| Family | Hydrangeaceae |
| Scientific name | Hydrangea hirta (Thunberg) Siebold |
| Synonyms | Viburnum hirtum Thunberg |
| Common name | (Japanese common name) ko-ajisai [small Hydrangea] |
| (English common name) none | |
| Distribution | (Japan) Honshu (west of Kanto region), Shikoku, Kyushu |
| (Other nations) none | |
| Chromosomal number | unknown |
| Description | Plants 1-1.5m. Leaves 5-8cm. Flowers pale blue, flowering in June. Deciduous. Shrub. |
| Reference | Hydrangea hirta (Thunb.) Siebold |
| June 2007 at Mt. Tsukuba | June 2007 at Mt. Tsukuba | June 2007 at Mt. Tsukuba |
| June 2007 at Mt. Tsukuba | June 2007 at Mt. Tsukuba | June 2007 at Mt. Tsukuba |