Thursday, July 22, 2010

LOOK FOR: Rose Mallow, our local hibiscus

I always thought of hibiscus as a tropical flower. It's the kind of thing you expect to see printed on Hawaiian shirts, or tucked behind a hula dancer's ear. But we've got native hibiscus right here in DC.

hibiscus laevis at Jug Bay
Hibiscus at Jug Bay by the Natural Capital

Unlike the bright red tropical hibiscus, our native hibiscus has five petals that can range in color from light pink to white, with a darker magenta center. Protruding from that dark center is a showy yellow set of reproductive parts: a tube covered in pollen-producing stamens, with five pollen-collecting pistils branching out on the end. The flowers can be six inches across, on stalks that reach 5 (or more) feet high. It's quite an impressive plant.

bee pollinating hibiscus
Bee pollinating hibiscus, by Mean and Pinchy
The name Hibiscus covers a large genus of related plants. We have at least two native species in the DC area: Hibiscus laevis, often called halberd-leaved rose mallow, and Hibiscus moscheutos, or swamp rose mallow.  We usually are happy to just say "hibiscus" or "rose mallow," and leave it at that.  But if you want to get to the species, remember that laevis means smooth -- Hibiscus laevis has smooth leaves; Hibiscus moscheutos has leaves with hairy undersides.

The genus Hibiscus also includes the imported Rose of Sharon (Hibiscus syriacus), which many people have in their yards. But the flowers of Rose of Sharon don't get nearly as large as our native hibiscus -- maybe 4 inches across as opposed to 6 inches or more.

pink swamp rose mallow
Pink rose mallow by Urtica
In my experience, the best time to catch rose mallow blooms is in the morning. By afternoon, they fold up as protection against the heat. Each flower is short-lived, but each plant produces many flowers. And each flower produces a seedpod about an inch in diameter. These can be showy in their own right in the fall and winter, when they bust open along five lines, leaving an open pod that looks almost like a dried flower itself.

In the wild: Rose mallow likes wetlands. We've seen it growing at Roosevelt Island, and there's lots of it at Jug Bay. I'm sure it's in other spots as well.

In your yard: We're growing rose mallow that we started from wild-collected seed in our raingarden and in our dry backyard; it seems to be thriving in both locations. So, even though it grows in marshy areas naturally, it doesn't seem to require them.  It does need at least several hours of sun to bloom well, though.

Where have you seen hibiscus growing? Leave us a comment!


Mike Ronayne said...

Are you growing the all-pink Hibiscus with no red-eye and if so where did you collect it? From the small glimpse of the leaf of the all-pink Hibiscus, which is visible in the photograph, this looks like Hibiscus laevis. Last month I was studying a wild population of Hibiscus moscheutos on the southern tip of Cape May NJ and another population just north of Atlantic City NJ. I was surprised at the small numbers of Hibiscus I observed in NJ compared to the Delmarva Peninsula DE last year. I am troubled by the “wild” population north of Atlantic City which had a very high percentage of pink flowers compared to white.

Michael Ronayne
Nutley, NJ

Elizabeth | The Natural Capital said...

We've got white-and-red flowers from seed we collected at Jug Bay Wetland Sanctuary. They have some pink ones in their population there but definitely more white.

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