Mystery Plant! #744

John Nelson

Posted 10/11/23

By John Nelson

(Photo by John Nelson.)

Most of us have been thinking that this past summer was really long, hot one. Then they say that this has been the hottest year on record, temperature-wise. This climate change business has very important effects on our local plant life, but now that it’s been cooling off (Halloween decorations are already up!), we ought to remember that day length is what is really driving a lot of natural processes. Day length has been steadily been decreasing (just as night length has been increasing), since the summer solstice. Have you noticed yet? Day length is of crucial importance to many biological systems involving plants and animals. For plants, day length is important in signaling a variety of responses, such as blooming and the ripening of fruits… as well as slowing things down, and getting ready for a physiologically “quiet” winter period. As far as blooming goes, though, what a spectacular time early autumn is! Here’s one example of a naturally-occurring species that is starting to bloom its “heads” off.

“Heads” in the sense of a head (or capitulum) of flowers, because our Mystery Plant is a member of the sunflower family, or Asteraceae. The individual flowers of each species in the family are small, and arranged in variously sized heads. Within one of these bract-surrounded heads will be anywhere from 50 to 100 separate, tubular flowers, each bearing its own stamens and pistil. Because the heads are typically composed of a lot of small flowers, they are often referred to, as a group, as “composites”. Each head is surrounded by a series of tightly overlapping bracts, which eventually spread out, allowing the new flowers to spread out as well, awaiting busy visitors. After pollination, the ovary of each flower will develop into a hardened, one-seeded fruit, or “achene”, which is basically the same as an unshelled “seed” of a sunflower. There will be a tuft of bristly hairs at the tip of the achene.

When the plants are in full bloom, they make a dramatic display of bright golden-yellow, some of the most conspicuous wildflowers you can see. This is a variable species, though, and depending on where you find it, can exhibit a range in degrees of size and hairiness, and branching. The stems are generally erect, and often branched from the base. It occurs widely, from Rhode Island to Texas, and in a good many different habitats, mostly dryish, and either sandy or rocky.

This plant is but one of a large group of yellow-flowered composites. In fact, there are hundreds of species of such plants across North America, and indeed elsewhere, and these plants are often similar in habit and other characteristics. As you might expect, such plants as a group in a given local area take special study when it comes to proper identification. Some people who are not patient enough to carefully learn their differences will throw up their hands and call them all “DYC”s….meaning “darn yellow composite”. Or something similar. 

[Answer:  “Maryland golden-aster”, Chrysopsis mariana]

John Nelson is the retired curator of the Herbarium at the University of South Carolina, in the Department of Biological Sciences. As a public service, the Herbarium offers free plant identifications. For more information, visit or email

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