This
attractive shrub is common on the shores of Chek Jawa and Ubin. Sea
hibiscus often forms thickets on the shore and behind the mangroves
above the high water mark. Its presence indicates the boundary between
the end of salt water penetration and the beginning of freshwater
swamp.
The Sea hibiscus is native to Singapore and is now also planted in
our parks. It is related to the more familiar garden-variety red hibiscus.
The Sea hibiscus blooms seasonally.
The green, heart-shaped leaves form an attractive background to the
brightly yellow flowers. The flowers are bright yellow when they first
open in the morning (after sunrise, about 9 am) and turn orangey brown
before falling on the same evening or the following day. The fruits
are small capsules that split to reveal the seeds. The seeds float
and remain alive when immersed in sea water for a long time.
Role in the habitat: The Sea hibiscus
secretes a sweet substance, not in its flowers but its leaves. The
substance is secreted from slits in the veins on the underside near
the stalk. Ants of all sizes can be seen drinking at the leaf!
Cosy Home: Among these, are the
fierce Weaver ants (Oecophylla smaragdina). Weaver ants often
live on this plant, binding the edges of a leaf or two with the silk
produced by their larvae to form a cosy, waterproof and well camouflaged
shelter. These fierce ants probably help to chase off small herbivores
that might try to snack on the Sea hibiscus.
Another creature that is often found on the Sea hibiscus is the Cotton
Stainer Bug (Dysdercus decussatus) that feeds on its seeds.
Human uses: This common seashore
plant is well used by coastal communities. The young leaves can be
eaten and mature leaves fed to cattle. The bark is used to make rope
that has the unique property of being stronger when wet. To make the
rope, bark is stripped lengthwise from the wood and soaked in water
to separate the outer bark from the smooth cream-coloured inner bark.
This is dried and woven into cord which is used to make fishing nets,
hammocks, mats, slings, bow strings, net bags, string for sewing.
The white timber is lightweight (floats well) but tough. Thus in Hawaii,
it is used to make outrigger canoes. Sometimes, young branches were
trained to form the required shapes for this purpose, or bent to shape
in an underground oven. Sea hibiscus has many traditional medicinal
uses. Various parts of the plants are used to cool fevers, soothe
coughs, treat digestive complaints. The slimy sap of the bark, branches
and flower buds were used as a mild laxative or as a lubricant in
childbirth. |
|
Flower
Fruit capsule
Bark
Slits under leaves produces a sweet substance
Weaver ants' nest
made out of
the leaves |
