Science & nature
Yellow Hibiscus blooms in coastal swamps

In flower right now is one of the prettiest local Hibiscus plants, the Swamp Hibiscus or Hibiscus diversifolius. And that's really saying something, as Illawarra is home to the splendid Hibiscus splendens, which I featured a few weeks back. 

Swamp Hibiscus, with its appealing yellow flowers with their maroon centres, is a sprawling shrub that reaches 1-2m high, though usually towards the lower height in this region. It occurs in swampy coastal areas, where it grows in and among a range of sedges, rushes and other inundation-tolerant shrubs and trees. 

This shrub has the advantage (for appreciation by humans) of bearing its flowers at about head-height or a little lower, so they can be easily seen and enjoyed. And now is the perfect time to check out Swamp Hibiscus, when its flowers make it quite conspicuous.

Swamp Hibiscus (Hibiscus diversifolius), a shrub of damp swampy areas, showing off its beautiful yellow flowers with a maroon centre. It also has striking flower buds, seen here below the open flower. Photo: Emma Rooksby. 

Unfortunately Swamp Hibiscus isn't super-common around Illawarra these days, in part because the coastal swamps it calls home have been largely cleared or filled in or otherwise developed.

That said, the coastal walking and bike track in Thirroul runs right by a big patch of Swamp Hibiscus so it's easy to spot there (just to the east of the track). And if you take a wander in the Wollongong Botanic Garden, there's a few patches of it in the so-called 'sandstone collection,' quite close to the administration building and the Towri Centre.

This shot shows the sprawling shrubby habit of Swamp Hibiscus, albeit in a non-swamp situation, in Wollongong Botanic Garden. These plants are easy to spot as you wander through the garden. Photo: Tracee Lea (c)

If you live in a near coastal area and have problems with water pooling around your place, this plant could be one to try. It will make the most of the damp conditions and has even been known to survive as a semi-aquatic species (good for those extended La Niña seasons).

It's also a great plant to attract a wide range of insects. Almost as soon as the flowers unfurl, tiny insect pollinators appear. The below close-up of a flower reveals a range of tiny insects present on the petals. 

Tiny insects appearing on the flowers of Swamp Hibiscus (Hibiscus diversifolius). Photo: Emma Rooksby. 

Swamp Hibiscus doesn't just occur in Australia; it's also present in the Philippines, Central and South America, New Guinea, Pacific Islands and Africa. The working theory is that it was originally an African species and has dispersed to other places from there (thanks Wikipedia for referencing the article that advances this theory, and no thanks to publisher Springer, which has not provided an open access link to the article).    

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