【Municipal Designation：Natural Monument (Flora)】Miyakojima-so (Hemigraphis okamotoi)

The Miyakojima-so is a perennial plant of the family Acanthaceae. Generally, the Miyakojima-so grows in the sandy areas and on limestone along the shore and below cliffs, with lodged stalks and roots that grow from the nodes, measuring around 10cm in total length. The leaves have fine outgrowths and grow in opposition and are almost circular, around 1-2cm in an oval egg-shape. The terminal spike inflorescence hold two to three flowers with bracts. The flowers are white and consist of four stamens. The fruits are linear and oblong, measuring at around 7-8mm.
In Japan, this plant is found only on Miyako Island, and overseas, they can be found in Taiwan (Lanyu or Orchid Island), the Philippines, Indonesia, New Guinea, and the Polynesian islands. Miyako Island is the northernmost point of distribution of the Miyakojima-so, and the only place in Japan where they grow naturally.
This Polynesian species is phytogeographically significant and is academically important for future studies to understand how its seeds are dispersed and its connection to geologic history.