Mystery Plant: Plant attracts pollinators with pungent scent

Yes, it is hot. Time for everyone to take a deep, air-conditioned breath, and figure out ways to deal with the weather.

One way is to remember that before long there will be signs of autumn and eventually everything will be cooling off, with displays of autumnal blooming everywhere. Our Mystery Plant is one of the autumn-bloomers, and it packs an olfactory punch.

Plants around us aren’t always the sweetly fragrant charmers that the poets would like us to think — no-siree. Various kinds of flowering plants are downright stinky, and of course whatever the scent produced, whether sweet or foul, there is always some biological connection to it.

We tend to think that flowers in bloom are always sweet, think roses, gardenias, and Easter lilies. But consider also the various voodoo-lilies (Amorphophallus and relatives), or starfish flowers (the succulent stapeliads), which when in bloom suggest a dead rat in the vicinity and tend to attract flies — not such a good idea for an arrangement on your dinner table.

The whole idea of floral fragrance presumably involves attracting pollinators, whether the scent is sweet or foul. Of course, beauty is in the eye of the beholder — or in this case, the smeller. In a sense, various plant groups have evolved strategies to maximize pollination by using whatever kind of attractant is the most effective. It’s a floral version of the modernism, “Whatever works!”

It’s interesting to know that some fascinating botanical research involves the identification of these various compounds. Floral fragrances can be studied by basically sucking the air (and fragrance) from a flower and then injecting all these fragrances into a special machine — a gas chromatograph — to isolate and identify the various compounds.

Otherwise, stinky plants are often stinky because of various compounds in the foliage or internal tissues. A wide variety of organic compounds is thus useful in discouraging attack from predators (mostly insects). That’s the case this week.

Our Mystery Plant is a resident of damp meadows, ditches and swamp margins throughout the eastern United States, including Texas, Oklahoma and Kansas. It’s a member of the sunflower family “Asteraceae,” as you have guessed from the image, with its flowers surrounded by tiny bracts, each head referred to as a capitulum.

This plant, with its handsome, bright green leaves, has quite a number of similar relatives in the same genus, and the various species are sometimes hard to tell apart. With this species, the tiny flowers are pinkish, and so are the bracts that surround them. Each flower in a capitulum will produce a tiny, dark seed, much like a sunflower will, but that’s not too important here.

These bracts, as well as the flower stalks, stems and leaf surfaces, are essentially covered with thousands of dot-shaped glands, each one full of a pungent, stinky oil. The oil is also a bit sticky.

Walking through a field of this plant, or handling it for whatever reason, will give you the impression that there might have been a cat somewhere nearby — or maybe a lot of cats. Cats that like to drink beer.

(Answer: “Camphor stinkweed,” “Fleabane,” Pluchea camphorata)