This native species is highly adaptable

JOHN NELSON University of South Carolina

For some reason I have never written about our real sunflowers in this column…which is a perplexity, as sunflowers are some of the most interesting native species we have in the Southeast.

All our sunflowers belong to the genus Helianthus (meaning “sunflower,” of course!), a member of the sunflower family, or Asteraceae. We’ve had many other members of the sunflower family in this column, but not this one so far.

You will recall that family members are instantly characterized as having very small individual flowers packed into buds.

The buds are surrounded at the base by a series of bracts, which provide protection for the flowers before the bud is fully developed.

In general, each little flower has an ovary down to the base…a “lower” ovary, which is destined to grow into a hard single-seeded fruit, if all goes well.

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You should know that all these different parts of the plants, including the roots, the stems, the foliage, and of course the heads with their flowers, and many other details, are subject to wild and characteristic variations of a kind. to the other. , which makes sense: they are the largest family of plants on earth, with more than 1,500 different genera and almost 23,000 different species! (The other two very large plant families in terms of the number of genera and species are the orchid family and the bean family, in case you were wondering.)

This week’s Mystery Plant is a native sunflower known to grow from South Carolina to Texas, a resident of the Coastal Plain. It was formally described in 1929 by a botanist named Elba Emanuel Watson (1871-1936). He received his doctorate from the University of Michigan after writing a thesis on all known sunflowers.

Watson only knew of this plant from specimens collected in Louisiana, from “very wet black mud”, although he suggested that it might grow in other “Gulf States”. He was struck by the similarity it had with the more widespread species named Helianthus angustifolius, commonly called “swamp sunflower”, which is the more common of the two species. Of these two species, our Mystery Plant tends to be much taller and with broader leaves, producing well-elongated rhizomes below the ground.

It is one of those native species that adapt to garden situations, which over the years has become very popular in cultivation.

Several years ago, on a trip to the Lowcountry, I saw this plant growing in the yard of an old cabin, having been planted there years before. It was in full bloom and the tops of the plants reached the roof. Quite a show!

I grow it in my garden and during my walks in the neighborhood, I often see it planted. It’s a real beauty: when there’s enough room, plenty of sun, and plenty of water, the stems can grow nearly 10 feet tall and are truly impressive in full bloom. Bees love it and it is easy to grow. (If I can grow it, anyone can.)

John Nelson is the retired curator of the AC Moore Herbarium at the University of South Carolina at Columbia SC. As a public service, the Herbarium offers free plant identifications. For more information, visit or email [email protected]

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