5) Physocarpus insularis (Nakai) Nakai
P. insularis is a species reported as a new species by Nakai
(1918, 1952), and is currently designated as an endemic
plant and a rare plant. However, Kim et al. (2000) recognized
it as the same one with Spiraea chamaedryfolia growing
inland based on the characteristics of the bark, shape of a
wax gourd, shape of leaf, a stamen of a flower, an ovary,
follicle and distribution of hair of Physocarpus insularis
(Nakai) Nakai. This divides the two plants only based on
the external morphology, and it is judged that it would be
necessary to figure out accurate nature through general tests