| Family | Hydrangeaceae (also placed in Saxifragaceae) |
| Subfamily | Hydrangeoideae |
| Tribe | Hydrangeae |
| Scientific name | Cardiandra amamiohsimensis Koidzumi |
| Synonyms | Cardiandra alternifolia Siebold & Zuccarini var. amamiohsimensis (Koidzumi) Masamune |
| Common name | (Japanese common name) amami-kusa-ajisai (アマミクサアジサイ, 奄美草紫陽花 [meaning: Amami-Ohshima Island herbal Hydrangea]) |
| (English common name) none | |
| Distribution | (Japan) Kyushu (Amami Ohshima Island) |
| (Other nations) none | |
| Habitat | Mountane streamside |
| Chromosomal number | unknown |
| Description | Plants 20-70cm tall. Flowers white petals each 3mm long, flowering in July to September. Perennial plants. |
| Reference | Cardiandra amamiohsimensis Koidz. |
| Cardiandra amamiohsimensis | |
| Phylogeography of the genus Cardiandra based on genetic variation in cpDNA sequences | |
| Note | Endemic to Japan. |
| Cardiandra amamiohsimensis Koidzumi is not a synonym of Cardiandra alternifolia Siebold & Zuccarini subsp. mollendorffii (Hance) H. Hara & H. Ohba. |
| October 2009 at Tsukuba Botanical Garden |
October 2009 at Tsukuba Botanical Garden |
October 2009 at Tsukuba Botanical Garden |