Archived Outdoors

Notes from a plant nerd: Aster Family Plants, the Stars of Summer!

A pipevine swallowtail butterfly lights on a green-headed coneflower (Rudbeckia laciniata). Adam Bigelow photo A pipevine swallowtail butterfly lights on a green-headed coneflower (Rudbeckia laciniata). Adam Bigelow photo

Often, when I am giving my introductory talk on the guided wildflower walks I lead, I invite people to play the “What’s That Plant?” game. This is one of my favorite games to play, and the rules are simple. As we are walking along, if anyone notices a plant or flower that I haven’t seen or taught about yet, they can ask, “Hey Adam, what’s this plant?”

Now, if it has a flower on it, there is a good chance I know it, or we can figure it out together. If it is just a green leaf, then I may or may not be able to identify it. If I don’t know it, my answers can range from, “I don’t know” to more snarky responses and diversionary tactics like, “This is a wildflower class, and the green leaf classes are on Tuesdays.” Or, “I’m not sure, it kind of looks like… Oh hey, look over there” and we quickly move on to the next flower that I do know. 

But I also tell my group that if you hear me say, “Oh, it’s in the aster family (Asteraceae)” and I don’t say anything else, that this is a full-on cop-out. The aster family is the second largest plant family in the world and contains over 32,000 different species. In Southern Appalachia, these range from the well-known sunflowers (Helianthus spp.), asters (Symphyotricum spp. and Eurybia spp.) and coneflowers (Rudbeckia spp. and Echinacea spp.) to the less obvious members like pussytoes (Antennaria spp.), rattlesnake roots (Nabalus spp.) and thoroughworts (Eupatorium spp.) The word aster is from ancient Greek, and it means star. 

Sunflowers are among the most recognizable members of the aster family, also known as composites, so I use them to describe the general flower characteristics. Composite flowers are comprised of many small flowers called florets, on a flower head. With sunflowers, there are actually two types of florets, disc flowers and ray flowers. 

Imagine a kid’s drawing of the sun. Where the smiley face would go are the disc flowers. These are the fertile florets that produce pollen and nectar and ripen into seeds. The bright, showy rays of the sun are called ray flowers. These florets are sterile, containing no nectar or pollen, and they help insects see the flower from afar, guiding them into the center to find the nectar and help with pollination. I like to describe them as similar to a billboard advertising a restaurant at the next exit. If you go to the billboard, you won’t get lunch. But the billboard will tell you how to get there and get a meal. Often, these ray flowers are very colorful, and if you could see them like many insects do, using ultraviolet light, they would be lit up like an airport runway at night with markings and patterns pointing towards the center of the flower. These are known as nectar guides. 

Some members of the aster family, like goldenrods (Solidago spp.) and ironweeds (Vernonia spp.) have flowers that are all disc, no rays. Without the ray flowers, it is not always obvious to the casual observer that they are in the aster family. I like to teach this in the fall by pulling the ray florets off an aster like frost aster (Symphiotrichum pilosum), often while chanting “She loves me, she loves me not, she used to love me, now she doesn’t, and …” oh, sorry. I get carried away. I then compare this plucked petal flower to a rayless flower like that of goldenrod or white snakeroot (Ageratina altissima) to show their similarities.

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So, remember, if you want to sound smart (and who doesn’t) the next time someone asks you what that plant is, just say it’s probably in the aster family, and walk away. There’s a good chance you’ll be right. 

(Adam Bigelow lives in Cullowhee and leads wildflower walks and ecotours through Bigelow’s Botanical Excursions. This email address is being protected from spambots. You need JavaScript enabled to view it..)

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