| Family | Urticaceae |
| Scientific name | Pilea pumila var. hamaoi (Makino) C. J. Chen |
| Synonyms | Pilea hamaoi Makino |
| Common name | (Japanese common name) mizu (ミズ [meaning: water plants]) |
| (English common name) none | |
| Distribution | (Japan) Hokkaido, Honshu, Shikoku, Kyushu |
| (Other nations) Korea, China | |
| Habitat | Swamp |
| Chromosomal number | unknown |
| Description | Plants 20-40cm tall. Leaves 2-5.5cm long. Flowers flowering in September to October. Annual plants. |
| Reference | Pilea pumila var. hamaoi (Makino) C. J. Chen |
| October 2006 at Tsukuba Botanical Garden |
October 2006 at Tsukuba Botanical Garden |
October 2006 at Tsukuba Botanical Garden |