family also produces flowers in purple, red, pink and white? These plants 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 (also known as Compositae and daisy) is exceedingly large. There are estimated to be over 27,000 known species. They may differ in color, shape and form, but most share two key characteristics. Most plants are composed of two types of flowers, disc and ray.

Gaillardia is a member of the aster family.

Yes, they may look like one flower, but asters are actually composed of many, all fused onto a single flower head. Disc flowers are located in the center and ray flowers are found at the perimeter. The ray flowers are what we commonly 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 flowers.

Leucanthemum (daisy) displaying both tubular and ray florets.

That said, within the family, there are also deviations. Some species consist of only disc flowers while others have only ray. 

The flower head of Globe Thistle contains no petal flowers.

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 many 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 flowers, both tubular and ray, on the mountain lettuce bloom below.

Mountain lettuce

TAKE THE ASTER FAMILY QUIZ!

Despite all these variations, I still find the yellow asters the hardest to identify. At first glance, many of the flowers look alike. But on closer inspection, their 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

Ready 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.

ORNAMENTALS

echinacea purpurea

Echinacea purpurea

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

arnica flower

Arnica flower

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

fleabane

Fleabane

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.

INSECTICIDAL PROPERTIES

French marigold

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.

WEEDS

ragweed

Ragweed is a member of the aster family.

Weeds are members, too. Dandelion, Ragwort, Ragweed and Sneezeweed are all 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.

Looking for garden inspiration? To see photos of my designs, including plant lists, check out my Instagram at carole.herebydesign. I post seasonally from spring through fall. 

 

Pruning Hydrangeas: A Step-By-Step Guide For Old And New Wood

To prune or not to prune? This is one of the quintessential gardening questions. Recently, I asked a top landscaper in Virginia to weigh in on the issue. “When is the best time to prune hydrangeas without cutting off next year’s flowers?” I asked. 

“Never,” she replied with a laugh. “But your best shot is after they’ve bloomed.”

It turns out that knowing how and when to prune hydrangeas involves first, identifying what kind of shrubs you own. And it all starts with determining whether they flower on old or new wood. Continue reading

How To Build The Perfect Monarch Butterfly Garden

monarch on pink flowers

Daniel Potter freely admits he’s not an expert on monarchs. But as Professor of Entomology at the University of Kentucky, he and his grad students sure love to run experiments. Recently, they completed a two-year study on the likes and dislikes of the popular orange and black butterfly. Now for the first time ever, there’s a roadmap for building the perfect monarch garden.

WHY WE CARE

If you’re reading this post, you’re probably already a monarch fan. The butterflies’ annual migration from Mexico to Canada is one of the most spectacular events worldwide. All told, the tiny insects fly upwards of 2000 miles roundtrip each spring, stopping four times to breed and lay their eggs. They are the only butterfly species to make such a long, two-way migration.

monarch migration

Over the past 25 years, however, there’s been a sharp decline in monarch populations. Part of this is due to a loss of habitat at the butterflies’ overwintering site in Mexico. Activities such as logging, agriculture and urbanization have all taken their toll on the central highland forests that play host to the insects six months out of every year.

But by far the most significant factor driving the decline is the dwindling supply of a plant called milkweed. The native wildflower is the only plant that monarch caterpillars will eat. And without it, the butterflies cannot complete their life cycle, sustain their migration and ultimately, perpetuate their species.

monarch feeding on milkweed

MONARCH BUTTERFLY GARDENS NEED MILKWEED 

According to the North American Monarch Conservation Plan, we need 1.8 billion milkweed stems to replace those that have been lost to agriculture and urbanization. And to sustain the annual migration, these contributions need to come from all land sectors. This includes farms, roadsides, schools, zoos and rights of way. And it also includes suburban and urban gardens located along the butterflies’ migratory corridor.

Happily, an initiative called the Monarch Waystation Program is starting to make a crucial difference. Established in 2005, it engages citizens in conservation by providing instructional materials on how to build and maintain your own monarch habitat. The guidelines are simple: Plant two or more milkweed varieties for the caterpillars to feed on along with some nectar sources for the adults, and you become part of a national registry.

To date, over 6000 Monarch Waystations in 46 states have become part of the effort. 

WHAT MONARCHS LIKE

As it happened, the Waystation Program Registry provided the perfect jumping off point for Potter’s research into monarch butterfly gardens. A quick Google Earth search by his team revealed hundreds of habitats scattered along the butterflies’ northward route. What’s more, they represented every kind of landscape.

As Potter put it, ‘Some were non-structured, others ‘wild’, and still others were surrounded by hardscape or located in open rural areas.’ Below are some aerial shots of a few of them. (Photo courtesy Dr. Daniel Potter.)

What Potter and his team wondered was this – with all of this diversity, were there certain habitats that the butterflies found more attractive than others? To find the answer, the group decided to survey 22 citizen-planted Waystations. Below are some key outcomes from their investigation. 

1. MONARCHS LIKE STRUCTURE

Like most species, monarchs use visual cues to zero in on what they’re looking for. And in the butterflies’ case, these ‘search images’ are made up exclusively of milkweed. But as the Registry revealed, not all Waystations are the same. Did monarchs favor certain monarch butterfly gardens over others?

Monarchs from ‘search images’ for milkweed

To find out, the researchers counted larvae and caterpillars for a year in their target Waystations to see if the type of habitat made any measurable difference.

monarch caterpillar on milkweed leaf

Monarch caterpillar on milkweed leaf

And they discovered that yes, the butterflies exhibited a strong preference. A structured garden, with milkweed surrounded by mulch, attracted three to five times more monarchs.

The takeaway? If you want more monarchs, make it easy for them to find the milkweed to lay their eggs on. Plant it apart from other plants. Even better, surround it with a mulch circle. But make sure to provide other nectar producing plants nearby for the returning adult butterflies to feed on.

2. MONARCHS PREFER A NORTH-SOUTH ACCESS

Interestingly, the researchers found that gardens with unimpeded north-south access recruited more monarchs. This makes sense since it coincides with the butterflies’ migratory route.

monarch migration map

Monarchs prefer gardens with a north-south access

3. THE TALLER THE BETTER

While all milkweed species are suitable for food, not all are equally favored by monarchs. To find out why, the group compared 8 varieties of milkweed all grown in Kentucky and native to the area. They evaluated them as to their suitability for egg-laying as well as their usability as food for monarch caterpillars. And there was a clear preference.

Where they had a choice, monarchs preferred the taller varieties, Swamp, Common and Showy over the smaller varieties like Butterfly weed

The takeaway? If you want to attract more egg-laying monarchs to your monarch butterfly garden, plant the tall, broadleaf milkweed varieties.

4. MILKWEED CULTIVARS ARE EQUALLY TASTY

But what about all of the new milkweed varieties, you might ask? As it has grown in popularity (mainly due to monarchs), milkweed is now available in many cultivars boasting unusual colors and sizes.

Asclepias Gay Butterflies Mix/White Flower Farm

Not to worry. Potter and his students discovered that monarchs find these cultivars just as attractive as the straight species. But again, go with the bigger varieties if you want more monarchs.

5. DON’T BECOME AN ECOLOGICAL TRAP

Finally, there’s the case of tropical milkweed, a non-native plant that has exploded in popularity over the past decade. Both gardeners and monarchs love it. But buyer beware. Tropical milkweed is not ‘bad’, per se, but when planted in warm areas of the U.S. it encourages monarchs to stick around longer. It even enables them to winter-breed.

tropical milkweed

Tropical milkweed, Asclepias curassavica

Research shows, however, that monarchs breeding on tropical milkweed throughout the winter (rather than returning to Mexico) have higher levels of protozoan infection compared to monarchs in the normal migratory cycles. It turns out that migration is key to outrunning these pathogens.

The takeaway? Stick to the tried and true native milkweed species and help the insects keep to their schedule.

To learn more about Daniel Potter and his research into monarchs and other insects, click here for the Dr. Daniel A. Potter Laboratory.

This article was updated January 2022.

Top Annuals for the All-Season Cutting Garden

Annuals for the cutting garden/Photo: Julie Hove Anderson Photography

As a landscape designer, I’m well versed in perennials and the kind of annuals you buy from a nursery. But when it comes to growing annuals from seeds, my experience lies mainly with zinnias. So recently, I was delighted to attend a webinar hosted by ButterBee Farm owner Laura Beth Resnick on the top annuals she grows for her cutting gardens. Continue reading

Identify Plants In A Snap With These 6 Top Apps

 What's That Flower app

Now that we’re all spending more time at home, it can’t hurt to know what’s blooming. And finding the answer is easier than ever with one the many plant identification apps available. But which ones work best and provide the fastest, most reliable data? To find out, I decided to do a side-by-side comparison. Continue reading

Finally, A ‘Phenomenal’ Lavender That Looks Good All Winter

They said it couldn’t be done, but finally, there’s a new kind of lavender that looks good all winter. Appropriately dubbed ‘Phenomenal’, it’s so good that it’s now being used for municipal plantings. To understand the hype, I purchased a few plants for a trial run. What I discovered was nothing short of, well, phenomenal. Continue reading

Meet Stevia Rebaudiana: The Plant Behind the Hype

stevia rebaudiana

Last week, I was vacationing in Canada when an interesting commercial appeared on the TV. It was an ad for the sweetener, stevia, featuring enthusiastic consumers growing plants at home. Needless to say, it caught my attention. I had heard that stevia extract came from a ‘natural’ source. But I’d never stopped to consider what that meant from a gardening perspective.

I decided to dig deeper. Continue reading