The hibiscus hamabo, whose yellow flowers bloom in midsummer,
grows in colonies along the coast from the Izu preninsula down to Amami-Oshima Island.
A member of the hibiscus genus, its beautiful flowers make it a popular garden plant.
The hibiscus hamabo typically inhabits the edges of wetlands slightly flooded with seawater at high tide.
The similarities between plants here and those in mangroves also sees them referred to as semi-mangrove plants.
However, they tend to grow in relatively small river mouths as they are not as well adapted to processing salt as typical mangrove plants like black mangrove and Kandelia obovata are.
This unique environment is on the decrease due to development, with the number of wild plants so scarce in some regions that it has been put on the endangered list.
The hibiscus hamabo extends new branches every year and adorns the tip with 4 flower buds.
These are one-day flowers that blossom sequentially between July and August, opening at dawn and closing at dusk.
After pollinating for this brief period, the ovary positioned at the base of the petal develops and creates seeds.
The 4 flower buds at the tip of each branch blossom within several weeks of each other making it difficult to distinguish flower buds from seeds that have finished flowering without close inspection.
The seeds have developed calyx extending from their base, a measure thought to ward off parasitic moths.
We still don’t know the exact reason for having a gap of several weeks between each flowering, or how they decide the order in which to flower.
Whatever the reason may be for this broad range of flowering times,
mature fruit begins to appear in early September, dropping into the sea to be transported by ocean currents in what is considered to be a technique for expanding the area of distribution.
According to one theory, the calyx of the hibiscus hamabo not only keeps parasites out,
but has a kind of air pressure sensor at its base that releases fruit into the ocean currents should strong typhoon-like winds blow.
Although it may seem like common sense that seeds are blown away by a strong wind,
wouldn’t it be amazing if this was a clever mechanism designed to spread the flowering period out in order to wait for typhoons that approach between September and October.
The genetic makeup of hibiscus hamabo seeds is noticeably different between regions.
There is a tendency towards smaller flowers and briefer flowering intervals the further north one goes.
It makes sense that that typhoon-related seed proliferation is more effective in regions further south.
And if this too is being controlled on a genetic level,
it can be said that this air pressure sensor is a fundamental ability that the hibiscus hamabo has devised for the preservation of its seeds.
Humans do not have such refined sensors with which to measure the natural world.
However, humankind posses the power of analysis, one that goes beyond our natural limitations.
The protection of this diverse and beautiful earth through the analysis of nature is a mission that has been entrusted to humankind.